CSET 215 Domain 2: Physical Sciences

Apply knowledge of the principles of conservation of matter to chemical reactions, including balancing chemical equations.

- Conservation of matter: It states that in any given system that is closed to the transfer of matter (in and out), the amount of matter in the system stays constant. A concise way of expressing this law is to say that the amount of matter in a system is conserved. - In any chemical change, one or more initial substances change into a different substance or substances. Both the initial and final substances are composed of atoms because all matter is composed of atoms. According to the law of conservation of matter, matter is neither created nor destroyed, so we must have the same number and type of atoms after the chemical change as were present before the chemical change. - The MASS of the reactants must equal the MASS of the products. - The principles of stoichiometry are based upon the law of conservation of mass. Matter can neither be created nor destroyed, so the mass of every element present in the product(s) of a chemical reaction must be equal to the mass of each and every element present in the reactant(s). - Stoichiometry is a branch of chemistry that deals with the relative quantities of reactants and products that are consumed/produced within a given chemical reaction. In order to make any stoichiometric determinations, however, we must first look to a balanced chemical equation. In a balanced chemical equation, we can easily determine the stoichiometric ratio between the number of moles of reactants and the number of moles of products, because this ratio will always be a positive integer ratio. - In a balanced reaction, both sides of the equation have the same number of elements. The stoichiometric coefficient is the number written in front of atoms, ion and molecules in a chemical reaction to balance the number of each element on both the reactant and product sides of the equation.

Describe the effect of temperature, pressure, and concentration on chemical equilibrium (Le Chatelier's principle) and reaction rate.

- Le Châtelier's principle: When a system at equilibrium is subjected to change (e.g., in temperature, pressure, concentration, or volume) the system changes to a new equilibrium and this change partially counteracts the change applied to the system - An external stress can change the system, and the system reacts in a way that reduced or opposes the change as much as possible CONCENTRATION: A + 2B <----> C + D : the position of the equilibrium moves to the right if you increase the volume of A A + 2B <----> C + D : the position of the equilibrium moves to the left if you decrease the concentration of A PRESSURE: Pressure is caused by gas molecules hitting the sides of their container. The more molecules you have in the container, the higher the pressure will be. The system can reduce the pressure by reacting in such a way as to produce fewer molecules. A + 2B <----> C + D : the position of equilibrium moves to right if you increase the pressure on the reaction + Increased pressure: In this case, there are 3 molecules on the left-hand side of the equation, but only 2 on the right. By forming more C and D, the system causes the pressure to reduce. Increasing the pressure on a gas reaction shifts the position of equilibrium towards the side with fewer molecules. A + 2B <----> C + D : The position of equilibrium moves to the left if you decrease the pressure on the reaction + Decreased pressure: The equilibrium will move in such a way that the pressure increases again. It can do that by producing more molecules. In this case, the position of equilibrium will move towards the left-hand side of the reaction. Decreasing the pressure on a gas reaction shifts the position of equilibrium towards the side with more molecules. TEMPERATURE: If we picture heat as a reactant or a product, we can apply Le Chatelier's principle just like we did in our discussion on raising or lowering concentrations. - ENDOTHERMIC: For instance, if we raise the temperature on an endothermic reaction, it is essentially like adding more reactant to the system, and therefore, by Le Chatelier's principle, the equilibrium will shift the right. Conversely, lowering the temperature on an endothermic reaction will shift the equilibrium to the left, since lowering the temperature in this case is equivalent to removing a reactant. If energy in the form of heat is added to an endothermic reaction, the equilibrium will shift to the right and more product is made. - EXOTHERMIC: For an exothermic reaction, heat is a product. Therefore, increasing the temperature will shift the equilibrium to the left, while decreasing the temperature will shift the equilibrium to the right. If a reaction is exothermic, meaning it gives off heat as it proceeds forward, increasing the temperature of the reaction leads to a shift to the left. Therefore, more product is being broken down and more reactant is being made. As product of a usually exothermic reaction is broken down, energy is absorbed, so by making more of the reactants, some of the energy that is added to the system through the increased temperature is then removed.

Analyze displacement, motion, and forces using models (e.g., vector, graphic representation, equations).

- Scalar: quantities with magnitude + Distance: total distance covered during an object's motion (m) ** Change in distance (Δd) = speed (v) x change in time (Δt) + Speed: the rate at which an object covers a certain distance (m/s) ** Instantaneous speed: the speed at a given time ** Average speed: total distance traveled over the entire time interval - Vector: quantities with magnitude and direction + Displacement: overall change in position of an object ** Displacement (Δx) = velocity (v) x change in time (Δt) + Velocity: an object's speed and direction (m/s in direction) ** Velocity = displacement/time à (v) = (Δx)/(Δt) + Acceleration: occurs when velocity changes; can be changed by altering speed or direction (or both) ** Acceleration (a) = (Δv)/(Δt); or change in velocity/change in time - Positive acceleration: acts in the direction of an object's movement - Negative acceleration: acts in the direction opposite to the object's movement; The object will slow down, eventually stop, eventually travel backwards Equations: (Δx) = (v) x (Δt) (v) = (Δx)/(Δt) (a) = (Δv)/(Δt) Displacement and velocity with constant acceleration: vf = vi + aΔt Δx = ½ (vi + vf)Δt a = (vi + vf)/Δt Δx = vf Δt - ½ aΔt2 · xf = xi + vit + ½ at2 vf2 = vi2 + 2ad d = (t (vi + vf))/2 vector: · Step 1: Find the coordinates of your two displacement vectors · Step 2: Move the second displacement vector so it starts where the first displacement vector ended · Step 3: Draw a new vector that is the addition of the two displacement vectors · Step 4: Find the coordinates of the new displacement vector · Find the resultant vector of the vector A (5, -4) and vector B (-3, -2). o Since you are given the coordinates directly, you can go ahead and add the points together following the formula: o (x1 + x2, y1 + y2) à (5 + -3, -4 + -2) = (2, -6)

Analyze the basic substructure of an atom (i.e., protons, neutrons, and electrons).

- atom: the basic unit of an element that carry out chemical reactions. each element is made up of only one type of atom - two elementary particles: electron and quark + quarks make up protons and neutrons (nucleons) + protons have 2 up quarks and 1 down quark; neutrons have 2 down quarks and 1 up quark - strong nuclear force holds quarks together to form protons and neutrons and counteracts the tendency of the positively-charged protons to repel each other - atoms are made up of 3 components and have precise structure. Change it in any way and the behavior or even the type of atom changes. - Neutral atoms: contain the same number of protons as electrons - The electrons (negative charge, negligible mass) in the outer shell determine an atom's behavior during a chemical reaction/chemical behavior of an atom - The number of protons (positively charged, same mass as neutrons) determines the element; The number of protons in the nucleus is called the atomic number (Z) - The number of protons and neutrons (neutral; same mass as proton) together is the mass number (A) - Atomic mass is based on the average atomic masses of its isotopes and the abundance of each isotope; Number of neutrons = atomic mass - atomic number - Adding more electrons produces more orbitals. The orbitals have different shapes. Orbital: the orbit that electrons can take around the nucleus - Valence shell: the electrons in the outer shell that take part in a chemical reaction + Electrons with full valence shells are chemically stable; they don't undergo chemical reactions. An atom without a full valence shell will undergo a chemical reaction in order to obtain a full valence shell + During the reaction, electrons may be gained or lost, or shared between atoms depending on the number of electrons in the valence shell + Octet rule: atoms like to have full valence shells of 8 electrons - Electron configuration: the arrangement of electrons around the atom + S orbitals: one orbital; smallest and can only hold 2 electrons + P orbitals: groups of three orbitals that can have 6 electrons total + D orbitals: groups of five orbitals that can hold 10 electrons total + F orbitals: groups of seven orbitals that can hold 14 electrons total + Order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, (8s, 5g, 6f, 7d, 8p, and 9s) Example: electron configuration of Sm: [Xe] 4f6 6s2

Interpret simple series and parallel circuits.

- circuit: a path that electrons can flow through - series circuit: provides only one path for the electrons to get through the resistive part of the circuit + the total resistance of a series circuit is equal to the sum of all the individual resistances; adding a resistor will always cause the total resistance to increase. ADD RESISTANCES to find equivalent resistance + the current through each resistance and through every part of the circuit if the same. There is only one path for current to flow in a series circuit, so all resistors must have the same current flowing through them. SAME CURRENT at EACH RESISTOR + the voltage lost in each resistance can be different, but the sum of the voltages will always equal the voltage of the battery - parallel circuit: provides multiple paths for electrons to get through the resistive part of the circuit; connect devices along branched pathways. In a simple parallel circuit, each branch is connected to the same two points where a battery is also connected. The battery supplies voltage, which, like a heart, 'pumps' current through the circuit. These multiple pathways allow the total current to divide among the branches, but it also means that the voltage across each branch is the same + each time a new path is added to a parallel circuit, the total resistance will decrease no matter how high the resistance is of the new path. 1/R(eq) = 1/R(1) + 1/R(2) + 1/R(3) --> then at the end the fraction is flipped to get R(eq) + if the total resistance decrease, then the total current leaving and returning to the battery will increase. + the current through each path can be different, but the SUM of all the currents will equal the TOTAL current. The current is being split in multiple ways, so RESISTORS in parallel DO NOT HAVE SAME CURRENT through them. ** Can find the total current and also the current in each resistor. To find the current in each resistor, you can use Ohm's law --> remember the voltage across each resistor is equal to the voltage across the battery because it's a parallel circuit. The sum of these will equal the total current. + the voltage across each resistance will always be equal to the battery voltage * Kirchoff's rules: - the sum of the currents entering a junction must equal the sum of the currents leaving the junction. Conservation of charge: the current may split and go in different directions at the junction, but if you added the total amount of current in each branch, they would equal the amount of current that originally came into that junction - the sum of the voltage differences across all elements of a closed loop must be zero. This rule is based on the law of conservation of energy, and reminds us that as current encounters a resistor there's a 'voltage drop' and that the sum of all voltage drops is equal to the total supplied voltage.

Demonstrate knowledge of the characteristics of the different states of matter.

- matter: anything that has mass and takes up space - gas: a form of matter that does not have a definite volume or shape; has a low density and can diffuse easily - liquid: has a definite volume but not a definite shape. Molecules are more tightly packed but can still move and flow past each other. Able to diffuse and ix with other liquids, but slower mixing than gases. Surface tension: the force of attraction that keeps molecules on the surface of a liquid together. - solid: definite volume and shape. Tightly packed molecules that have limited movement and are incompressible and hold their volume and shape. Typically the densest state of matter (not in water); diffuse slowly and not well - plasma: a gas that has gotten so hot that negatively charged free electrons and positively charged ions exist together in it; these free electrons mean that plasma easily conducts energy. Neither a definite volume nor shape.

Differentiate between atoms and their isotopes, ions, molecules, elements, and compounds.

- matter: anything with mass and that takes up space - substance: a pure form of matter (i.e. water) - mixture: contains more than one type of substance (i.e. steel, air) - elements: a substance compose of ONE type of atom - molecule: a group of 2 or more atoms/elements chemically bonded together - compound: a group of two or more different atoms/elements chemically bonded together--> all compounds are molecules but not all molecules are compounds - ions: an atom that has gained or lost one or more electrons and therefore has a negative or positive charge + Cation: an atom that has lost a valence electron and therefore has more positive protons than negative electrons, so it is positively charged + anion: an atom that has gained valence electron(s) and is negatively charged + Predicting the charge of an ion: *remember octet rule --> they want 8 valence electrons to have a full valence shell - Group IA has one valence electron, so it loses it and becomes +1 charged. - Groups IIA and IIIA lose two and three electrons, respectively, to become charged +2 and +3. - Group IVA can go either way, either losing or gaining four electrons. It rarely forms ions, though. - Group VA, with its five valence electrons, is when things change. - Group VA will gain three electrons to become negatively charged: -3. - Group VIA becomes -2 charged ions. - Group VIIA has seven electrons in its outer shell, so it gains one electron to become -1 charged. - Group VIIIA is the lucky group. This is the noble gas group with full valence electron shells, and they are happy just the way they are - Polyatomic ions you will commonly come across include the sulfate ion (SO42-), the hydrogen carbonate (bicarbonate) ion (HCO3-), the carbonate ion (CO32-), the hydroxide ion (OH-), the nitrate ion (NO3-), and the ammonium ion (NH4+) - isotopes: atoms with the same number of protons but that have a different number of neutrons (same atomic number but different mass numbers) + stable isotopes: have a stable combination of protons and neutrons so they don't undergo decay + radioactive isotopes: have an unstable combination of protons and neutrons so they have unstable nuclei; undergo decay (can emit alpha, beta, and gamma rays)

Demonstrate knowledge of the physical and chemical characteristics, including pH, of acids, bases, and neutral solutions.

- pH scale: pH= -log [h+]; logarithmic scale (from one pH unit to the next, the concentration of H+ changes by 10x); used to represent the level of acidity in a solution + pH below 7 is an acid + pH above 7 is basic + pH of 7 is neutral; water can break down to form H+ and OH- ions, when these ions are equal to each other, the value is 1 x 10-7 - the pH scale is based on the concentration of H+ ions in a solution (H+ ions actually exist as H3O+ in solution) - pH actually means the hydrogen (H) potential (p) of the solution - water exists in an equilibrium with the hydronium ion (H3O+) and the hydroxide ion (OH-) - when acids are added, they release more hydrogen ions into the solution --> more hydrogen ions = a lower pH and more acidic solution ACIDS: - Weak acids: partially release the hydrogen atoms that are attached; may lower pH by dissociation of hydrogen ions but not completely; Ex: acetic acid (vinegar), citric acid (citrus fruits) - Strong acids: completely dissociate and release ALL of their hydrogen atoms--> more potent in lowering the pH of a solution; Ex: (there are 7 strong acids): hydrochloric acid (stomach acid) and sulfuric acid (corrosive acid in batteries and fertilizers) - Turns blue litmus paper RED - Taste SOUR in aqueous solutions - some acids are corrosive - Form SALTS through reactions with some metals and bases - The body require acids to maintain them: + Hydrochloric acid: produced in stomach to assist in digestion + Fatty acids: released when the body breaks down fats for energy + ATP acts like an acid because when added to a solution, ATP releases hydrogen ions + Nucleic acids: responsible for genetic makeup + Amino acids also release a small amount of hydrogen ions into aqueous solutions BASES: describe solutions greater than 7 - Potential for accepting rather than released hydrogen ions, and can neutralize acids - Taste BITTER - Feel SLIPPERY - red litmus paper turns blue under basic or alkaline conditions - Strong bases react corrosively with other materials and can burn your skin - Base that doesn't fully dissociate: weak base - Base that fully dissociates into ions: strong bases (NaOH) - Uses: + Used as cleaning agents and antacid medications + Soaps, lye (oven cleaner), milk of magnesia, Tums - Carbon dioxide in atmosphere puts pressure on ocean's ability to neutralize acid: + As carbon dioxide dissolves into the ocean, it reacts with water to form carbonic acid + This drives hydrogen ion to dissociate, forming bicarbonate, which can further dissociate a hydrogen ion to form carbonate + Calcium carbonate by marine organisms (base) **Neutral litmus paper is purple

Apply knowledge of physical changes of matter and physical properties of matter.

- physical changes of matter: phase change: a transition of matter from one state to another + freezing: liquid to solid + melting: solid to liquid + sublimation: solid to gas + deposition: gas to solid + condensation: gas to liquid + vaporization: liquid to gas + ionization: gas to plasma + recombination: plasma to gas - endothermic: energy must be added to the system. I.e. turning a solid to liquid (melting) or liquid to gas (vaporization) - exothermic: energy is released from the system as the substance changes state. I.e. turning a gas to liquid (condensation) or liquid to solid (freezing) - Physical property: a characteristic that can be observed and measured without changing the composition of the same; can be used to describe mixtures and pure substances --> Pure substances have uniform and unchanging compositions, they also have consistent and unchanging physical properties + Extensive physical properties: those that are dependent on the amount of substance present * Volume: the amount of three-dimensional space occupied by a material + Intensive physical properties: those that do not depend on the amount of the substance present * Density: determined by dividing the mass of a given amount of a substance by its volume (g/mL); Will be the same no matter how much of it you have * Odor: used to identify chemicals and materials such as spices * Hardness: measurable and often recorded using the Moh's hardness scale * Color o Appearance, texture, color, odor, Melting point, Boiling point, density, solubility, polarity

Demonstrate knowledge of the central role of carbon in the chemistry of living systems.

- proteins, nucleic acids, carbohydrates, and lipids (all macromolecules) contain carbon; all living things contain carbon in some form - carbon is an integral part of many biological processes, including reproduction, photosynthesis, and respiration - carbon's molecular structure allows it to bond in many different ways with many different elements. + Individual carbon atoms have an incomplete outermost electron shell. With an atomic number of 6 (six electrons and six protons), the first two electrons fill the inner shell, leaving four in the second shell. Therefore, carbon atoms can form four covalent bonds with other atoms to satisfy the octet rule. + The methane molecule provides an example: it has the chemical formula CH4. Each of its four hydrogen atoms forms a single covalent bond with the carbon atom by sharing a pair of electrons. This results in a filled outermost shell. - carbon cycle shows how it moves through living and non-living aspects of the environment - hydrocarbons: molecules that contain only carbon and hydrogen and that can form chains and rings due to the bonding patterns of carbon atoms + hydrocarbons can have single, double, or triple bonds between carbon atoms (affects the geometry/3D shape of the molecules which affects the function) + the covalent bonds between the atoms in hydrocarbons store high amounts of energy, which can be released when these molecules are burned (oxidized) + hydrocarbon benzene rings (rings of hydrocarbons with double bonds) are present in many biological molecules including some amino acids and most steroids (lipids), which includes cholesterol and estrogen and testosterone hormones + in triglycerides (fats and oils), long carbon chains known as fatty acids may contain double bonds that can be in either cis (liquid at room temperature) or trans (solid at room temperature) configuration - carbohydrates: sugars, starches + carbon, hydrogen, oxygen + provides energy to cells, stores energy, forms body structures + monomer: monosaccharide - lipids: fats, oils, steroids + carbon, hydrogen, oxygen + stores energy, forms cell membranes, carries messages - proteins: enzymes, antibodies + carbon, hydrogen, oxygen, nitrogen, sulfur + helps cells keep their shape, makes up muscles, speeds up chemical reactions, carries messages and materials + monomer: amino acid - nucleic acids: DNA, RNA + carbon, hydrogen, oxygen, nitrogen, phosphorus + contains instructions for proteins, passes instructions from parents to offspring, helps make proteins + monomer: nucleotide

Apply knowledge of electromagnetic radiation, including analyzing evidence that supports the wave and particle models that explain the properties of electromagnetic radiation.

EM radiation: defined as the movement of energy through space or a medium, comprising both an electric and magnetic wave that oscillate at right angles to each other and to the direction of wave travel. Each EM wave has both frequency and wavelength, the latter being defined as the distance between positive or negative wave peaks in either the electric or magnetic waves. Wavelength is easily calculated as the speed of light divided by the frequency, like in this equation provided here: 𝜆 = c/f where 𝜆 is the wavelength in meters, c is the speed of light 3 x 10^8 m/s, f is the frequency in hertz (1/s) - example: a particular wave if electromagnetic radiation has a frequency of 1.5 x 10^14 Hz. What is the wavelength of the wave? 𝜆 = c/f so 𝜆 = (3 x 10^8 m/s)/(1.5 x 10^14 Hz) = 2.00 x 10^-6 m All electromagnetic radiation travels through a vacuum at the same speed, called the speed of light. Its speed in any given medium depends on its wavelength and the properties of that medium. Electromagnetic waves can be classified and arranged according to their various wavelengths/frequencies; this classification is known as the electromagnetic spectrum - Highest frequency/lowest wavelength to lowest frequency/highest wavelength: gamma rays, x-rays, UV, visible light (shortest wavelength to highest wavelength: blue, green, yellow, red), infrared radiation, microwave, radio waves - To the right of the visible spectrum, we find the types of energy that are lower in frequency (and thus longer in wavelength) than visible light. These types of energy include infrared (IR) rays (heat waves given off by thermal bodies), microwaves, and radio waves. These types of radiation surround us constantly, and are not harmful, because their frequencies are so low. lower frequency waves are lower in energy, and thus are not dangerous to our health. - To the left of the visible spectrum, we have ultraviolet (UV) rays, X-rays, and gamma rays. These types of radiation are harmful to living organisms, due to their extremely high frequencies (and thus, high energies). Photon: - Through careful observations of the photoelectric effect (the photoelectric effect, wherein electrons are emitted from atoms when they absorb energy from light), Albert Einstein realized that there were several characteristics that could be explained only if EM radiation is itself quantized. It means that the apparently continuous stream of energy in an EM wave is actually not a continuous stream at all. In fact, the EM wave itself is actually composed of tiny quantum packets of energy called photons. - A photon is the elementary particle, or quantum, of light. Photons can be absorbed or emitted by atoms and molecules. When a photon is absorbed, its energy is transferred to that atom or molecule. Because energy is quantized, the photon's entire energy is transferred (remember that we cannot transfer fractions of quanta, which are the smallest possible individual "energy packets"). The reverse of this process is also true. When an atom or molecule loses energy, it emits a photon that carries an energy exactly equal to the loss in energy of the atom or molecule. This change in energy is directly proportional to the frequency of photon emitted or absorbed. This relationship is given by Planck's famous equation: E = hv where E is the energy of the photon absorbed or emitted (Joules), v is the frequency of the photon (hertz), and h is planck's constant (6.626 x 10^-34 Js) - example: the wavelength of orange light is 590 - 635 nm, and the wavelength of green light is about 520-569 nm. Which color of light is more energetic? green light is more energetic because it has a shorter wavelength, and thus a higher frequency and a higher energy, than orange light. -Under specific circumstances, light acts as a wave and under others as a particle + Electromagnetic radiation, commonly called light, is the transfer of energy by waves called electromagnetic waves. These waves consist of vibrating electric and magnetic fields. Where does electromagnetic energy come from? It is released when electrons return to lower energy levels in atoms. Electromagnetic radiation behaves like continuous waves of energy most of the time. Sometimes, however, electromagnetic radiation seems to behave like discrete, or separate, particles rather than waves. So does electromagnetic radiation consist of waves or particles? + Albert Einstein developed a new theory about electromagnetic radiation. The theory is often called the wave-particle theory. It explains how electromagnetic radiation can behave as both a wave and a particle. Einstein argued that when an electron returns to a lower energy level and gives off electromagnetic energy, the energy is released as a discrete "packet" of energy. We now call such a packet of energy a photon. According to Einstein, a photon resembles a particle but moves like a wave. You can see this in the Figure below. The theory posits that waves of photons traveling through space or matter make up electromagnetic radiation. + an electron returns to a lower energy level and releases a discrete photon of energy. That photon travels outwards as a wave + A wave model of light is useful for explaining brightness, color, and the frequency-dependent bending of light at a surface between media (prisms). - Energy of a Photon + A photon isn't a fixed amount of energy. Instead, the amount of energy in a photon depends on the frequency of the electromagnetic wave. The frequency of a wave is the number of waves that pass a fixed point in a given amount of time, such as the number of waves per second. In waves with higher frequencies, photons have more energy. - Evidence for the Wave-Particle Theory + After Einstein proposed his theory, evidence was discovered to support it. For example, scientists shone laser light through two slits in a barrier made of a material that blocked light. You can see the setup of this type of experiment in the Figure below. Using a special camera that was very sensitive to light, they took photos of the light that passed through the slits. The photos revealed tiny pinpoints of light passing through the double slits. This seemed to show that light consists of particles. However, if the camera was exposed to the light for a long time, the pinpoints accumulated in bands that resembled interfering waves. Therefore, the experiment showed that light seems to consist of particles that act like waves. double-slit experiment: In the basic version of this experiment, a coherent light source, such as a laser beam, illuminates a plate pierced by two parallel slits, and the light passing through the slits is observed on a screen behind the plate. The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen - a result that would not be expected if light consisted of classical particles. However, the light is always found to be absorbed at the screen at discrete points, as individual particles (not waves); the interference pattern appears via the varying density of these particle hits on the screen. Furthermore, versions of the experiment that include detectors at the slits find that each detected photon passes through one slit (as would a classical particle), and not through both slits (as would a wave). However, such experiments demonstrate that particles do not form the interference pattern if one detects which slit they pass through. These results demonstrate the principle of wave-particle duality. - The wave-like nature of light explains most of its properties: reflection/refraction diffraction/interference Doppler effect - the photoelectric effect explains EM radiation as a particle + Photoelectric effect: if a certain metal plate is irradiated with light, an electron is ejected which can be detected when it interacts with a positively charged wire or plate sensor. + The photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material. Electrons emitted in this manner are called photoelectrons.

Demonstrate knowledge of the relationship between wave frequency, wavelength, and amplitude and energy.

Frequency (f): number of waves passing a specific point per second F = 1/T - Unit: Hz or (s^-1) --> one cycle (one wave) per second Wavelength (𝜆 ): the distance between adjacent identical parts of a wave, parallel to the direction of propagation --> unit: meters or nm + The distance between two wave crests or two wave troughs, expressed in various metric measures of distance + EM wave: 𝜆 = c/f, where 𝜆 is the wavelength in meters, c is the speed of light 2 x 10^8 m/s, and f is frequency in hertz or 1/s Amplitude: distance between the resting position (null point) and the maximum displacement of the wave Energy: related to its amplitude and frequency --> in Joules - EM wave: + Energy of an EM photon: E = hv where h is Planck's constant and v is the frequency of the light absorbed or emitted + Photon: the elementary particle, or quantum, of light that can be absorbed or emitted by atoms and molecules + Shorter wavelength = higher frequency = higher energy - Mechanical wave: + In a mechanical wave, the energy, frequency, and amplitude are related. + The greater the energy in the wave, the greater the movement of the particles from their resting position and so the greater the amplitude. + The higher the frequency, the faster the particles oscillate and so the greater the amount of energy in the particles + Wave amplitude of a longitudinal wave is the distance between particles of the medium where it is compressed by the wave. Wave amplitude is determined by the energy of the disturbance that causes the wave. A wave caused by a disturbance with more energy has greater amplitude. amplitude: how far the molecules of the medium have moved from their normal rest position Period: the time it takes for one wave cycle to complete, number of seconds per wave T =1/ f --> unit: seconds Wave velocity (𝑣𝑤): the speed at which the disturbance moves 𝑣𝑤 = 𝜆/T or 𝑣𝑤 = f 𝜆

Identify fundamental forces, including gravity, nuclear forces, and electromagnetic forces (magnetic and electric), and recognize their roles in nature, such as the role of gravity in maintaining the structure of the universe.

GRAVITY: attraction between 2 objects that have mass - Causes ocean tides - Gravity holds planets, stars, solar systems, and galaxies together - infinite range - weakest WEAK NUCLEAR FORCE: responsible for particle decay (change of one type of subatomic particle into another) and thus radioactivity - Critical for nuclear fusion reactions that power the sun and produce the energy needed for most life forms - Allows us to date fossils/rocks - Beta decay (neutron into proton and ejects an electron or a proton turns into a neutron and ejects a positron) --> only the action of the weak force changing protons into neutrons within a star like the sun allows nuclear fusion to get off the ground within its core at all. The burning of stars - and so the existence of life - depends on the weak force. - short range: within the diameter of a nucleus - 2nd weakest ELECTROMAGNETIC: acts between charged particles - Opposite charges attract one another, wile like charges repel - The greater the charge, the greater the force - Consists of the electric and magnetic force - Responsible for some of the most commonly experienced phenomena: friction, elasticity, the normal force, the force holding solids together in a given shape - Responsible for drag on flying objects - These actions can occur because of charged particles interacting with one another - atoms: electrons are kept in the orbit around the nucleus by the electromagnetic force, because the nucleus in the center of the atom is positively charged and attracts the negatively charged electrons. - light - chemical bonding - infinite range - 2nd strongest STRONG NUCLEAR FORCE: binds the fundamental particles of matter together to form larger particles. It holds together the quarks that make up protons and neutrons, and part of the strong force also keeps the protons and neutrons of an atom's nucleus together; gluons - Positively charged protons held together --> strong force overcomes the electromagnetic force which tries to repel like charges in the nucleus of an atom - short range: within 0.1% of a proton's diameter - strongest

Demonstrate knowledge of the principle of conservation of energy, including analyzing energy transfers.

- Law of conservation of energy (1st law of thermodynamics): energy cannot be created or destroyed but it can be changed from one form to another and transferred from one system to another W = E(initial) - E(final) - Mechanical energy (Ep + Ek) of a system is constant --> any change in Ep is equal and opposite to any change in Ek --> Etotal = Ep + Ek --> KEi+PEi=KEf+PEf - When work is done, the energy of the system changes. If work is done on the system, energy is added. If the system does work on the environment, energy goes out of the system - In systems, energy is not perfectly conserved. Energy is always being lost to the environment, often due to frictional components - example: consider a golfer on the moon - gravitational acceleration 1.625 m/s2 - striking a golf ball. the ball leaves the club at an angle of 45 degrees to the lunar surface traveling at 20 m/s both horizontally and vertically - total velocity 28.28 m/s. How high would the golf ball go? + E (mechanical) = 1/2mv^2 + mgh + apply conservation of energy: 1/2 mv^2 (initial) = mgh + 1/2mv^2 (final) + solve for h: h = (1/2 (vi^2 - vf^2))/g = (1/2 (28.28^2 -20^2)/1.625 = 123 m + how did we know the final speed was 20 m/s? at the peak height, the vertical component of the velocity becomes zero, so the only velocity component at peak height is the horizontal component which doesn't change during the flight and is 20 m/s. - even though energy is conserved in an energy conversion process, the output of useful energy or work will be less than the energy input. the efficiency of an energy conversion process is: efficiency = useful energy or work output/ total energy input = W(out)/E(in)

Analyze how chemical energy in fuel is transformed to heat.

- A fuel is a material that can be burned to produce heat, light or power. - Examples of fuel include wood, coal, natural gas, and oil. The energy stored within them originally came from the sun. It was absorbed by plants, and stored inside them. In the case of wood that's the end of the story: trees that were chopped down contain this energy. But some of the energy did not go into logs of wood. All plants that lived in the past either died or were eaten by animals, and those animals eventually died too. This dead plant and animal material was compressed on the high heat and pressure over millions of years to form things like coal, oil, and gas. The original energy from the sun is stored in these fuels. - When we burn fuels, it begins a process called combustion. Combustion is where you burn a fuel in the presence of an oxidant like oxygen. Heat is produced, because the bonds in the fuel store more energy than the bonds in the water and carbon dioxide that are the products of combustion. - Energy is the capacity for doing work or supplying heat. When you fill your car with gasoline, you are providing it with potential energy. Chemical potential energy is the energy stored in the chemical bonds of a substance. The various chemicals that make up gasoline contain a large amount of chemical potential energy that is released when the gasoline is burned in a controlled way in the engine of the car. + The release of that energy does two things. Some of the potential energy is transformed into work, which is used to move the car. At the same time, some of the potential energy is converted to heat, making the car's engine very hot. The energy changes of a system occur as either heat or work, or some combination of both. - Due to the absorption of energy when chemical bonds are broken, and the release of energy when chemical bonds are formed, chemical reactions almost always involve a change in energy between products and reactants. By the Law of Conservation of Energy, however, we know that the total energy of a system must remain unchanged, and that oftentimes a chemical reaction will absorb or release energy in the form of heat, light, or both. The energy change in a chemical reaction is due to the difference in the amounts of stored chemical energy between the products and the reactants. This stored chemical energy, or heat content, of the system is known as its enthalpy. - Exothermic reactions release heat and light into their surroundings. For example, combustion reactions are usually exothermic. In exothermic reactions, the products have less enthalpy (stored chemical energy/heat content) than the reactants, and as a result, an exothermic reaction is said to have a negative enthalpy of reaction. This means that the energy required to break the bonds in the reactants is less than the energy released when new bonds form in the products. Excess energy from the reaction is released as heat and light. - Another useful term is the heat of combustion, which is the energy mostly of the weak double bonds of molecular oxygen[1] released due to a combustion reaction and often applied in the study of fuels. Food is similar to hydrocarbon and carbohydrate fuels, and when it is oxidized to carbon dioxide and water, the energy released is analogous to the heat of combustion (though not assessed in the same way as a hydrocarbon fuel — see food energy). - Chemical potential energy is a form of potential energy related to the structural arrangement of atoms or molecules. This arrangement may be the result of chemical bonds within a molecule or otherwise. Chemical energy of a chemical substance can be transformed to other forms of energy by a chemical reaction. As an example, when a fuel is burned the chemical energy of molecular oxygen is converted to heat, and the same is the case with digestion of food metabolized in a biological organism. Green plants transform solar energy to chemical energy (mostly of oxygen) through the process known as photosynthesis, and electrical energy can be converted to chemical energy and vice versa through electrochemical reactions. - Atoms bond together to form compounds because in doing so they attain lower energies than they possess as individual atoms. A quantity of energy, equal to the difference between the energies of the bonded atoms and the energies of the separated atoms, is released, usually as heat. That is, the bonded atoms have a lower energy than the individual atoms do. When atoms combine to make a compound, energy is always given off, and the compound has a lower overall energy. - During chemical reactions, the bonds between atoms may break, reform or both to either absorb or release energy. The result is a change to the potential energy of the system. The heat absorbed or released from a system under constant pressure is known as enthalpy, and the change in enthalpy that results from a chemical reaction is the enthalpy of reaction. - As a rule, breaking bonds between atoms requires adding energy. The stronger the bond, the more energy it takes to break the bond. To make the product propane, a new C-C and two new C-H bonds are then formed. Since breaking bonds requires adding energy, the opposite process of forming new bonds always releases energy. The stronger the bond formed, the more energy is released during the bond formation process. In this particular reaction, because the newly formed bonds release more energy than was needed to break the original bonds, the resulting system has a lower potential energy than the reactants. This means the enthalpy of reaction is negative. ·-In an exothermic reaction, the released energy doesn't simply disappear. Instead it is converted to kinetic energy, which produces heat. This is observed as an increase in temperature as the reaction progresses. Exothermic reactions: Heat is released. 1) Combustion: The burning of carbon-containing compounds uses oxygen, from air, and produces carbon dioxide, water, and lots of heat. For example, combustion of methane CH4 can be represented as follows: CH4 + 2(O2) ---> CO2 + 2H2O + heat 2) Rain: Condensation of water vapor into rain releasing energy in the form of heat is an example of an exothermic process. what is the enthalpy of a reaction: enthalpy of a reaction is defined as the heat energy change (ΔH) that takes place when reactant go to products. If heat is absorbed during the reaction, ΔH is positive; if heat is released, then ΔH is negative ΔH = ΔH(bonds broken in reactants) - ΔH(bonds made in products)

Demonstrate knowledge of how lenses are used in simple optical systems, including the camera, telescope, microscope, and eye.

- A lens is an instrument that refracts (or bends) light in such a way as to allow the user to see the world around them in a different way. A lens is a piece of glass (or plastic or other material) that has been carefully shaped so that the way it refracts light forms an image. - A simple lens is a basic device that uses a single lens to refract light. The most obvious example of a simple lens is a magnifying glass, which uses a single lens to magnify an object - A compound lens uses multiple lenses. An example of a compound lens is a compound microscope, which uses multiple lenses to increase the viewer's capacity to magnify an object. - Concave lenses are thinnest in the middle and widest at the edges, as if the face of the lens were 'caving' in on itself. This shape results in spreading the light into a wider arc. + From the diagram, it's clear that the lens causes rays of light to diverge, or spread apart, as they pass through it. Note that the image formed by a concave lens is on the same side of the lens as the object. It is also smaller than the object and right-side up. However, it isn't a real image. It is a virtual image. Your brain "tricks" you into seeing an image there. The light rays actually pass through the glass to the other side and spread out in all directions. - Convex lenses, on the other hand, are thickest in the middle and thinnest at the edges, thus focusing light on a central point. Most lenses that we commonly think of (like in microscopes, cameras, the human eye, and telescopes, a magnifying glass) are convex. + A convex lens causes rays of light to converge, or meet, at a point called the focus (F). A convex lens forms either a real or virtual image. It depends on how close the object is to the lens relative to the focus. * if the object is closer to the lens than the focus is, a virtual image forms on the same side of the lens as the object. The image is right-side up and enlarged * if the object is farther from the lens that the focus is, a real image forms on the side of the lens opposite the object and the image is upside down. the image may be smaller, larger, or the same size as the object, depending on the object's distance from the lens. the farther the object is, the more reduced the image is + A magnifying glass is a convex lens that lets the observer see a larger image of the object under observation. Microscope: - The objective lenses offer an additional 4x, 10x, 40x, or 100x magnification, on top of the 10x of the ocular lenses. - A compound microscope uses multiple lenses to magnify an image for an observer. It is made of two convex lenses: the first, the ocular lens, is close to the eye; the second is the objective lens. - two convex lenses. The first lens is called the objective lens and is closest to the object being observed. The distance between the object and the objective lens is slightly longer than the focal length, f0. The objective lens creates an enlarged image of the object, which then acts as the object for the second lens. The second or ocular lens is the eyepiece. The distance between the objective lens and the ocular lens is slightly shorter than the focal length of the ocular lens, fe. This causes the ocular lens to act as a magnifying glass to the first image and makes it even larger. Because the final image is inverted, it is farther away from the observer's eye and thus much easier to view. Camera: Cameras work very similarly to how the human eye works. The iris is similar to the lens; the pupil is similar to the aperture; and the eyelid is similar to the shutter. - The camera lens allows the light to enter into the camera and is typically convex. The two major features of a lens are focal length and aperture. The focal length determines the magnification of the image, and the aperture controls the light intensity. - The aperture controls the intensity of the light entering the camera, and the shutter controls the exposure — the amount of time that the light is allowed into the camera. Telescope: - Figure 1a shows a telescope made of two lenses, the convex objective and the concave eyepiece, the same construction used by Galileo. Such an arrangement produces an upright image and is used in spyglasses and opera glasses. - The most common two-lens telescope, like the simple microscope, uses two convex lenses and is shown in Figure 1b + Refracting Telescopes: uses a convex lens to collect and focus light. it uses another convex lens in the eyepiece to enlarge the image made by the first convex lens. The objective lens (at point 1) and the eyepiece (point 2) gather more light than a human eye can collect by itself. The image is focused at point 5, and the observer is shown a brighter, magnified virtual image at point 6. The objective lens refracts, or bends, light. This causes the parallel rays to converge at a focal point, and those that are not parallel converge on a focal plane. + Reflecting Telescopes: uses a concave mirror to collect and focus light. the light then strikes a small plane mirror, which reflects the light into the eyepiece at the side of the microscope. a convex lens in the eyepiece enlarges the image. these telescopes use either one or a combination of curved mirrors that reflect light to form an image. They allow an observer to view objects that have very large diameters and are the primary type of telescope used in astronomy. The object being observed is reflected by a curved primary mirror onto the focal plane. (The distance from the mirror to the focal plane is called the focal length. ) A sensor could be located here to record the image, or a secondary mirror could be added to redirect the light to an eyepiece. Eye: - The cornea and lens of an eye act together to form a real image on the light-sensing retina, which has its densest concentration of receptors in the fovea and a blind spot over the optic nerve. The power of the lens of an eye is adjustable to provide an image on the retina for varying object distances. Layers of tissues with varying indices of refraction in the lens. - eye parts: cornea: the transparent part of the eye that covers the front portion of the eye. It covers the pupil (the opening at the center of the eye), iris (the colored part of the eye), and anterior chamber (the fluid-filled inside of the eye). The cornea's main function is to refract, or bend, light. retina: a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed. - The cornea and lens form a system that, to a good approximation, acts as a single thin lens. For clear vision, a real image must be projected onto the light-sensitive retina, which lies at a fixed distance from the lens. The lens of the eye adjusts its power to produce an image on the retina for objects at different distances. The center of the image falls on the fovea, which has the greatest density of light receptors and the greatest acuity (sharpness) in the visual field. The variable opening (or pupil) of the eye along with chemical adaptation allows the eye to detect light intensities from the lowest observable to 10^10 times greater (without damage). This is an incredible range of detection. Our eyes perform a vast number of functions, such as sense direction, movement, sophisticated colors, and distance. Processing of visual nerve impulses begins with interconnections in the retina and continues in the brain. The optic nerve conveys signals received by the eye to the brain. - The retina is the paper-thin tissue that lines the back of the eye and contains the photoreceptor (light sensing) cells (rods and cones) that send visual signals to the brain. The pit or depression within the macula, called the fovea, provides the greatest visual acuity (sharpness) - Refractive indices are crucial to image formation using lenses. The biggest change in the refractive index, and bending of rays, occurs at the cornea rather than the lens. The ray diagram in Figure 2 shows image formation by the cornea and lens of the eye. The rays bend according to the refractive indices provided in Table 1. The cornea provides about two-thirds of the power of the eye, owing to the fact that speed of light changes considerably while traveling from air into cornea. The lens provides the remaining power needed to produce an image on the retina. The cornea and lens can be treated as a single thin lens, even though the light rays pass through several layers of material (such as cornea, aqueous humor, several layers in the lens, and vitreous humor), changing direction at each interface. The image formed is much like the one produced by a single convex lens. Images formed in the eye are inverted but the brain inverts them once more to make them seem upright. - An image is formed on the retina with light rays converging most at the cornea and upon entering and exiting the lens. Rays from the top and bottom of the object are traced and produce an inverted real image on the retina. The distance to the object is drawn smaller than scale. - As noted, the image must fall precisely on the retina to produce clear vision—that is, the image distance di must equal the lens-to-retina distance. Because the lens-to-retina distance does not change, the image distance di must be the same for objects at all distances. The eye manages this by varying the power (and focal length) of the lens to accommodate for objects at various distances. The process of adjusting the eye's focal length is called accommodation. A person with normal (ideal) vision can see objects clearly at distances ranging from 25 cm to essentially infinity. However, although the near point (the shortest distance at which a sharp focus can be obtained) increases with age (becoming meters for some older people), we will consider it to be 25 cm in our treatment here. - the accommodation of the eye for distant and near vision. Since light rays from a nearby object can diverge and still enter the eye, the lens must be more converging (more powerful) for close vision than for distant vision. To be more converging, the lens is made thicker by the action of the ciliary muscle surrounding it. The eye is most relaxed when viewing distant objects, one reason that microscopes and telescopes are designed to produce distant images. Vision of very distant objects is called totally relaxed, while close vision is termed accommodated, with the closest vision being fully accommodated. - Relaxed and accommodated vision for distant and close objects. (a) Light rays from the same point on a distant object must be nearly parallel while entering the eye and more easily converge to produce an image on the retina. (b) Light rays from a nearby object can diverge more and still enter the eye. A more powerful lens is needed to converge them on the retina than if they were parallel. - (a) Correction of nearsightedness requires a diverging lens that compensates for the overconvergence by the eye. The diverging lens produces an image closer to the eye than the object so that the nearsighted person can see it clearly. (b) Correction of farsightedness uses a converging lens that compensates for the underconvergence by the eye. The converging lens produces an image farther from the eye than the object so that the farsighted person can see it clearly. In both (a) and (b), the rays that meet at the retina represent corrected vision, and the other rays represent blurred vision without corrective lenses.

Apply knowledge of heat transfer by conduction, convection, and radiation, including analyzing examples of each mode of heat transfer.

- CONDUCTION: Conduction is heat transfer through stationary matter by physical contact. (The matter is stationary on a macroscopic scale—we know there is thermal motion of the atoms and molecules at any temperature above absolute zero.) Heat transferred between the electric burner of a stove and the bottom of a pan is transferred by conduction. + Heat conduction occurs by transfer of vibrational energy between molecules, or movement of free electrons. Conduction is particularly important with metals and occurs without observable movement of matter. + On a microscopic scale, conduction occurs as rapidly moving or vibrating atoms and molecules interact with neighboring particles, transferring some of their kinetic energy. + Conduction is the most significant form of heat transfer within a solid object or between solids in thermal contact. + Conduction is most significant in solids, and less though in liquids and gases, due to the space between molecules. Fluids and gases are less conductive than solids. This is due to the large distance between atoms in a fluid or (especially) a gas: fewer collisions between atoms means less conduction. + The rate of heat transfer by conduction is dependent on the temperature difference, the size of the area in contact, the thickness of the material, and the thermal properties of the material(s) in contact. + thermal conductivity: the measure of a material's ability to conduct heat * Some materials conduct thermal energy faster than others. For example, the pillow in your room may the same temperature as the metal doorknob, but the doorknob feels cooler to the touch. In general, good conductors of electricity (metals like copper, aluminum, gold, and silver) are also good heat conductors, whereas insulators of electricity (wood, plastic, and rubber) are poor heat conductors. + examples: - Touching a stove and being burned - Ice cooling down your hand - Boiling water by thrusting a red-hot piece of iron into it CONVECTION: Convection is the heat transfer by the macroscopic movement of a fluid. + This type of transfer takes place in a forced-air furnace and in weather systems, for example. + Convection requires movement on a macroscopic scale; it is therefore confined to gases and liquids. Natural convection occurs when temperature gradients in the system generate localized density differences which result in flow currents. In forced convection, flow currents are set in motion by an external agent such as a stirrer or pump and are independent of density gradients. Higher rates of heat transfer are possible with forced convection compared with natural convection. + Convection is driven by the large scale flow of matter in fluids. Solids cannot transport heat through convection. + Natural convection is driven by buoyant forces: hot air rises because density decreases as temperature increases. This principle applies equally with any fluid. + Convection can transport heat much more efficiently than conduction. Air is a poor conductor and a good insulator if the space is small enough to prevent convection. + Convection often accompanies phase changes, such as when sweat evaporates from your body. This mass flow during convection allows humans to cool off even if the surrounding air's temperature exceeds the body temperature. + Convection is driven by large-scale flow of matter. In the case of Earth, the atmospheric circulation is caused by the flow of hot air from the tropics to the poles, and the flow of cold air from the poles toward the tropics. (Note that Earth's rotation causes changes in the direction of airflow depending on latitude.). + An example of convection is a car engine kept cool by the flow of water in the cooling system, with the water pump maintaining a flow of cool water to the pistons. + For example, the pot of water on the stove in is kept warm in this manner; ocean currents and large-scale atmospheric circulation transfer energy from one part of the globe to another. + examples: - Hot air rising, cooling, and falling (convection currents) - An old-fashioned radiator (creates a convection cell in a room by emitting warm air at the top and drawing in cool air at the bottom). RADIATION: Radiation is the transfer of heat through electromagnetic energy - Heat transfer by radiation occurs when microwaves, infrared radiation, visible light, or another form of electromagnetic radiation is emitted or absorbed. - Energy is radiated from all materials in the form of waves; when this radiation is absorbed by matter it appears as heat. - radiation is important at much higher temperatures than those normally encountered in biological processing - An obvious example is the warming of the Earth by the Sun. - A less obvious example is thermal radiation from the human body. - The energy of electromagnetic radiation depends on the wavelength (color) and varies over a wide range: a smaller wavelength (or higher frequency) corresponds to a higher energy. - All objects emit and absorb electromagnetic energy. The color of an object is related to emissivity, or its efficiency of radiating away energy. Black is the most effective while white is the least effective (e=1 and e=0, respectively). - An ideal radiator, often called a blackbody, is the same color as an ideal absorber and captures all the radiation that falls on it. In contrast, white is a poor absorber and also a poor radiator. A white object reflects all radiation, like a mirror. (A perfect, polished white surface is mirror-like in appearance, and a crushed mirror looks white. ) - The net rate of heat transfer is related to the temperature of the object and the temperature of its surroundings. The larger the difference, the higher the net heat flux. - The temperature of an object is very significant, because the radiation emitted is proportional to this quantity to the fourth power. - All objects absorb and emit electromagnetic radiation. The rate of heat transfer by radiation is largely determined by the color of the object. Black is the most effective, and white the least. - People living in hot climates generally avoid wearing black clothing, for instance. Similarly, black asphalt in a parking lot will be hotter than the adjacent gray sidewalk on a summer day, because black absorbs better than gray. The reverse is also true—black radiates better than gray. Thus, on a clear summer night the asphalt will be colder than the gray sidewalk because black radiates energy more rapidly than gray. - Radiation heat transfer is the energy that is emitted by matter in the form of photons or electromagnetic waves. Radiation can be important even in situations in which there is an intervening medium. An example is the heat transfer that take place between a living entity with its surrounding. - All bodies radiate energy in the form of photons. A photon is the smallest discrete amount of electromagnetic radiation (i.e., one quantum of electromagnetic energy is called a photon). Photons are massless and move in a random direction, with random phase and frequency. - Electromagnetic waves transport energy at the speed of light in empty space and are characterized by their frequency (ν) and wavelength (λ) as follow: λ=Cν, where C is the speed of light in the medium.

Recognize that chemical reactions can be understood in terms of the collisions between ions, atoms, or molecules and the rearrangement of particles.

- Collision theory: describes the mechanism by which chemical reactions occur + In order for an atom or molecule to react with another atom or molecule, they must collide with each other + The collision must be strong enough to break the intramolecular bonds (bonds within a molecule) in the reactants (e.g., the covalent bonds) so that the reaction can occur and new products be formed + Collision theory states that the number of successful or effective collisions is related to the reaction rate. The more successful collisions, the faster the reaction rate. - The collision theory provides us with the ability to predict what conditions are necessary for a successful reaction to take place. These conditions include: + The particles must collide with each other. + The particles must collide with sufficient energy to break the old bonds. --> The amount of energy that reactant particles must have in order to break the old bonds for a reaction to occur is called the activation energy (Ea) + The particles must have proper orientation. - A chemical reaction involves breaking bonds in the reactants, rearranging the atoms into new groupings (the products), and forming new bonds in the products. - The rate, or speed, at which a reaction occurs depends on the frequency of successful collisions. Remember, a successful collision occurs when two reactants collide with enough energy and with the right orientation. That means if there is an increase in the number of collisions, an increase in the number of particles that have enough energy to react, and/or an increase in the number of particles with the correct orientation, the rate of reaction will increase. - The rate of reaction was discussed in terms of three factors: collision frequency, the collision energy, and the geometric orientation. Remember that the collision frequency is the number of collisions per second. The collision frequency is dependent, among other factors, on the temperature of the reaction. TEMPERATURE: When the temperature is increased, the average velocity of the particles is increased. The average kinetic energy of these particles is also increased. The result is that the particles will collide more frequently, because the particles move around faster and will encounter more reactant particles. However, this is only a minor part of the reason why the rate is increased. Just because the particles are colliding more frequently does not mean that the reaction will definitely occur. + The major effect of increasing the temperature is that more of the particles that collide will have the amount of energy needed to have an effective collision. In other words, more particles will have the necessary activation energy. CONCENTRATION: Particles of two gaseous reactants or two reactants in solution have a certain probability of undergoing collisions with each other in a reaction vessel. If you double the concentration of either reactant, the probability of a collision doubles. The rate of reaction is proportional to the number of collisions per unit time. If one concentration is doubled, the number of collisions will also double. Assuming that the percent of collisions that are successful does not change, then having twice as many collisions will result in twice as many successful collisions. The rate of reaction is proportional to the number of collisions over time; increasing the concentration of either reactant increases the number of collisions, and therefore increases the number of successful collisions and the reaction rate. SURFACE AREA: Increasing the surface area of a reactant increases the frequency of collisions and increases the reaction rate. + Several smaller particles have more surface area than one large particle. The more surface area that is available for particles to collide, the faster the reaction will occur. CATALYST: A catalyst is a substance that speeds up the rate of the reaction, without being consumed by the reaction itself. Catalysts are chemicals that increase the rate of a reaction by lowering the activation energy required for the reaction to proceed PRESSURE: When the pressure of a gas is increased its particles are forced closer together, decreasing in the process the amount of empty space between the particles. Therefore, an increase in the pressure of a gas is also an increase in the concentration of the gas. For gaseous reactions, an increase in pressure increases the rate of reaction for the same reasons as described for an increase in concentration. Higher gas pressure leads to a greater number of collisions between reacting particles.

Apply knowledge of the development and organization of the periodic table and predict the properties of elements on the basis of their positions in the periodic table.

- Dmitri Mendeleev: table ordering the elements by their atomic number (number of protons) - Columns: groups (have similar properties) - Rows: periods o Alkali metals (group 1): soft, silvery, react violently with water to form a basic/alkaline solution o Alkaline earth metals (group 2): shiny, silvery white o Halogens (group 17): very reactive and poisonous, commonly found in bleach/disinfectants o Noble gases (group 18): colorless, odorless, unreactive; found in lightbulbs - nonmetals: halogens, hydrogen, and nonmetals o Metals: shiny, good conductors of heat and electricity, malleable, ductile - alkali and alkaline earth metals - transition metals (group 3-12) - basic metals: under staircase in groups 13-16 o Nonmetals: brittle in solid form, dull, poor conductors of heat and electricity, lower melting and boiling points than metals (gases at room temp usually). above staircase: C, N, O, F, P, S, Cl, Se, Br, I o Metalloids: found on the staircase; have properties of metals and nonmetals (B, Si, Ge, As, Sb, Te, At) o Lanthanoids: continuation of row 6 o actinoids: continuation of row 7 TRENDS: the trends are a result of (1) the charge inside the nucleus and (2) the number of electrons in the valence shell; (3) shielding: as the number of electron shells increases, they have the effect of shielding the attractive charge from the nucleus and reducing the electrostatic attraction between the positive protons and negative electrons ATOMIC RADIUS: the distance from the nucleus to the edge of the electron cloud or half the distance between two identical atoms' nuclei in a covalent bond + As you move from top to bottom in the same group, the atomic radius with INCREASE because new energy levels are needed to hold the electrons, resulting in a larger atom + As you move from left to right in the same period, the atomic radius will DECREASE because they have the same number of energy levels but more positive protons in the nucleus that will have a greater pull on the negative electrons, bringing them farther in IONIZATION ENERGY: the amount of energy required to remove an electron from an atom; the first ionization energy is the energy required to remove one mole of the most loosely held electrons from one mole of neutral atoms to produce one mole of ions each with a charge of +1. the amount of energy it takes for all the atoms in a mole to lose one electron each + As you move from top to bottom in the same group, the ionization energy DECREASES (it will be easier to remove an atom's outer electron) because the electrons are farther from the nucleus as atoms increase in size (holding it less tightly) + As you move from left to right in the same period, the ionization energy INCREASES (it will be harder to remove an atom's outer electron) because the electrons are located in the same energy levels, so protons will have a greater pull on those outer electrons, making it harder to remove them ELECTRONEGATIVITY: the ability an atom has to attract other electrons (higher electronegativity = attract/steal more atoms) the ability to attract a pair of bonding electrons in a chemical bond. It affects how atoms share electrons when forming a chemical bond and this in turn affects the properties of the product produced in a reaction + As you move from top to bottom in the same group, the electronegativity DECREASES because the increased number of energy levels/atomic radius puts the outer electrons further away from the pull of the nucleus + As you move from left to right in the same period, the electronegativity INCREASES because there are more positive protons in the nucleus, creating a stronger pull on the negative electrons in the outer shell ELECTRON AFFINITY: the ability of an atom to accept an electron to form a negative ion; the energy change that occurs when an electron is accepted by an atom in the gaseous state to form an ion with a charge of -1 + As you move from top to bottom in the same group, the electron affinity DECREASES because the electrons are in higher energy level far from the nucleus, so there's less pull + As you move from left to right in the same period, the electron affinity INCREASES because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons BOILING POINT: the temperature that a substance changes from the liquid to gas phase; tend to INCREASE and then DECREASE as you move from left to right (high point around tungsten area) + metals that are all solids at room temperature and they're going to have higher boiling points than nonmetals which are all gases at room temperature METALLIC CHARACTER: shiny, silvery, good conductor of heat and electricity, and able to bend without cracking. Weaker attraction between electrons and nucleus means the more delocalized they are (wander around) --> valence electrons are loosely held --> ability of electrons to move about is the reason why metals are so conductive of heat and electricity + Metallic character DECREASES from left to right and INCREASES as you move down a group --> elements that have a weaker hold on their electrons are going to have more metallic character

Demonstrate knowledge of kinetic and potential energy.

- Energy: the ability to do work + Scalar: no direction and is described by magnitude alone - All energy in the universe falls into two main types: kinetic and potential. + Kinetic energy is the energy of motion. Any object in motion has kinetic energy and is using kinetic energy every moment it is moving. Kinetic energy can vary in quantity depending on the mass of an object and how fast it is moving. Therefore mass and speed factor into the kinetic energy of an object. ** Objects with less mass have less kinetic energy than objects with more mass moving at the same speed. Ek or KE = ½ mv2 where E is energy (J or Nm), m is mass (kg) and v is speed (m/s) - Work is the change in KE of a system: Wnet = Δ Ek - The energy associated with an object's motion is called kinetic energy. A speeding bullet, a walking person, and electromagnetic radiation like light all have kinetic energy. Another example of kinetic energy is the energy associated with the constant, random bouncing of atoms or molecules. This is also called thermal energy - the greater the thermal energy, the greater the kinetic energy of atomic motion, and vice versa. The average thermal energy of a group of molecules is what we call temperature, and when thermal energy is being transferred between two objects, it's known as heat. + Potential energy is energy an object has due to its position or arrangement. It is present when an object's position results in the storage of energy that can be used at some point in the future. Positions that result in potential energy storage include objects located at heights above ground level, stretched positions of elastic objects, and configurations of charged objects that generate an expected response when they interact. These are referred to as gravitational potential energy, elastic potential energy, and electrical potential energy (Electric potential energy is the energy that is needed to move a charge against an electric field). All potential energy is commonly known as 'stored energy,' since it is present but not being used at the moment. - Potential energy (Ep): stored energy which has the potential to be used to do work - Ex: chemical and nuclear energy; chemical energy is stored in the bonds between atoms and can be released during a chemical reaction; nuclear energy is stored in the bonds between nucleons (protons and neutrons) in the nucleus of an atom and when they're broken they can release a bunch of energy - all systems possess a state of lowest potential energy. this state is called equilibrium. to move a system out of equilibrium a force must be applied to the system to do work on it,. once work has been done on the system, it has potential energy due to its new position outside of equilibrium. when a system is out of equilibrium, there is a force associated with returning the system to its rest state. the force is called the restoring force. in oscillating systems such as pendulums, the restoring force is the force responsible for the oscillations. the restoring force on the pendulum in F = -mgsinθ where θ is the angle between the bob at equilibrium and maximum displacement * Gravitational potential energy (Eg): energy stored due to an object's position above the ground; any elevated object has energy potential due to gravity Eg = mgh Where m is the mass of the object (kg), g is acceleration due to gravity (m/s2), and h is the height of the object (m) * Elastic potential energy (Ee): potential energy stored in an object that is stretched or deformed: PE = 1/2kx^2 where k is the spring constant in N/m, x is the extension in meters, and Ee is the elastic potential energy in joules Work: W = Fdcosθ where W is work in (J) or Nm or kg m2/s2, d is displacement (m), F is force in N or kg m/s2 - Work can be negative when force is applied in the opposite direction of the displacement of the object because θ becomes 180 degrees which is -1 - work is the energy transferred to or from an object via the application of force along a displacement. - If the force is parallel to the direction of motion, it's just W=Fd Power is the rate at which work is done: P = W/t where P is power in watts (aka J/s)

Demonstrate knowledge of how the transfer of energy as heat is related to changes in temperature and interpret the direction of heat flow in a system.

- First law of thermodynamics (specific version of law of conservation of energy): applied to systems where heat transfer and work are the means by which energy is transferred into and out of a system. It states that any change in the energy of a system (ΔU) is equal to the net transfer of heat from or to the system (Q) plus the net work done on or by the system (W) ΔU = Q -W + Value for W is negative because work is being done BY the system, moving energy OUT of the system + Value for W is positive when work is being done TO the system (ΔU = Q + W) - Second law of thermodynamics: entropy always increases over time; order tends to disorder + Entropy: a measure of how much the energy is spread out in a system. The energy is not available to do work. Entropy in the universe NEVER decreases, it will eventually increase to a point where all energy is evenly dispersed (maximum entropy) + Entropy can be reduced in a closed system, but always by increasing entropy in the wider universe - zeroth law of thermodynamics says that no heat is transferred between two objects in thermal equilibrium; therefore, they are the same temperature. - temperature: a measure of the average kinetic energy of the atoms or molecules in a system. + when a system absorbs or loses heat, the average kinetic energy of the molecules will change. Thus, heat transfer results in a change in the system's temperature as long as the system in not undergoing a phase change. - we can calculate the heat released or absorbed using the specific heat capacity, C, the mass of the substance m, and the change in temperature ΔT using the equation: q = m x C x ΔT + q or Q is Heat (unit: joules); heat is thermal energy transferred between two systems at different temperatures that come into contact (thermal energy is transferred from a hotter system to a cooler system in contact). - If q is POSITIVE (energy of the system increases), then our system increases in temperature and T(final) > T(initial) - If q is NEGATIVE (energy of the system decreases), then our system decreases in temperature and T(final) < T(initial) + C: specific heat capacity (specific heat) is how much energy is needed to increase the temperature of one gram of a substance by 1 degree C or 1 K; in units J/(g x K). The heat capacity tells us how much energy is needed to change the temperature of a given substance assuming that no phase change is occurring. - example: let's say that we have 250 mL of hot tea which we would like to cool down before drinking it. the tea is currently at 370 K, and we'd like to cool it down to 350 K. How much thermal energy has to be transferred from the tea to the surroundings to cool the tea? + The specific heat of water is 4.18 J/(g x K), and the density of water is 1.00 g/mL. 1) calculate the mass of the substance: m = 250mL x 1.00 g/mL = 250 g 2) calculate the change in temperature (ΔT): ΔT = T(final) - T(initial) = 350 -370 K = -20 K (since the temperature of the tea is decreasing and ΔT is negative, we would expect q to also be negative since our system is losing thermal energy. 3) solve for q: q = m x C x ΔT = 250 g x 4.18 J/(g x K) x -20 K = -21000 J. Thus we calculated that the tea will transfer 21000 J of energy to the surroundings when it cools down from 370 K to 350 K - example: a 0.500 kg aluminum pan on a stove is used to heat 0.250 L of water from 20 C to 80 C. (a) how much heat is required? what percentage of the heat is used to raise the temperature of (b) the pan and (c) the water? 1) calculate the temperature difference: ΔT = T(final) - T(initial) = 80C -20C = 60C 2) calculate the mass of the water: because the density of water is 1000 kg/m^3, one liter of water has a mass of 1 kg, and the mass of 0.250 L of water is 0.250 kg 3) calculate the heat transfer to the water, using the specific heat of water. Q(w) = m(w)c(w)ΔT = 0.250kg x 4186 J/kgC x 60C = 62.8 kJ 4) calculate the heat transferred to the aluminum: Q(Al) = m(Al)c(Al)ΔT = (0.500 kg)(900 J/kgC)(60 C) = 27 kJ 5) compare the percentage of heat going into the pan versus that going into the water. First, find the total transferred heat: Q (total) = Q(water) + Q(aluminum) = 62.8 kJ +27 kJ = 89.8 kJ - Thus the amount of heat going into heating the pan is: 27/89.8 = 30.1% - The amount of heat going into heating the water is 62.8/89.8 = 69.9% example: suppose you pour 0.250 kg of 20C water into a 0.500 kg aluminum pan off the stove with a temperature of 150 C. Assume that the pan is placed on an insulated pan and that a negligible amount of water boils off. what is the temperature when the water and pan reach thermal equilibrium a short time later? 1) use the equation for heat transfer Q = mcΔT to express the heat lost by the aluminum pan: Q(hot) = m(Al) x c(Al) x ((T(final) -150C) 2) express the heat gained by the water: Q(cold) = m(w) x c(w) x (T(final) -20C) 3) Q (cold) + Q(hot) = 0 because the heat lost by the hot pan is gained by the cold water: Q(cold) = - Q(hot) m(w) x c(w) x (T(final) -20C) = - m(Al) x c(Al) x ((T(final) -150C) 4) solve for T(final): T (final) = (m(Al)c(Al)(150C) + m(w)c(w)(20C))/(m(Al)c(Al) + m(w)c(w)) = 59.1C - example: calculate the temperature increase of a 100 kg of brake material with an average specific heat of 800 J/kgC of the material retains 10% of the energy from a 10,000 kg truck descending 75 m (in vertical displacement) at a constant speed. - if the brakes are not applied, gravitational potential energy is converted into kinetic energy. when brakes are applied, gravitational potential energy is converted into internal energy of the brake material. we first calculate the gravitational potential energy (mgh) that the entire truck loses in its descent and then find the temperature increase produced in the brake material alone. 1) calculate the change in gravitational potential energy as the truck goes downhill: mgh = (10,000 kg)(9.8 m/s^2)(75 m) = 7.35 x 10^6 J 2) calculate the temperature from the heat transferred: ΔT= Q/mc = (7.35 x 10^6 J)/(100 kg x 800 j/kgC) = 92 C - enthalpy is the energy transferred during a chemical reaction. The Law of Conservation of Energy tells us that energy is neither created nor destroyed. It is transferred from one form to another. Temperature and heat are not the same. Temperature is a measure of the random motion of particles in the system, and heat is the transfer of energy due to a temperature difference. - In an exothermic reaction, the potential energy of the system goes down, and heat is given out. In an endothermic reaction, the potential energy of the system goes up, and heat is taken in. The enthalpy change of a reaction is the difference between the sum of enthalpies of products and the sum of enthalpies of reactants, and the amount of heat exchanged with the surroundings can be directly related to the enthalpy change of the reaction.

Apply knowledge of Newton's laws of motion and law of universal gravitation and recognize the relationship between these laws and the laws of conservation of energy and momentum.

- Force: a push, pull, or twist acting on an object that can cause objects to move, speed up, slow down, change direction, change shape - Measured in Newtons: kg m/s2 - Newton's first law (law of inertia): an object at rest stays at rest and an object in motion stays in motion (same speed and direction - velocity) unless acted upon by an unbalanced force; describes an object's resistance to change + Only an unbalanced force will cause an object to accelerate by changing its speed, direction, or both speed and direction + Static equilibrium: objects at rest + Dynamic equilibrium: object in motion with a constant velocity + Inertia: the natural tendency of an object to resist changes in its state of motion - Newton's second law: the amount of acceleration is directly proportional to the net force acting on the object; F = ma + Net force: the sum of all forces acting on an object in a particular direction + Applies to the behavior of objects for which all existing forces are not balanced and states the acceleration of an object is dependent upon the net force acting upon the object and the mass of the object + Acceleration of the object is directly proportional to the net force applied to it and inversely proportional to the mass of the object: the greater the force applied, the greater the acceleration and the more massive the object, the slower the acceleration + Mass: measures the amount of matter (atoms) making up an object (kg) * Vs weight: the measurement of the pull of gravity on an object, so it is also called the force due to gravity (N) --> Weight = mg. On earth: F=ma --> (70 kg)(9.8 m/s2) = 686 N + Centripetal acceleration: an object traveling at constant speed in a circular path experiences acceleration because the direction of velocity is always changing. Acceleration is in the direction of the change in velocity, which points directly to the center of the circular path * a = v2/r * F = mv2/r - Newton's third law: for every action force there is an equal and opposite reaction force + All forces come in pairs; no force exists in isolation + When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body - Law of universal gravitation: two objects attract each other with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them: F = G * (m1*m2) /d2, where F is the gravitational force, G is the universal gravitational constant 6.67 x 10-11 Nm2/kg2, m is the mass of each object, and d is the distance between their centers. + Inverse square law: increasing the distance only a small amount decreases the force by a large amount because the square of the distance is inversely proportional to the force + Gravity gets weaker with distance + Every object in the universe attracts every other object with a force that is directed along a line joining them. The force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them - Law of conservation of energy: in a closed system, total energy is conserved/constant + KE1 + PE1 = KE2 + PE2 + KE = ½ mv2 + PE = mgh + ½ mv2 + mgh = ½ mv2 + mgh + Newton's second law? - Law of conservation of momentum: For an isolated system with any number of objects in it, the total momentum is conserved. (Ptot = constant) + Momentum: mass in motion --> if an object is moving, it has momentum (p) + Momentum is always conserved as long as there are no forces outside the immediate situation affecting the colliding objects + p = mv with units kg m/s + Newton's second law: The net external force equals the change in momentum of a system divided by the time over which it changes. --> Fnet = Δp/Δt ++ Fnet = Δp/Δt = mΔv/Δt --> Δv/Δt = acceleration (a) so Fnet = ma + Newton's third law: F2 = -F1 so Δp2 = -F1Δt = -Δp1 --> ++ Δp1 + Δp2 = 0 ++ p1 + p2 = p1' + p2' + In the case of conservation of momentum, the total momentum in the system remains the same before and after the collision + Impulse (J) =FΔt = Δmv with units Ns (newton seconds) --> the effect of a force acting on an object over some time period ++ Δp1 = F1Δt and Δp2 = F2Δt ++ Newton's second law: F = ma --> a = Δv/Δt so F = Δ(mv)/Δt --> multiply both sides by Δt and you get FΔt = Δmv + Elastic collisions: objects separate after impact and don't lose any of their kinetic energy (energy of motion); momentum and KE are conserved ++ p1 + p2 = p1' + p2' (Fnet = 0) ++ m1v1 + m2v2 = m1v1' + m2v2' + Inelastic collisions: objects stick together after impact, and momentum IS conserved but kinetic energy is NOT conserved --> the forces between colliding objects may convert KE to other forms of energy (PE or thermal energy) ++ m1v1 + m2v2 = m1v1' + m2v2' but since the two objects stick together after colliding, they move together at the same speed so the conservation of momentum equation becomes m1v1 + m2v2 = (m1 + m2)v'

Demonstrate knowledge of how energy and information are transferred by waves without mass transfer, including recognizing technology that employ this phenomenon.

- This is because waves transfer energy and not mass. For example, a wave in the ocean doesn't transfer water particles from one place to another, but rather those particles are just moving up and down perpendicular to, or at a right angle to, the movement of the horizontal wave. This happens as energy is transformed from potential or 'stored' energy to kinetic or 'movement' energy, and then back to potential energy again. - energy is transferred through the vibrations of the medium's particles. So a water wave transfers energy through the vibration of the water particles, sound waves travel through the vibration of air particles or the particles of a liquid or solid, and electromagnetic and magnetic fields vibrate to transfer energy through electromagnetic waves. - not all waves are the same size, shape, or speed. So as frequency increases (meaning more waves are produced), the wavelength decreases. And as frequency decreases (fewer waves are produced) the wavelength increases. - radio waves: radio waves have a much lower frequency and longer wavelength, meaning they have less energy. + MRI uses magnetic fields and radio waves to measures how much water is in different tissues of the body, maps the location of the water and then uses this information to generate a detailed image. + Radio receivers detect radio waves and transform them into sounds we can hear. each radio transmitting station broadcasts a radio wave with a unique frequency called the carrier wave. When there is an audio signal (human/music) to be sent out, that signal is using the transmitting equipment to modify the carrier wave slightly (modulation) ** AM (amplitude modulation): the amplitude of the carrier wave is changed. AM wavelengths are much longer than FM wavelengths, so they are less affected by structures like buildings/mountains so they have a greater range ** FM (frequency modulation): the frequency of the carrier wave is changed. More than one signal can be transported by the carrier wave and it enables better reproduction of the original modulating wave + Submarines: need to evade detection but still need communication --> radio waves don't penetrate very far into seawater but still need to communicate: submarines receive VLF (very low frequency) and ELF (extremely low frequency) radio which can penetrate seawater. VLF has very slow data download rates - transmitting information: + Waves transfer energy but not matter. Using technology, the basic features of waves can be manipulated so that they can also rapidly convey vast amounts of information over very large distances. Waves convey information in 2 general ways: 1) Information about a medium can be obtained simply by the way a wave is affected as it travels through that medium (seismic waves, MRIs, X-rays) 2) Waves can be used as a vehicle for transmitting information (radio waves) - microwaves: + cell phones: cell phones produce microwaves in a similar way to a radio transmitter. Electrons oscillate in the cell phones' antenna, producing microwaves. These are sent in all directions and are received by the nearest cellular tower, which sends the signal to the appropriate transmitter tower. The transmitting tower broadcasts in the microwave signal which the receiving cellular phone receives via its own antenna. Once the signal is established microwaves are transmitted back and forth between the two phones and the cellular towers at a specific frequency. In order for this to work, cellular phones constantly send and receive signals to and from nearby cellular towers so that the network knows where the phone is. + Microwaves: the microwave produces microwaves using a magnetron. The microwaves are directed into the food compartment of the microwave. Here, the waves cause water molecules to oscillate rapidly back and forth, which results in heating (heat is a measure of the vibrations of particles). Heat is transferred into the middle of the food by conduction. - X-rays: + X-rays: are used to see the bones (hard tissue) inside your body have a lot of energy because they have a high frequency and a short wavelength. can pass through soft tissue but not hard tissue of bones. + x-rays are produced by accelerating electrons in a magnetic field and have them collide with a metal target. The electron loses energy as an x-ray as it suddenly decelerates. + X-rays can pass through tissues and expose photographic film. The x-rays are absorbed by dense body tissues (bones) which appear as white areas, but they pass easily through less dense tissues (muscle), which appear dark. Used to identify fractures and abnormalities in bone + X-ray radiographs are produced by projecting a beam of X-rays toward an object, in medical cases, a part of the human body. Depending on the physical properties of the object (density and composition), some of the X-rays can be partially absorbed. The portion of the rays that are not absorbed then pass through the object and are recorded by either film or a detector, like in a camera. This provides the observer with a 2-dimensional representation of all the components of that object superimposed on each other. - gamma rays: Radionuclide scanning involves introducing a radioactive substance (radionuclide) into the body where it is taken up in different amounts by different tissues. Gamma rays emitted by the tissues that take up the radionuclide are detected by a gamma camera. Unlike x-rays which pass through the patient, the radiation comes from inside the patient - infrared radiation: Thermal imagining using IR which is emitted by all objects with a temperature above absolute zero --> can see with or without visible light This refers to the fact that energy in concentrated form is useful for generating electricity, moving or heating objects, and producing light, whereas diffuse energy in the environment is not readily captured for practical use. Therefore, to produce energy typically means to convert some stored energy into a desired form—for example, the stored energy of water behind a dam is released as the water flows downhill and drives a turbine generator to produce electricity, which is then delivered to users through distribution systems. Seeing with sound: - Sound can also be used as a diagnostic tool to see into the human body and to produce images of the seabed using sonar - Ultrasound is a diagnostic tool for visualizing internal structures without surgery or x-rays. Ultrasound imaging is based on the fact that tissues of different densities reflect sound waves differently. Sound waves are directed towards a structure and the reflected sound waves are recorded. - Sonar: used to image objects in water, sound is transmitted from an acoustic array and the echo is received by a receiver. Used for military applications (submarine), commercial fish finding, depth sounding, and mapping the seafloor and underwater archeology. Higher frequencies give greater image resolution

Demonstrate knowledge of the energy changes that accompany changes in states of matter.

- the temperature of a substance increases as it is heated. Temperature is the average kinetic energy of the substance, where energy is the ability to do work. Heat is the total energy contained within a substance. As a solid is heated, its temperature increases as the molecules move faster. During the phase change, when solid melts into liquid, its temperature remains constant as the heat energy is stored as potential energy. Likewise, as heat is added to a liquid, its temperature increases as the molecules, once again, move faster. When the liquid reaches its boiling point and boils, the temperature remains constant as, once again, the added heat is stored as potential energy during the phase change. Finally, impurities will change the melting point and the boiling point of compounds. - Fusion, vaporization, and sublimation are endothermic processes, whereas freezing, condensation, and deposition are exothermic processes. - Changes of state are examples of phase changes, or phase transitions. - All phase changes are accompanied by changes in the energy of a system. Changes from a more-ordered state to a less-ordered state (such as a liquid to a gas) are endothermic. Changes from a less-ordered state to a more-ordered state (such as a liquid to a solid) are always exothermic. - The conversion of a solid to a liquid is called fusion (or melting). The energy required to melt 1 mol of a substance is its enthalpy of fusion (ΔHfus). - The energy change required to vaporize 1 mol of a substance is the enthalpy of vaporization (ΔHvap). - The direct conversion of a solid to a gas is sublimation. The amount of energy needed to sublime 1 mol of a substance is its enthalpy of sublimation (ΔHsub) and is the sum of the enthalpies of fusion and vaporization. - Plots of the temperature of a substance versus heat added or versus heating time at a constant rate of heating are called heating curves. Heating curves relate temperature changes to phase transitions. - A superheated liquid, a liquid at a temperature and pressure at which it should be a gas, is not stable. - A cooling curve is not exactly the reverse of the heating curve because many liquids do not freeze at the expected temperature. Instead, they form a supercooled liquid, a metastable liquid phase that exists below the normal melting point. Supercooled liquids usually crystallize on standing, or adding a seed crystal of the same or another substance can induce crystallization. 𝑄=𝑚𝐿f (melting/freezing) 𝑄=𝑚𝐿v (vaporization/condensation) 𝑄=𝑚𝐿s (sublimation/deposition) where the latent heat of fusion, 𝐿f and and latent heat of vaporization, 𝐿v; Latent heat is measured in units of J/kg; latent heat of sublimation 𝐿s - Energy is required to partially overcome the attractive forces between molecules in a solid to form a liquid. That same energy must be removed for freezing to take place. - Molecules are separated by large distances when going from liquid to vapor, requiring significant energy to overcome molecular attraction. The same energy must be removed for condensation to take place. - There is no temperature change until a phase change is complete. - A graph of temperature versus energy added. The system is constructed so that no vapor evaporates while ice warms to become liquid water, and so that, when vaporization occurs, the vapor remains in of the system. The long stretches of constant temperature values at 0ºC and 100ºC reflect the large latent heat of melting and vaporization, respectively. The heat Q required to change the phase of a sample of mass m is given by Q=mLfQ=mLf (melting or freezing) and Q=mLvQ=mLv (evaporating or condensing), where Lf and Lv are the latent heat of fusion and the latent heat of vaporization, respectively. latent heat of fusion: the energy required to transition one unit of a substance from solid to liquid; equivalently, the energy liberated when one unit of a substance transitions from liquid to solid. latent heat of vaporization: the energy required to transition one unit of a substance from liquid to vapor; equivalently, the energy liberated when one unit of a substance transitions from vapor to liquid. - example: 3 ice cubes are used to chill a soda at 20C with mass 0.25 kg. the ice is at 0C and each ice cube has a mass of 6 g. assume that the soda has the same heat capacity as water. find the final temperature when all the ice has melted. + heat is transferred from the soda to the ice for melting. The melting of ice occurs in 2 steps: first the phase change occurs and solid (ice) transforms into liquid water at the melting temperature, then the temperature of this water rises. melting yields water at 0C, so more heat is transferred from the soda to this water until the water plus soda reaches thermal equilibrium. Q(ice) = - Q(soda) - the heast transferred to the ice is Q(ice)= m(ice)Lf + m(ice)c(water)(Tf - 0C) - the heat given off by the soda is Q(soda) = m(soda)c(water)(Tf - 20C) m(ice)Lf + m(ice)c(water)(Tf - 0C) = -m(soda)c(water)(Tf - 20C) Tf = ( m(soda)c(water)(20C) - m(ice)Lf )/( (m(soda) + m(ice)c(water) ) - the mass of ice is 3 x 6 kg = 0.018 kg - Tf = 13C Enthalpy changes that accompany phase transitions are indicated by purple and green arrows. Enthalpy: - endothermic: ΔH > 0; ΔH is positive for any transition from a more ordered to a less ordered state; requires an input of energy + fusion: solid to liquid + vaporization: liquid to gas + sublimation: solid to gas - exothermic: ΔH < 0; ΔH is negative for a transition from a less ordered to a more ordered state; releases energy + condensation: gas to liquid + freezing: liquid to solid + deposition: gas to solid - Phase changes are always accompanied by a change in the energy of a system. - For example, converting a liquid, in which the molecules are close together, to a gas, in which the molecules are, on average, far apart, requires an input of energy (heat) to give the molecules enough kinetic energy to allow them to overcome the intermolecular attractive forces. The stronger the attractive forces, the more energy is needed to overcome them. Solids, which are highly ordered, have the strongest intermolecular interactions, whereas gases, which are very disordered, have the weakest. Thus any transition from a more ordered to a less ordered state (solid to liquid, liquid to gas, or solid to gas) requires an input of energy; it is endothermic. Conversely, any transition from a less ordered to a more ordered state (liquid to solid, gas to liquid, or gas to solid) releases energy; it is exothermic. The energy change associated with each common phase change is shown in Figure · Figure: A Heating Curve for Water. This plot of temperature shows what happens to a 75 g sample of ice initially at 1 atm and −23°C as heat is added at a constant rate: A-B: heating solid ice; B-C: melting ice; C-D: heating liquid water; D-E: vaporizing water; E-F: heating steam. · Figure: A Cooling Curve for Water. This plot of temperature shows what happens to a 75 g sample of steam initially at 1 atm and 200°C as heat is removed at a constant rate: A-B: cooling steam; B-C: condensing steam; C-D: cooling liquid water to give a supercooled liquid; D-E: warming the liquid as it begins to freeze; E-F: freezing liquid water; F-G: cooling ice.

Compare and contrast the transmission, reflection, and absorption of light in matter.

- white light contains all of the wavelengths/colors of visible light + the color of an object depends on which wavelengths of light it absorbs and which is reflects. white objects reflect all of the light that hits them and absorbs none. black objects reflect none but absorbs all of the light that hits them. A red surface absorbs all of the wavelengths except for red, which is reflected. + the sky looks blue because the white light from the sun hits the molecules in our atmosphere and causes the shorter blue wavelengths to scatter out in all directions - When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object's material and the frequency (color) of the light ABSORPTION: When light is absorbed, the energy is taken in by the material. The energy within the material increases, causing the particles to move faster. This energy eventually radiates as heat. - Ex: heat rising from pavement after the sun has been shining on it for awhile - Absorption occurs when photons from incident light hit atoms and molecules and cause them to vibrate. The more an object's molecules move and vibrate, the hotter it becomes. This heat is then emitted from the object as thermal energy. - Some objects, such as darker colored objects, absorb more incident light energy than others. For example, black pavement absorbs most visible and UV energy and reflects very little, while a light-colored concrete sidewalk reflects more energy than it absorbs. Thus, the black pavement is hotter than the sidewalk on a hot summer day. Photons bounce around during this absorption process and lose bits of energy to numerous molecules along the way. This thermal energy then radiates in the form of longer wavelength infrared energy. REFLECTION: When light is reflected, the material fails to absorb the energy from the light and the light rays are redirected. - Ex: a mirror - Reflection is when incident light (incoming light) hits an object and bounces off. Very smooth surfaces such as mirrors reflect almost all incident light. - The color of an object is actually the wavelengths of the light reflected while all other wavelengths are absorbed. Color, in this case, refers to the different wavelengths of light in the visible light spectrum perceived by our eyes. The physical and chemical composition of matter determines which wavelength (or color) is reflected. TRANSMITTED: When light waves are transmitted, the incoming light passes through the material unchanged. Light waves come out of the material at the SAME angle they entered. - Ex: a transparent material like glass - If the object is transparent, then the vibrations of the electrons are passed on to neighboring atoms through the bulk of the material and reemitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. REFRACTION: Refracted light is similar to transmitted light. The incoming light again passes through the transparent material, but due to difference in the optical properties of materials and boundary angles, the light comes out at a different angle - Ex: when light from an object is seen after passing through a glass of water. The image is distorted - Refraction is when light waves change direction as they pass from one medium to another. Light travels slower in air than in a vacuum, and even slower in water. As light travels into a different medium, the change in speed bends the light. Different wavelengths of light are slowed at different rates, which causes them to bend at different angles. Pure Light and Light Dispersion: (a) A pure wavelength of light falls onto a prism and is refracted at both surfaces. (b) White light is dispersed by the prism (shown exaggerated). Since the index of refraction varies with wavelength, the angles of refraction vary with wavelength. A sequence of red to violet is produced, because the index of refraction increases steadily with decreasing wavelength. - A prism works because the different colors of light travel at different speeds inside the glass. Because the colors of light travel at different speeds, they get bent by different amounts and come out all spread out instead of mixed up. Violet travels the slowest so it is on the bottom and red travels the fastest so is on the top. This is because what is called the index of refraction, (the ratio of the speed of light in a vacuum to the speed of light in a material), is increased for the slower moving waves (i.e. violet). The higher index of refraction means that violet light is the most bent, and red is then the least bent because of its lower index of refraction, and the other colors fall somewhere in between.

Demonstrate knowledge of how energy is stored and can change in electric and magnetic fields.

Electricity and magnetism are inextricably linked. Under certain conditions, electric current causes a magnetic field. Under other conditions, a magnetic field can cause an electric current. A moving charged particle creates a magnetic field around it. Additionally, when a moving charged particle moves through a different magnetic field, the two magnetic fields will interact. The result is a force exerted on the moving charged particle. - The energy of a capacitor is stored in the electric field between its plates. Similarly, an inductor has the capability to store energy, but in its magnetic field. - Electric forces and magnetic forces are different aspects of a single electromagnetic interaction. Such forces can be attractive or repulsive, depending on the relative sign of the electric charges involved, the direction of current flow, and the orientation of magnets. The forces' magnitudes depend on the magnitudes of the charges, currents, and magnetic strengths as well as on the distances between the interacting objects. All objects with electrical charge or magnetization are sources of electric or magnetic fields and can be affected by the electric or magnetic fields of other such objects. Attraction and repulsion of electric charges at the atomic scale explain the structure, properties, and transformations of matter and the contact forces between material objects. Coulomb's law provides the mathematical model to describe and predict the effects of electrostatic forces (relating to stationary electric charges or fields) between distant objects. Coulomb's law gives the magnitude of force between point charges: F = k x | q1*q2 |/r^2 where q1 and q2 are two point charges separated by distance r and k is 8.99 x 10^9 N*m^2/C^2 - Electric and magnetic fields also contain energy; any change in the relative positions of charged objects (or in the positions or orientations of magnets) changes the fields between them and thus the amount of energy stored in those fields. When a particle in a molecule of solid matter vibrates, energy is continually being transformed back and forth between the energy of motion and the energy stored in the electric and magnetic fields within the matter. Matter in a stable form minimizes the stored energy in the electric and magnetic fields within it; this defines the equilibrium positions and spacing of the atomic nuclei in a molecule or an extended solid and the form of their combined electron charge distributions (e.g., chemical bonds, metals). Energy is also stored in the electric fields between charged particles and the magnetic fields between magnets, and it changes when these objects are moved relative to one another. - A magnetic field produces an electric current, as long as the magnetic field is changing. This is called Faraday's law. - Electric and magnetic fields also contain energy; any change in the relative positions of charged objects (or in the positions or orientations of magnets) changes the fields between them and thus the amount of energy stored in those fields. When a particle in a molecule of solid matter vibrates, energy is continually being transformed back and forth between the energy of motion and the energy stored in the electric and magnetic fields within the matter. Matter in a stable form minimizes the stored energy in the electric and magnetic fields within it; this defines the equilibrium positions and spacing of the atomic nuclei in a molecule or an extended solid and the form of their combined electron charge distributions (e.g., chemical bonds, metals). Energy stored in fields within a system can also be described as potential energy. For any system where the stored energy depends only on the spatial configuration of the system and not on its history, potential energy is a useful concept (e.g., a massive object above Earth's surface, a compressed or stretched spring). It is defined as a difference in energy compared to some arbitrary reference configuration of a system. For example, lifting an object increases the stored energy in the gravitational field between that object and Earth (gravitational potential energy) compared to that for the object at Earth's surface; when the object falls, the stored energy decreases and the object's kinetic energy increases. When a pendulum swings, some stored energy is transformed into kinetic energy and back again into stored energy during each swing. (In both examples energy is transferred out of the system due to collisions with air and for the pendulum also by friction in its support.) Any change in potential energy is accompanied by changes in other forms of energy within the system, or by energy transfers into or out of the system. - Electromagnetic radiation (such as light and X-rays) can be modeled as a wave of changing electric and magnetic fields. At the subatomic scale (i. e., in quantum theory), many phenomena involving electromagnetic radiation (e.g., photoelectric effect) are best modeled as a stream of particles called photons. Electromagnetic radiation from the sun is a major source of energy for life on Earth. electric fields: An electric field is a map of the electric force over a particular area. "electrical energy" may mean energy stored in a battery or energy transmitted by electric currents. electric field: A region of space around a charged particle, or between two voltages; it exerts a force on charged objects in its vicinity. - An electric field is the force that fills the space around every electric charge or group of charges. There are two types of electric fields: static (or electrostatic) fields and dynamic (or time-varying) fields. Electric fields have a definite magnitude and specific direction. The magnitude (or strength) of the electric field at any point is given by the equation, E = F / q, the force experienced by the charge at that point divided by the charge. it is the force per unit charge. Here, E is the electric field strength in newtons per coulomb, F is the force on the charge q measured in newtons, and q is the charge you're putting in the field, measured in coulombs. - Examples of electric fields include the field produced in the dielectric of a parallel-plate capacitor (which creates an electrostatic field) and the electromagnetic wave produced by a radio broadcast monopole antenna (which creates a time-varying field). - The energy stored in a capacitor is electrostatic potential energy and is thus related to the charge Q and voltage V between the capacitor plates. A charged capacitor stores energy in the electrical field between its plates. As the capacitor is being charged, the electrical field builds up. When a charged capacitor is disconnected from a battery, its energy remains in the field in the space between its plates. - magnetic field: A condition in the space around a magnet or electric current in which there is a detectable magnetic force, and where two magnetic poles are present. The energy stored in a magnetic field is equal to the work needed to produce a current through the inductor. Magnetic fields are generated by moving charges or by changing electric fields. + Right hand rules: 1) Right-Hand Rule #1 determines the directions of magnetic force, conventional current and the magnetic field. Given any two of theses, the third can be found. Using your right-hand: point your index finger in the direction of the charge's velocity (moving charge), v, (recall conventional current). Point your middle finger in the direction of the magnetic field, B. Your thumb now points in the direction of the magnetic force, F(magnetic). The right hand rule: the thumb is the direction of initial charge movement, the fingers are the direction of the field, and the palm is the direction of the acting force. magnetic force, magnetic field, and current are all perpendicular to each other 2) used to determine the direction of a magnetic field around a current-carrying wire. This wire carries an electrical current and generates a magnetic field, but how do we know which way that field rotates? Take your right hand and point your thumb in the direction of the current. Now, wrap your fingers in a half circle around the wire. Now that you've done that, the direction of your fingers indicates the direction of the magnetic field. Basically, the magnetic field rotates counterclockwise perpendicular to the direction of the current. Note that the right hand rule is for conventional current. Remember that electrons flow in the opposite direction of conventional current. If you want to determine the direction of the magnetic field based on the direction of electron flow, you will have to use your left hand instead of your right, with your thumb pointing in the direction of electron flow. ** conventional current versus electron flow: The flow of electrons is termed electron current. Electrons flow from the negative terminal to the positive. Conventional current or simply current, behaves as if positive charge carriers cause current flow. Conventional current flows from the positive terminal to the negative.

Apply knowledge of the physical and chemical properties of water.

:- Hydrogen bonding: electromagnetic attraction between polar molecules where hydrogen is bound to a larger atom; attraction between the positive and negative poles of charged atoms (dipole-dipole attraction) + Intermolecular: hydrogen bonding between two different molecules + Intramolecular: hydrogen bonding within the same molecule + Can form between atoms with a partial charge + Since water is a molecule with partially charged atoms, water can form a hydrogen bond with other water molecules - Density: measure of mass of an object per unit volume + The ordered, unbroken hydrogen bonds in ice cause water molecules to be farther apart than they would be in the liquid state. This resulting lowered density of ice relative to water explains why it floats. + Because these hydrogen bonds are all forming at the same time, the water molecules are becoming more ordered; they're forming a crystalline structure. + Because of this linkage, the water molecules are in this rigid structure, and this rigid structure is holding them farther apart than they would be if they had been in the liquid state. Because they are being held farther apart, they're occupying more volume, and because they're occupying more volume - if we remember our density formula, we said density was equal to mass divided by volume - if I've increase the volume but kept the mass the same (because we've increased this volume down here) the overall density has decreased because the denominator has increased but the numerator has stayed the same. So because this density is lower, ice is going to float on water. - States of matter and specific heat: + Water has a high specific heat: The energy that's needed to raise the temperature of one gram of a substance one degree Celsius: the specific heat + water - we also have to remember that water is linked together by hydrogen bonds. So we need to input energy into the system to break these hydrogen bonds in addition to the energy needed to change the state of matter. - Effect of water on climate and temperature: + This is the reason why bodies of water can help cool the surrounding area. So if I have my nice body of water here and I have my surrounding land, it's going to take extra energy to heat this air over here because energy is also being sucked into this water to heat this water that's close to this land. So this area that's close to the land is going to experience a more temperate climate because of this water that's insulating it from hot air, whereas somewhere farther inland, that insulation isn't happening. If water was very easy to freeze or boil, drastic changes in the environment and so in oceans or lakes would cause all the organisms living in water to die. - Why we sweat: + water has a high specific heat and we've also talked about how that impacts the amount of energy it takes to change water from a liquid to a gas. So if we have a sweat droplet sitting on top of our skin, it's going to take a lot of energy from the surrounding tissue to be able to evaporate that sweat. By removing this energy from the tissue, it has cooled you down. This is a reason why our bodies sweat: to cool down while we're exercising. - Cohesion, adhesion, and capillary action: + hydrogen bonding linking the molecules together and giving the molecules more strength. The forces that are holding the water molecules together are called cohesion. + These partial charges are the things that are interacting between the water molecules are the plastic. This is called adhesion. water molecules are polar and they can also bind to other polar things + Capillary action: It is defined as the movement of water within the spaces of a porous material due to the forces of adhesion, cohesion, and surface tension. Capillary action occurs because water is sticky, thanks to the forces of cohesion (water molecules like to stay close together) and adhesion (water molecules are attracted and stick to other substances). Adhesion of water to the walls of a vessel will cause an upward force on the liquid at the edges and result in a meniscus which turns upward. The surface tension acts to hold the surface intact. Capillary action occurs when the adhesion to the walls is stronger than the cohesive forces between the liquid molecules + Surface tension: The cohesive forces between liquid molecules are responsible for the phenomenon known as surface tension. the stronger cohesion between the water molecules as opposed to the attraction of the water molecules to the air makes it more difficult to move an object through the surface than to move it when it is completely submersed. - Water as the "Universal Solvent": + Because of water's polarity, it is able to dissolve or dissociate many particles. Oxygen has a slightly negative charge, while the two hydrogens have a slightly positive charge. The slightly negative particles of a compound will be attracted to water's hydrogen atoms, while the slightly positive particles will be attracted to water's oxygen molecule; this causes the compound to dissociate. + oxygen is the most electronegative non-noble gas element, so while forming a bond, the electrons are pulled towards the oxygen atom rather than the hydrogen. This creates 2 polar bonds, which make the water molecule more polar than the bonds in the other hydrides in the group. + A 104.5° bond angle creates a very strong dipole.

Analyze chemical bonding with respect to an element's position in the periodic table.

- As you move across a period in the periodic table, the types of commonly encountered bonding interactions change. For example, at the beginning of Period 2, elements such as lithium and beryllium form only ionic bonds, in general. Moving across the period, elements such as boron, carbon, nitrogen and oxygen tend to form covalent bonds. Fluorine can form ionic bonds with some elements, such as carbon and boron, and neon does not tend to form any bonds at all. - The left-most elements form more ionic bonds, and the further-right elements tend to form more covalent bonds. - Metals give away their valence electrons when bonding, whereas non-metals tend to take electrons. **think about the valence electrons IONIC bonds form between a metal and a nonmetal. + Ionic bonds are bonds formed between ions with opposite charges. When one atom loses an electron and another atom gains that electron, the process is called electron transfer + In an ionic bond, one atom donates an electron to another atom. This stabilizes both atoms. Because one atom essentially gains an electron and the other loses it, an ionic bond is polar. In other words, one atom in the bond has a positive charge, while the other has a negative charge. + Often, these atoms dissociate into their ions in water. + Atoms that participate in ionic bonding have different electronegativity values from each other. + Examples of compounds with ionic bonds include salt, such as table salt (NaCl). In salt, the sodium atom donates its electron, so it yields the Na+ ion in water, while the chlorine atom gains an electron and becomes the Cl- ion in water. + Metals are the elements on the left side of the Periodic Table. The most metallic elements are Cesium and Francium. Metals tend to lose electrons to attain Noble Gas electron configuration. Groups 1 and 2 (the active metals) lose 1 and 2 valence electrons, respectively, because of their low Ionization energies. COVALENT bonds form between two nonmetals. + Covalent bonds are categorized as pure or true covalent bonds and polar covalent bonds. Electrons are shared equally between atoms in pure covalent bonds, while they are shared unequally in polar covalent bonds (spend more time with one atom than the other). + These atoms can become more stable is by sharing electrons (rather than fully gaining or losing them), thus forming covalent bonds. Covalent bonds are more common than ionic bonds in the molecules of living organisms. + Atoms are bound by shared electrons in a covalent bond. In a true covalent bond, atoms have the same electronegativity values as one another. This type of covalent bond forms between identical atoms, such as hydrogen (H2) and ozone (O3). In a true covalent bond, electrical charge is evenly distributed between the atoms so the bond is nonpolar. + Covalent bonds between atoms with slightly different electronegativity values results in a polar covalent bond. However, the polarity in a polar covalent bond is less than in an ionic bond. In a polar covalent bond, the bonding electron is more attracted to one atom than to the other. The bond between hydrogen and oxygen atoms in water (H2O) is a good example of a polar covalent bond. + If the electronegativity is equal, the electrons will be shared relatively evenly to form a covalent bond + If there is a slight difference in electronegativity, the electrons will be unevenly shared, with the electrons being closer to the atom with the highest electronegativity: polar covalent bond ==> - The uneven sharing of electrons produces a permanent dipole, with one end of the bond being negative and the other positive **Dipole: A dipole is any molecule with a positive end and a negative end, resulting from unequal distribution of electron density throughout the molecule - If a molecule is symmetrical, it is NOT polar - If a molecule is asymmetrical, the molecule will be POLAR METALLIC bonds form between two metals. + Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons and positively charged metal ions. It may be described as the sharing of free electrons among a structure of positively charged ions. Metallic bonds occur among metal atoms. Whereas ionic bonds join metals to non-metals, metallic bonding joins a bulk of metal atoms - Atoms without full valence shells are reactive because they have unpaired electrons and vacant orbitals is energetically unfavorable. Vacant orbitals can be filled by either sharing electrons (covalent bonding) or by gaining or losing electrons to become an ion - The electronegativity of an atom is its ability to attract electrons. If the difference in electronegativity between two reaction atoms is very high, then the electron(s) will be entirely transferred from the atom with the lowest electronegativity to the atom with the highest electronegativity and ions will form - Non-metals are limited to the elements in the upper right hand corner of the Periodic Table. The most non-metallic element is fluorine. Non-metals tend to gain electrons to attain Noble Gas configurations. The have relatively high Electron affinities and high Ionization energies. - Metals tend to lose electrons and non-metals tend to gain electrons, so in reactions involving these two groups, there is electron transfer from the metal to the non-metal. The metal is oxidized and the non-metal is reduced. - Intermolecular forces: + Molecules interact with each other via intermolecular forces which are very weak compared to intramolecular forces that bond the atoms within molecules together + Collectively intermolecular forces are called van der Waals forces: hydrogen bonding and induced dipole-dipole forces ** Hydrogen bonds: when hydrogen forms a covalent bond with either oxygen, nitrogen, or fluorine, those atoms attract the electrons much more than the hydrogen, producing a polar covalent bond. The dipole that forms allows other similar molecules to be attracted. Hydrogen bonds are the strongest intermolecular force. ** Induced dipole-dipole forces: electrons are always in motion around an atom even when covalently bonded with other atoms; the motion is random and this results in instances where there are more electrons on one side of the molecule that another which results in a slight polarity form one side of the molecule to the other. The instantaneous dipole can affect nearby molecules, so that they also form dipoles, resulting in temporary attractions between the molecules - Covalent and ionic bonds are both typically considered strong bonds. However, other kinds of more temporary bonds can also form between atoms or molecules. Two types of weak bonds often seen in biology are hydrogen bonds and London dispersion forces. - In a polar covalent bond containing hydrogen (e.g., an O-H bond in a water molecule), the hydrogen will have a slight positive charge because the bond electrons are pulled more strongly toward the other element. Because of this slight positive charge, the hydrogen will be attracted to any neighboring negative charges. This interaction is called a hydrogen bond. - Like hydrogen bonds, London dispersion forces are weak attractions between molecules. However, unlike hydrogen bonds, they can occur between atoms or molecules of any kind, and they depend on temporary imbalances in electron distribution. - Hydrogen bonds and London dispersion forces are both examples of van der Waals forces, a general term for intermolecular interactions that do not involve covalent bonds or ions.

Evaluate evidence that indicates that certain wavelengths of electromagnetic radiation may affect living cells.

Ionizing and non-ionizing radiation: - an important aspect of EM radiation is ability to ionize atoms. recall that an ion is an atom that has lost or gained electrons, and so carries a positive or negative charge - the ability of EM radiation to ionize an atom is part of the photoelectric effect and is related to the frequency of light. the higher the frequency, the more likely it is that the EM radiation will ionize an atom - high frequency EM radiation includes UV light, x-rays, and gamma rays. these are able to knock electrons from atoms. if this occurs in body tissue, free radicals (groups of highly reactive atoms) may be produced causing tissue damage. Free radicals are atoms that contain an unpaired electron. Due to this lack of a stable number of outer shell electrons, they are in a constant search to bind with another electron to stabilize themselves—a process that can cause damage to DNA and other parts of human cells - EM radiation with longer wavelengths and therefore lower frequencies are unable to ionize atoms. these wavelengths are therefore called non-ionizing radiation biological damage: - recall that radioactive material decays by alpha, beta, or gamma radiation. when alpha or beta decay occurs, alpha and beta particles are ejected from the nucleus. these may cause tissue damage, especially if alpha and beta emitters are ingested. after particle ejection, the remaining nucleus may be in a high energy state. it reduces this energy by emitting gamma radiation - gamma radiation has much higher penetrating power than alpha or beta emissions. as a result, it can pass right through the body. as it travels through the body, the gamma ray may hit molecules of DNA, knocking electrons loose and producing ionization events. these damage the DNA by affecting the bonds between atoms or producing highly reactive free radicals. cellular repair mechanisms may repair this damage, but not always correctly. thus, mistakes in the DNA code may accumulate as more radiation is experienced and this can result in mutations and cancer - high exposure to gamma rays can damage so much cellular material it can be fatal within hours or days - light waves DON'T have enough energy to penetrate into your skin, so they don't cause any damage to your cells. - Ultraviolet light is a form of radiation that has a higher frequency than visible light. This means it also has a little bit more energy than visible light and can, therefore, penetrate into the top layers of your skin, causing damage to your cells and leading to a painful sunburn. + Although ultraviolet radiation can only penetrate into the top layers of your skin, it can still do a lot of damage. Over time, you can get skin cancer and your skin may develop deep wrinkles, making you look a lot older than you really are. - Each chromosome is made up of a long chain of DNA. + When cells are exposed to certain wavelengths of electromagnetic radiation, these DNA strands can be broken. This can cause lots of problems. If DNA is damaged, it can impair the ability of living cells to function the way they should. Changes in DNA caused by radiation can also be passed on when the cell divides, and these DNA changes can multiply and eventually cause cancer. + Damage to DNA consists of breaks in chemical bonds or other changes in the structural features of the DNA chain, leading to changes in the genetic code. In human cells, we can have as many as a million individual instances of damage to DNA per cell per day. The repair ability of DNA is vital for maintaining the integrity of the genetic code and for the normal functioning of the entire organism. A cell with a damaged ability to repair DNA, which could have been induced by ionizing radiation, can do one of the following: * The cell can go into an irreversible state of dormancy, known as senescence. * The cell can commit suicide, known as programmed cell death (apoptosis). * The cell can go into unregulated cell division, leading to tumors and cancers. - Since ionizing radiation damages the DNA, ionizing radiation has its greatest effect on cells that rapidly reproduce, including most types of cancer. Thus, cancer cells are more sensitive to radiation than normal cells and can be killed by it easily. Cancer is characterized by a malfunction of cell reproduction, and can also be caused by ionizing radiation. There is no contradiction to say that ionizing radiation can be both a cure and a cause. - Other types of radiation, like X-rays and gamma rays, can have even more profound effects. + X-rays, which have more energy than UV rays, can penetrate deeper into your body. They can pass right through soft tissues, but not through hard tissue like bone. This makes them really useful for imaging the inside of your body. Usually, short, limited exposure to X-rays does not cause much cellular damage, but if you are exposed to X-rays for a long period of time, they can cause DNA damage, too. - Gamma rays have even more energy than X-rays and are, therefore, even more dangerous. Even short exposures to gamma rays can cause significant cell damage. + In some cases, the damage to a cell's DNA from radiation can be so extensive that the cell actually dies. If this happens to a lot of cells in your body at the same time, you can get really sick and sometimes even die. When people are exposed to high levels of radiation, cells that reproduce quickly are usually most affected. This means that after exposure to radiation, you are likely to lose your hair, experience vomiting and diarrhea, and have blood cell deficiencies, which can make you anemic and/or impair your immune system. This cluster of symptoms is collectively known as radiation sickness, and it can happen following exposure to nuclear weapons or after a meltdown of a nuclear power plant. + Depending on the dose of radiation, radiation sickness is often fatal. Even if you recover, it's very likely that your cells have sustained some serious DNA damage that may cause you to develop cancer in the future. - What happens when electromagnetic radiation damages the DNA of reproductive cells? In that case, not only can the damage affect the person who was exposed, causing cell death or cancer, but even if the cell survives, the damaged DNA can be passed on to any offspring that the affected person might have. This can cause serious birth defects and other genetic problems in children.

Demonstrate knowledge of resonance and of the reflection, refraction, and transmission of waves.

It essenetially depends on the material they hit **look at document for illustrations RESONANCE: when one object vibrating at the same natural frequency of a second object forces that second object into vibrational motion - The increase in the amplitude of an oscillation of a system under the influence of a periodic force whose frequency is close to that of the system's natural frequency - Resonance is a phenomenon in which waves add up in phase (i.e., matched peaks and valleys), thus growing in amplitude. Structures have particular frequencies at which they resonate when some time-varying force acting on them transfers energy to them. This phenomenon (e.g., waves in a stretched string, vibrating air in a pipe) is used in the design of all musical instruments and in the production of sound by the human voice. REFLECTION: the change in direction of a wave when it bounces off a barrier (such as a fixed end) - When the wave hits the fixed end, it changes direction, returning to its source. As it is reflected, the wave experiences an inversion, which means that it flips vertically. If a wave hits the fixed end with a crest, it will return as a trough, and vice versa - Regardless of the angle at which the wavefronts approach the barrier, one general law of reflection holds true: the waves will always reflect in such a way that the angle at which they approach the barrier equals the angle at which they reflect off the barrier. This is known as the law of reflection - angel of incidence (I) and angle of reflection (R) - A ray of light is incident towards a plane mirror at an angle of 30-degrees with the mirror surface. What will be the angle of reflection? + The angle of reflection is 60 degrees. (Note that the angle of incidence is not 30 degrees; it is 60 degrees since the angle of incidence is measured between the incident ray and the normal.) - reflection of a sound wave off of a wall: echos (delay between original sound and echo because the sound has to travel twice as far to get back to your ears) - mirror (reflection) REFRACTION: the change in direction of a wave due to a change in its medium. - Due to change of medium (different densities of the objects), the phase velocity (speed) of the wave is changed but its frequency remains constant - Refraction of waves involves a change in the direction of waves as they pass from one medium to another. Refraction, or the bending of the path of the waves, is accompanied by a change in speed and wavelength of the waves. - Refraction of light is the most commonly observed phenomenon, but any type of wave can refract when it interacts with a medium (e.g., when sound waves pass from one medium into another or when water waves move into the water of a different depth). - Refraction is described by Snell's law: n1sinθ1 = n2sinθ2 where n1 is the incident index, n2 is the refracted index, θ1 is the incident angle, and θ2 is refracted angle - things in water look closer/shallower than they really are; straw in a glass of water looks light it bends because the refracted light wavelengths make you think the straw is in a different place than it actually is **When a wave passes an object that is small compared with its wavelength, the wave is not much affected; for this reason, some things are too small to see with visible light, which is a wave phenomenon with a limited range of wavelengths corresponding to each color. When a wave meets the surface between two different materials or conditions (e.g., air to water), part of the wave is reflected at that surface and another part continues on, but at a different speed. The change of speed of the wave when passing from one medium to another can cause the wave to change direction or refract. These wave properties are used in many applications (e.g., lenses, seismic probing of Earth). TRANSMISSION: If resonance does not occur, then what you'll get is transmission, the passing of light waves through an object. - The wave can be transmitted, which means to pass through the object. - waves keep traveling in the same direction through an object - light through a window DIFFRACTION: when waves meet a gap in a medium, they pass through the gap and then spread back out once they pass through the gap - Diffraction, the spreading of waves around obstacles. Diffraction takes place with sound; with electromagnetic radiation, such as light, X-rays, and gamma rays; and with very small moving particles such as atoms, neutrons, and electrons, which show wavelike properties. One consequence of diffraction is that sharp shadows are not produced. The phenomenon is the result of interference (i.e., when waves are superimposed, they may reinforce or cancel each other out) and is most pronounced when the wavelength of the radiation is comparable to the linear dimensions of the obstacle.

Compare the characteristics of mechanical and electromagnetic waves (e.g., transverse/longitudinal, travel through various media, relative speed).

Wave: a disturbance that travels/propagates from the place it was created - Waves transfer energy from one place to another, but they do not necessarily transfer any mass MECHANICAL WAVES: they require a medium to travel through. The energy is passed from atom to atom, molecule to molecule, through successive collisions of particles in the material - The medium can be a solid, liquid, or gas - The speed of the wave depends on the material properties of the medium though which is it traveling - i.e. sound and water waves - slower than EM waves - pulse wave: a sudden disturbance in which one wave or a few waves are generated - periodic wave: repeats the same oscillation for several cycles - simple harmonic motion: each particle in the medium experiences simple harmonic motion is periodic waves by moving back and forth periodically though the same positions - can be transverse or longitudinal: + transverse: propagates so that the disturbance is perpendicular to the direction of propagation * ripples on the surface of water; vibrations in a guitar string. + longitudinal: the disturbance is parallel to the direction of propagation * sound waves in air and water are longitudinal --> the disturbance is caused by a change in air pressure + surface: medium moves up and down and side to side; hybrid between transverse and longitudinal; ocean waves - earthquakes have both longitudinal and transverse components: + P-waves: longitudinal waves; can travel through solids, liquids, and gases. + S-waves: transverse waves; travel through solids only. + Surface waves: have and up-down and side-to-side motion; slowest ELECTROMAGNETIC WAVES: do not require a material medium to pass through. They are affected by the presence of matter which can slow the waves down as the energy is absorbed, transmitted, reflected by the particles it comes in contact with. The speed of an EM changes as it changes mediums (like mechanical waves) - Electromagnetic radiation is generated by a moving electric charge (electric current) - An electric current generates both an electric field (E) and magnetic field (B). These fields are perpendicular to each other + When the moving charge oscillates, an EM wave is propagated - Light waves can travel through a vacuum and doesn't require a medium: can travel though air, solid materials, and the vacuum of space - Transverse waves - Travel at the speed of light --> faster than mechanical waves - Electromagnetic radiation takes several forms, each of which are characterized by a range of frequencies - Because frequency is inversely proportional to wavelength, any form of EMR can also be represented by its range of wavelengths - As frequency increases across the spectrum wavelength decreases. Energy also increases with frequency so higher frequencies penetrate matter more readily + lowest frequency (greatest wavelength) to highest frequency (lowest wavelength): radio waves, microwaves, infrared, visible light (highest wavelength to lowest: red, orange, yellow, green, blue, violet), ultraviolet, x-rays, gamma rays * Subtractive color mixing: mixing pigment colors makes black; mixing two primary colors makes a secondary color * Additive color mixing: mixing light colors makes white; when all colors are added it makes white and when all colors are subtracted it makes black - Wave interference: + Constructive interference: occurs when two identical waves arrive at the same point exactly in phase; Because the disturbances add, the pure constructive interference of two waves with the same amplitude produces a wave that has twice the amplitude of the two individual waves, but has the same wavelength + Destructive interference: two identical waves exactly out of phase (aligned crest to trough); Because the disturbances are in opposite directions for this superposition, the resulting amplitude is zero for pure destructive interference; that is, the waves completely cancel out each other. * The superposition of most waves that we see in nature produces a combination of constructive and destructive interferences - Standing waves: formed by the superposition of two or more waves moving in opposite directions --> waves seem not to move and appear to just stand in place, vibrating + The waves move through each other with their disturbances adding as they go by. If the two waves have the same amplitude and wavelength, then they alternate between constructive and destructive interference. ** Nodes: the points where the string does not move --> points where the wave disturbance is zero in a standing wave ** Antinode: the location of maximum amplitude in standing waves ** Wavelength: determined by the distance between the points where the string is fixed in place

Demonstrate knowledge of the ways in which energy manifests itself at the macroscopic level (e.g., motion, sound, light, thermal energy).

mechanical energy: energy due to an object's motion or position - Mechanical motion is the physical motion of objects. This is probably the most apparent or intuitive manifestation of energy. We see it when we move our arm, when the tires of a car or bicycle spin, or when a ball falls from a cliff. When a mom tells a kid they need to go 'burn off some energy,' typically she means to go run around for a while. We think of movement as a result of energy. - Mechanical motion is often what we want to ultimately accomplish with energy. We want to move our arms, so we transfer electrons from food to our body. Heat energy may be generated in this process, but it's all to move our arms and pump our heart. - Sound energy is a form of mechanical energy that starts with a vibration in matter. For example, the singer's voice starts with vibrations of his vocal cords, which are folds of tissue in his throat. The vibrations pass to surrounding particles of matter and then from one particle to another in waves. Sound waves can travel through air, water, and other substances, but not through empty space. + The manifestation of sound energy is similar to light energy, as both move as waves. Our ears interpret waves of compressed air as sound. These sound waves occur when something vibrates (for example, a guitar string) or merely when air is compressed in some way (for example, dropping a box on the ground), which creates pressure waves. A good illustration of this is how our vocal chords vibrate to create sounds when we speak. + We could think of sound energy as motion, but the motions are on such a small scale that we can't see it occurring. But our ears are able to pick up on this motion and translate it into sound. chemical energy: stored energy released through chemical reactions - Fuels, such as gasoline and food, carry chemical energy that can be transferred to a system through oxidation. Chemical fuel can also produce electrical energy, such as in batteries. Batteries can in turn produce light, which is a very pure form of energy. electrical energy: energy from the flow of electric charge - is a common form that is converted to many other forms and does work in a wide range of practical situations - Electricity may be confusing to imagine compared to the other more evident forces. Strictly speaking, we can't see it, hear it, feel it, or touch it, although we can see its effects (for example, when a television turns on). Electric energy is the energy of an electric charge. - We see a natural manifestation of electric energy when we see lightning, although it's light energy that we see and not the electric energy itself. Another natural example of electric energy is how electron transfer (the transfer of electric charge in molecules) allows our body to get energy from food. In the past couple of centuries, we've learned how to contain and use this electric energy. This is why we're able to plug a television into an outlet in the wall and then it works. - We can look at a chemical equation and see how electrons are moving in order to follow the transfer of energy. In fact, when you see little arrows in chemical equation mechanisms, this is indicating a movement of electrons. thermal energy (heat): the internal energy of an object due to the motion of its atoms and molecules - Atoms and molecules inside all objects are in random motion. This internal mechanical energy from the random motions is called thermal energy, because it is related to the temperature of the object. - Heat is a form of energy that we can gauge by measuring a change in temperature. In chemical reactions, we often refer to heat and energy equivalently. Heat is the most common form of energy transfer in chemical equations. - When we look at the above example (the lightning storm story), heat manifested itself several times. The most obvious manifestation was the heat from the fire. But most of our energy expenditure also transfers some heat. When we ride a bike, we heat up, and the parts of the bike heat up; this is energy lost to heat. Electricity also loses some energy to heat. If we were to get too close to a lightning bolt, we would be burnt to a crisp, because there is heat energy in the lightning. - We can find evidence of energy manifesting as heat all around us. nuclear energy: the energy stored in the nucleus of an atom - Nuclear energy comes from processes that convert measurable amounts of mass into energy. Nuclear energy is transformed into the energy of sunlight, into electrical energy in power plants, and into the energy of the heat transfer and blast in weapons. radiant energy (light): energy that ravels by waves or particles, particularly electromagnetic radiation - Most energy sources on Earth are in fact stored energy from the energy we receive from the Sun. We sometimes refer to this as radiant energy, or electromagnetic radiation, which includes visible light, infrared, and ultraviolet radiation. - Light energy is energy that we can actually see. Light is technically a form of electromagnetic radiation. Typically we refer to visible light, which is electromagnetic radiation with a wavelength of 400-700 nanometers. But it could also be UV light, gamma rays, or other radiation that is not visible. These rays can be measured using special machines, but we cannot see them with our eyes. - Examples of energy manifesting itself as light in the example story are the sparkle from the fire, the lights from the television, and the light from the lightning. - In chemical reactions, sometimes light is needed in order for a reaction to occur. The light gives the energy for the reaction to occur. Photosynthesis is the most common chemical reaction that requires light, when a plant takes in light and turns it into food. - These and all other forms of energy can be converted into one another and can do work. - One pool ball hits another, transferring kinetic energy and making the second ball move (mechanical energy) - Plants convert the energy of sunlight (radiant energy) into chemical energy stored in organic molecules. You are transforming chemical energy from your last snack into kinetic energy as you walk, breathe, and move your finger to scroll up and down this page. - Importantly, none of these transfers is completely efficient. Instead, in each scenario, some of the starting energy is released as thermal energy. When it's moving from one object to another, thermal energy is called by the more familiar name of heat. It's obvious that glowing light bulbs generate heat in addition to light, but moving pool balls do too (thanks to friction), as do the inefficient chemical energy transfers of plant and animal metabolism. To see why this heat generation is important, stay tuned for the Second Law of Thermodynamics. + As it turns out, in every real-world energy transfer or transformation, some amount of energy is converted to a form that's unusable (unavailable to do work). In most cases, this unusable energy takes the form of heat. + Although heat can in fact do work under the right circumstances, it can never be turned into other (work-performing) types of energy with 100% efficiency. So, every time an energy transfer happens, some amount of useful energy will move from the useful to the useless category. + The degree of randomness or disorder in a system is called its entropy. Since we know that every energy transfer results in the conversion of some energy to an unusable form (such as heat), and since heat that does not do work goes to increase the randomness of the universe, we can state a biology-relevant version of the Second Law of Thermodynamics: every energy transfer that takes place will increase the entropy of the universe and reduce the amount of usable energy available to do work (or, in the most extreme case, leave the overall entropy unchanged). In other words, any process, such as a chemical reaction or set of connected reactions, will proceed in a direction that increases the overall entropy of the universe. + To sum up, the First Law of Thermodynamics tells us about conservation of energy among processes, while the Second Law of Thermodynamics talks about the directionality of the processes, that is, from lower to higher entropy (in the universe overall).

Identify the separate forces that act on a system (e.g., gravity, tension/compression, normal force, friction), describe the net force on the system, and describe the effect on the stability of the system.

Non-contact forces: - Gravity: a property of all masses that causes them to pull together + Acceleration of gravity (g): 9.8 m/s2 + Weight (measured in N) = mg + Free fall: a special type of motion in which gravity is the only force acting on an object + During free fall problems, we substitute g for a in acceleration equations; g= -9.8 m/s2 and the negative sign indicates the acceleration is in the downwards direction. During free fall, a point is reached at which gravitational force is equal to the opposing force of air resistance. At this point, the object stop accelerating and falls at a constant velocity. This is called terminal velocity. Surface area is very important when determining terminal velocity. The greater the surface area, the greater the air resistance, and the slower the terminal velocity + Air resistance/drag: the force opposing the downward acceleration due to gravity. It is due to contact with air particles as the object pushes through them. - Electric force: the attraction or repulsion between two charged objects - Magnetic force: force exerted between two magnetic poles; can be push or pull Contact forces: - Normal force: always perpendicular to the surface: when an object comes in contact with a surface, that surface exerts a force on the object which resists changes in the surface; a force that balances the weight on an object on a surface + It's a force of resistance: prevents the surface from deforming or breaking due to force applied through contact with an object + Always in the opposite direction of the force applied. + If the force is a pull, the direction of the normal force is away from the surface + When an object is placed on the ground, the ground exerts a normal force on the object equal to the force of gravity acting on the object (its weight) + It is exerted whenever an object comes in contact with a surface. If you were to push on a wall, the wall will exert a normal force equal to the force of your push to resist change + If the normal force is less than the applied force, the object will pass through the surface - Friction: an external force that acts opposite to the direction of motion. It's caused when materials slide past each other + The force of friction (Ft) is equal to the coefficient of friction (µ) multiplied by the normal force (FN) --> Ft = µFN - Air resistance: friction that acts on an object as it moves through the air - Tension: tension through a string or other fully-stretched object - Applied force: force applied to an object by another object - Compression/Spring: the force exerted by a compressed or stretched spring. The force required to stretch an elastic object: Fs = kx + Hooke's law: Force exerted back by the spring: Fs = -kx where x is the length of extension or compression relative to the unstretched length

Demonstrate knowledge of the definitions of power, voltage differences, current, and resistance and calculate their values in simple circuits.

Ohm's Law: V= I x R + the current is directly proportional to the voltage and inversely proportional to the resistance + increasing the voltage and inversely proportional to the resistance + increasing the voltage will cause the current to increase, while increasing the resistance will cause the current to decrease - Power: the rate at which a circuit uses electrical energy; measured in Watts: P= V * I or P = V^2/R - Resistance: a measure of how much an object impeded an electric current (the flow of electrons); measured in Ohms and affected by: + the resistivity of the material (related to the number of free electrons present) + the dimensions of an object (wire) because increasing the length of electrons have to travel will increase the resistance while increasing the cross-sectional area through which the electrons will flow will decrease the resistance + the temperature: as the temperature of the conductor increases, so will its resistance - Voltage differences: + voltage: the electrical potential energy per unit charge; electric pressure created by a power source, such as a battery + voltage drop: the loss of electrical power as a current travels through a resistor, wire or other componenet - Current: The flow of charge through an electric circuit past a given point of measurement + current flows from the negative terminal of our power supply, through the circuit, and back to the positive terminal of the power supply as it completes the loop. As current passes through resistors along the circuit there's a voltage drop (loss in voltage). The total loss of voltage around a circuit loop will equal the total voltage of the power supply. So, if you have a 12V battery powering the circuit and you have three resistors along that circuit, you'll have a total loss of 12V across the resistors. In contrast, as current flows through the power supply, it passes from the positive terminal to the negative terminal, and there's a 'voltage rise,' or increase in voltage. Again, this will be the same voltage as the power supply. + Current is inversely related to the resistance because resistance opposes electron movement through a device.

Demonstrate knowledge of the definition of pressure and how pressure relates to fluid flow and buoyancy, including describing everyday phenomena (e.g., the functioning of heart valves, atmospheric pressure).

- Pressure: force per unit area; p = F/A + Units: Pascal (N/m2), psi, atm, mmHg + Pressure only concerns the force component perpendicular to the surface upon which it acts + Pressure of an ideal gas: P = nRT/V, where n is the number of gas molecules, R is the ideal gas constant (R = 8.314 J mol-1 K-1), T is the temperature of the gas, and V is the volume of the container - the pressure exerted by the gas can be increased by: ** increasing the number of collisions of gas molecules per unit time by increasing the number of gas molecules ** increasing the KE of the gas by increasing the temperature ** decreasing the volume pf the container - Fluids: fluid is defined as any substance that flows and that takes the shape of its container (gas and liquids) + When force is exerted on a fluid, pressure pushes on the walls of the surrounding container and on all parts of the fluid itself + Pressure in liquids increase with depth due to gravity * The liquid at the bottom has to bear the weight (force due to gravity) of the liquid above it and the air above that + Hydrostatic pressure: the pressure exerted by a fluid at equilibrium at a given point within the fluid due to the force of gravity; it increases in proportion to depth measured form the surface because of the increasing weight of fluid exerting downward force above, assuming the fluid is incompressible and at rest : P = ρgh or P = ρgd, where P is fluid pressure, ρ is fluid density, g is acceleration due to gravity and h (or d) is fluid depth - Buoyant force: the upward force of a fluid + When an object is submerged in water, the pressure on the bottom of the object is greater than on the top creating a net upward force on the object, so the object is buoyed upward against gravity + Archimedes' principle: the buoyant force is equal to the weight of the fluid displaced by an object. Describes the relationship between the buoyant force and the volume and density of the displaced fluid - Buoyant force: F = ρf Vf g, where F(B) is the buoyant force, ρf is the density of the displaced fluid, Vf is the volume of the displaced fluid, and g is the acceleration due to gravity, 9.8 m/s2. It's very important to remember that the density and volume in this equation refer to the displaced fluid, NOT the object submerged in it. - This means that if the weight of the submerged object itself is equal to the buoyant force (the weight of the displaced fluid), then the object will neither sink nor float. But if the weight of the object is greater than the buoyant force (the weight of the displaced fluid), then the object will sink. And, if the weight of the object is less than the buoyant force (still the weight of the displaced fluid!) then it will rise to the surface and float. - Fish don't float or sink because their weight is equal to the buoyant force. But a heavy boulder sinks to the bottom of a lake because its weight is more than that of the fluid it displaces. And a piece of wood floats on the surface because its weight is much less than that of the fluid it displaces. - Principle of flotation: a floating object will displace a weight of fluid equal to the weight of the object - This also means that the buoyant force will be greater on objects in denser fluids than fluids that are less dense. You are more likely to float in salt water than freshwater because saltwater is denser than freshwater. But the reverse is also true: less dense objects float more easily than denser ones. - If you take an entire iron ship and melt it into a solid block, it will take up less volume because it fills a smaller area. But this also means it displaces a smaller volume of water, which in turn decreases the buoyant force. A block of iron will sink, but an iron ship will float because its wide bottom takes up more space in the water, displacing more water and weight, and therefore increasing the buoyant force pushing upward against it. - Pascal's principle: used to quantitatively relate the pressure at two points in an incompressible, static fluid. It states that pressure is transmitted, undiminished, in an enclosed static fluid + The total pressure at any point within an incompressible, static fluid is equal to the sum of the applied pressure at any point in that fluid and the hydrostatic pressure change due to a difference in height within that fluid + Through the application of Pascal's principle, a static liquid can be utilized to generate a large output force using smaller input force, yielding important devices such as hydraulic presses + Δp=ρgΔh + A hydraulic jack can lift a 2-ton vehicle by simply pushing on the jack's handle. This works because the pressure the mechanic exerts on the handle is transmitted without diminishing to all parts of the fluid-filled jacking system. In other words, a small force applied to a small area can generate the larger force at a large area - Atmospheric pressure: a measure of absolute pressure and is due to the weight of the air molecules above a certain height relative to sea level, increasing with decreasing altitude and decreasing with increasing altitude + Atmospheric pressure is the magnitude of pressure in a system due to the atmosphere, such as the pressure exerted by air molecules (a static fluid) on the surface of the earth at a given elevation. + Depending on the altitude relative to sea level, the actual atmospheric pressure will be less at higher altitudes (less weight of air molecules on top of it) and more at lower altitudes as the weight of air molecules in the immediate atmosphere changes, thus changing the effective atmospheric pressure. + Atmospheric pressure is a measure of absolute pressure and can be affected by the temperature and air composition of the atmosphere - Bernoulli's principle: the idea that where the speed of a fluid increases, the pressure in the fluid decreases. A fluid's speed will increase as it travels through narrower spaces and decrease as it travels through wider spaces. The increase or decrease in speed is caused by a pressure change within the fluid. + Airplane wings provide a great example of this principle in action. Airplane wings are designed so that air will flow faster over the top of the wing than underneath it (less pressure). The top of the wing has a greater curve than the bottom, and this curve crowds the streamlines together. Since the streamlines are closer together, there is less pressure in the fluid (the air) above the wing than below it. Since the pressure below the wing is greater, it creates an upward lift toward the area of lower pressure, pushing upward on the bottom of the wing. - Venturi Effect: when fluid is constricted, it decreases in pressure but increases in velocity + Bloodstreams: Your blood travels through blood vessels in a specific way, moving from the heart through arteries then capillaries then veins back to the heart. Now, major veins and arteries are substantially larger than capillaries, which are actually pretty tiny. So, for blood to move from arteries to veins, it has to pass through the constricting capillaries. And there it is, the Venturi effect in action. In order for the overall blood pressure to remain constant, blood must flow faster but at lower pressure through these smaller veins. + Ex: an artery that is being clogged by cholesterol. The cholesterol (lipid) build up creates a constriction, one that the artery is not naturally designed to handle. So, as blood passes through the constriction, it speeds up and loses pressure. To compensate, the blood pressure on either side has to be higher, and the heart has to pump harder to maintain total pressure. Also, if this section of the artery gets too clogged, and the pressure decreases too much, the blood vessel won't be able to sustain its own weight and could collapse in on itself. + Pressure in the body: Pressure, along with the potential for work arising from differences in pressure, plays an essential role in the functionality of the circulatory and respiratory systems - The circulatory system: Relies on pressure differences for circulating blood, along with oxygen, necessary nutrients, and waste products throughout the body + Circulatory system: a closed fluid system under pressure + Blood can be regarded as a viscous liquid contained within the circulatory system that travels throughout this closed system as a result of pressure and pressure differences within the circulatory system + As the volume of blood in the system is confined to veins, arteries, and capillaries, there is a pressure within this closed system + Pressure differences arise because of the varying diameters of these vessels and as the valves and heart continuously pump the blood + These pressure differences result in the potential for blood to circulate throughout the system + Blood pressure varies throughout the body and depends on heart rate, blood volume, blood viscosity, and resistance of the circulatory system (veins, arteries, capillaries) - The respiratory system: + Respiration is made possible as a result of pressure differences between the thoracic cavity, the lungs, and the environment and is largely regulated by movement of the diaphragm + Pressure difference between the lungs and the atmosphere create a potential for air to enter the lungs, resulting in inhalation + Inhalation is due to lowering of the diaphragm which increases the volume of the thoracic cavity (A hollow place or space, or a potential space, within the body or one of its organs) surrounding the lungs, thus lowering its pressure (ideal gas law: as V increase, P decreases). This reduction in pressure of the cavity keeps lungs inflated, pulls airs into the lungs, inflating the alveoli (Small air sacs or cavities in the lung that give the tissue a honeycomb appearance and expand its surface area for the exchange of oxygen and carbon dioxide) and resulting in oxygen transport needed for respiration + As diaphragm restores and moves upwards, pressure within the cavity increases, resulting in exhalation

Demonstrate knowledge of nuclear forces that hold nuclei together and are responsible for nuclear processes (e.g., fission, fusion) and radioactivity (e.g., alpha, beta, and gamma decay).

- a nuclear reaction that changes the nucleus of an atom: the number of protons and/or neutrons is changed as a result of a nuclear reaction; nuclear reactions RELEASE energy + Albert Einstein's E = mc2 equation relates mass and energy: any reaction produces or consumes energy due to a loss or gain in mass. A small change in mass results in a large change in energy + nuclear binding energy: the amount of energy needed to break one mole of nuclei into individual nucleons. The larger the binding energy per nucleon, the stronger the nucleons are held together, the more stable the nucleus is and the harder it is to break it apart. * light nuclei gain stability by undergoing nuclear fusion. Heavy nuclei gain stability by undergoing nuclear fission. Mass number 60 is most stable, so atoms with mass number greater than 60 tend to fragment into smaller atoms to increase their stability - 2 types of nuclear reactions: FISSION and FUSION + nuclear fission: large nuclei are split into smaller fragments, and neutrons and energy are released; a type of radioactive decay. The total mass is reduced and the "lost" mass appears as an equivalent release of energy * nuclear power plants use nuclear fission to generate power. The nuclei of uranium atoms can undergo nuclear fission naturally. Nuclear power plants use U-235 nucleus to undergo fission by hitting them with neutrons. Ba-141 and Kyrpton-92 are just some of the isotopes that can come from the fission of a U-235 nuclear. Nuclear power plants used controlled chain reactions to generate electrical energy; uses rods to keep chain reaction going and under control * nuclear chain reaction: a continuous series of nuclear fission reactions, a self-sustaining process in which one reaction initiates the next. The number of fissions and the amount of energy released can increase rapidly and if uncontrolled, huge amounts of energy are released very quickly (atom bomb) + nuclear fusion: small nuclei are put together to make a bigger one. Hydrogen bomb * occurs in stars; in our sun, proton-proton fusion is occurring. Nuclear fusion in stars occurs due to extremely high pressure and temperature in their cores. The gas in the core is heated to the point of being a plasma (electrons can leave their associated atoms, creating a gas filled with positive ions and free electrons). Pressure is needed to bring the atoms close enough together to fuse (protons repel each other because of like positive charge). High temperature is needed to overcome the coulomb force (given off by objects due to electric charge) between the atomic nuclei. More massive stars have higher pressure and temperature inside it because its own gravity pushes inwards on it. As the stars grow older, there will be less atoms until it can no longer support large scale fusion of them. Stars collapse when inwards force (star's gravity) is greater than the lesser outwards force by lowering fusion. Proton-proton fusion: hydrogen atoms are fused together through several steps to form Helium-4 atom, releasing a lot of energy in the process. It only requires little mass to create a lot of energy according to the E = mc2 equation * nuclear fusion power plants are hard to make because of their high pressure and temperature requirements * The weak force plays an important role in nuclear fusion, the reaction that powers the sun and thermonuclear (hydrogen) bombs. The first step in hydrogen fusion is to smash two protons together with enough energy to overcome the mutual repulsion they experience due to the electromagnetic force. If the two particles can be brought close enough to each other, the strong force can bind them together. This creates an unstable form of helium (2He), which has a nucleus with two protons, as opposed to the stable form of helium (4He), which has two protons and two neutrons. The next step is where the weak force comes into play. Because of the overabundance of protons, one of the pair undergoes beta decay. After that, other subsequent reactions, including the intermediate formation and fusion of 3He, eventually form stable 4He. RADIOACTIVITY: strong nuclear force stabilizes the nucleus by offsetting the electrostatic repulsion between protons, but in UNSTABLE elements, the protons and neutrons do not stay together indefinitely. The nucleus of the atoms in these elements decay into different atoms by emitting particles. - Each isotope decays at a specific rate and this can be used to date rocks, fossils, mineral-based objects - ALPHA decay: radioactive element splits to form an alpha particle (He nucleus: two protons, two neutrons, no electrons) and a new element + Results in change in atom's atomic mass because two protons and two neutrons are ejected from an atom as an alpha particle/He nucleus + Alpha particles are relatively heavy and quite slow-moving; can be blocked by air, paper, clothing, skin; dangerous if ingested - BETA decay: radioactive element splits to form a beta particle (an electron or positron) and form a new element or isotope + Includes the emission of an electron (negative beta decay) OR a positron (positive beta decay) + When an electron is emitted, the mass number stays the same. A neutron is converted into a proton, raising the atomic number by one + When a positron is emitted, the mass number stays the same. A proton is converted into a neutron, lowering the atomic number by one) + Often occurs when the nucleus contains too many neutrons + Beta particles are (basically a high-energy electron being emitted from the nucleus) high-energy and very light; can travel through paper and some clothing but usually stopped by first few layers of skin; need aluminum sheet to shield beta particles; can cause tissue damage (damages healthy cells --> causes cancer but also can damage cancer cells --> cure for cancer) - GAMMA decay: does NOT change the mass or atomic number of the isotope but it does REMOVE energy, producing a slightly more stable atom. Normally occurs after alpha or beta decay + An excited nucleus emits gamma rays, but its proton (atomic number) and neutron count stay the same + When protons and neutrons fall to lower energy levels releasing radiation --> very high energy gamma rays + Requires thick lead to block radiation/gamma rays; very dangerous and can cause internal damage because they can pass through the body; internal cell death; can be used in treatment of certain cancers * Law of conservation of nucleon number: the total number of nucleons (protons and neutrons) does not change in a nuclear reaction * The charged weak nuclear interaction causes flavour change. For example, a neutron is heavier than a proton (its partner nucleon), and can decay into a proton by changing the flavour (type) of one of its two down quarks to an up quark. Neither the strong interaction nor electromagnetism permit flavour-changing, so this proceeds by weak decay Phenomena involving nuclei are important to understand, as they explain the formation and abundance of the elements, radioactivity, the release of energy from the sun and other stars, and the generation of nuclear power. To explain and predict nuclear processes, two additional types of interactions—known as strong and weak nuclear interactions—must be introduced. They play a fundamental role in nuclei, although not at larger scales because their effects are very short range. The strong nuclear interaction provides the primary force that holds nuclei together and determines nuclear binding energies. Without it, the electromagnetic forces between protons would make all nuclei other than hydrogen unstable. Nuclear processes mediated by these interactions include fusion, fission, and the radioactive decays of unstable nuclei. These processes involve changes in nuclear Page 112 Suggested Citation:"5 Dimension 3: Disciplinary Core Ideas - Physical Sciences." National Research Council. 2012. A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. Washington, DC: The National Academies Press. doi: 10.17226/13165.× binding energies and masses (as described by E = mc2), and typically they release much more energy per atom involved than do chemical processes. Nuclear fusion is a process in which a collision of two small nuclei eventually results in the formation of a single more massive nucleus with greater net binding energy and hence a release of energy. It occurs only under conditions of extremely high temperature and pressure. Nuclear fusion occurring in the cores of stars provides the energy released (as light) from those stars. The Big Bang produced matter in the form of hydrogen and smaller amounts of helium and lithium. Over time, stars (including supernova explosions) have produced and dispersed all the more massive atoms, starting from primordial low-mass elements, chiefly hydrogen. Nuclear fission is a process in which a massive nucleus splits into two or more smaller nuclei, which fly apart at high energy. The produced nuclei are often not stable and undergo subsequent radioactive decays. A common fission fragment is an alpha particle, which is just another name for a helium nucleus, given before this type of "radiation" was identified. In addition to alpha particles, other types of radioactive decays produce other forms of radiation, originally labeled as "beta" and "gamma" particles and now recognized as electrons or positrons, and photons (i.e., high-frequency electromagnetic radiation), respectively. Because of the high-energy release in nuclear transitions, the emitted radiation (whether it be alpha, beta, or gamma type) can ionize atoms and may thereby cause damage to biological tissue. Nuclear fission and radioactive decays limit the set of stable isotopes of elements and the size of the largest stable nucleus. Spontaneous radioactive decays follow a characteristic exponential decay law, with a specific lifetime (time scale) for each such process; the lifetimes of different nuclear decay processes range from fractions of a second to thousands of years. Some unstable but long-lived isotopes are present in rocks and minerals. Knowledge of their nuclear lifetimes allows radiometric dating to be used to determine the ages of rocks and other materials from the isotope ratios present. In fission, fusion, and beta decay processes, atoms change type, but the total number of protons plus neutrons is conserved. Beta processes involve an additional type of interaction (the weak interaction) that can change neutrons into protons or vice versa, along with the emission or absorption of electrons or positrons and of neutrinos. Isolated neutrons decay by this process.

Relate electric currents to magnetic fields and describe the application of these relationships, such as in electromagnets, electric current generators, motors, and transformers.

- electric current produces a magnetic field - faraday's law: a magnetic field produces an electric current, as long as the magnetic field is changing + the process of generating electric current with a changing magnetic field is called electromagnetic induction (when a voltage is induced by a changing magnetic field). It occurs whenever a magnetic field and an electric conductor, such as a coil of wire, move relative to one another. As long as the conductor is part of a closed circuit, current will flow through it whenever it crosses magnetic field lines. One way this can happen is pictured in Figure below. It shows a magnet moving inside a wire coil. Another way is for the coil to move instead of the magnet. + With electromagnetic induction, an electric current can be produced in a coil of wire by moving a magnet in or out of that coil, or by moving the coil through the magnetic field. Either way, voltage is created through motion. + The amount of voltage induced depends on the number of loops in the coil of wire, as well as the speed at which the magnet is moved through the coil. A greater number of coils means a greater amount of voltage is induced. Similarly, the faster the magnet is moved through the coil, the more voltage you get. The magnetic field in space around an electric current is proportional to the electric current which serves as its source, just as the electric field in space is proportional to the charge which serves as its source. Ampere's Law states that for any closed loop path, the sum of the length elements times the magnetic field in the direction of the length element is equal to the permeability times the electric current enclosed in the loop. - Ampere's law used to quantify magnetic field of an infinitely long straight wire: B = μI/(2πr) where B is the magnetic field (Tesla), I is current (amperes), r is radial distance (m) - alternating current (AC) alternates direction as it flows, while direct current (DC) does not change direction as it moves through a circuit + Alternating current, abbreviated AC, pushes the electrons back and forth, changing the direction of the flow several times per second + In a direct current, the electrons flow in one direction. Batteries create a direct current because the electrons always flow from the 'negative' side to the 'positive' side. - ELECTROMAGNETS employ electric currents to make magnetic fields, often aided by induced fields in ferromagnetic materials + An electromagnet is a magnet that relies on an electric current to produce the magnetic field. The simplest electromagnet is simply a wire carrying a current, which generates a magnetic field all around the wire. By wrapping the wire into a coil, the magnetic field becomes stronger in the center of the coil. The addition of a ferromagnetic core in the center of the coil dramatically increases the strength of the magnetic field. + An electromagnet is a magnet that uses an electric current to generate its magnetic field. This differs from permanent magnets, like the ones on your refrigerator, which rely on the magnetic properties of the atoms in the material to create a magnetic field. At this point, our electromagnet is just a wire, but the magnetic field is too weak to do anything practical. However, if we bend the wire around and around to form a coil, the magnetic fields of the loops will concentrate in the center. To further enhance this effect, we can wrap multiple layers of wire on top of each other. Using more turns of wire increases the strength of the magnetic field. This is a definite improvement over our single wire from before, but it's still not strong enough to be really practical. + We can make our electromagnet several thousand times stronger by putting a core of ferromagnetic material, such as iron, in the center of the coil. Ferromagnetic materials contain something called magnetic domains, which are areas in the material that act like tiny magnets. Normally, the domains are randomly configured and the material does not exhibit any magnetism. However, when exposed to a magnetic field, like the one created by our coil of wire, the domains start to align and the individual magnetic fields unify into a bigger field. + The degree of domain alignment depends on the strength of the magnetic field generated by the coil, which as we learned earlier can be controlled by the amount of current flowing through the wire. Just as importantly, when the current is turned off, the magnetic domains go back to their random configuration and the electromagnet loses nearly all of its magnetism. The ability to control a very powerful magnet with a switch has many practical applications. - electric GENERATORS: depends on electromagnetic induction; A generator converts mechanical energy into electrical energy + a device that changes kinetic energy to electrical energy through electromagnetic induction + a generator produces electricity by rotating a coil in a stationary magnetic field + In a generator, some form of energy is applied to turn a shaft. This causes a coil of wire to rotate between opposite poles of a magnet. Because the coil is rotating in a magnetic field, electric current is generated in the wire. If the diagram in Figure below looks familiar to you, that's because a generator is an electric motor in reverse. Look back at the electric motor in Figure above. If you were to mechanically turn the shaft of the motor (instead of using electromagnetism to turn it), the motor would generate electricity just like an electric generator. + Generators may be set up to produce either alternating or direct current. Generators in cars and most power plants produce alternating current. + A car generator produces electricity with some of the kinetic energy of the turning crankshaft. The electricity is used to run the car's lights, power windows, radio, and other electric devices. Some of the electricity is stored in the car's battery to provide electrical energy when the car isn't running. + A power plant generator produces electricity with the kinetic energy of a turning turbine. The energy to turn the turbine may come from burning fuel, falling water, or some other energy source. + can be either AC or DC + The shaft of an electric generator is connected to the rotor which is driven by a mechanical force. + In a generator, current is produced in the armature winding. + In power stations, generator is used to generate electricity. - electric MOTORS: a motor does the opposite of a generator - it converts electrical energy into mechanical energy + in a motor, a current is passed through a coil, which forces it to spin + can be either AC or DC + electricity flows inward for a motor and outward for a generator + The working principle of a motor is based on the current-carrying conductor that experiences a force when it is kept in the magnetic field. + The shaft of an electric motor is driven by a magnetic force which is developed between the armature and field. + In a motor, current is supplied to the armature winding. + Ceiling fans, cars, etc. are all examples of motor. + Electric generators induce an emf by rotating a coil in a magnetic field, + When the coil of a motor is turned, magnetic flux changes, and an emf (consistent with Faraday's law of induction) is induced. The motor thus acts as a generator whenever its coil rotates. This will happen whether the shaft is turned by an external input, like a belt drive, or by the action of the motor itself. That is, when a motor is doing work and its shaft is turning, an emf is generated + An emf (electromagnetic field) is induced in the coil when a bar magnet is pushed in and out of it. - electric TRANSFORMERS: depends on electromagnetic induction + An electric transformer is a device that uses electromagnetic induction to change the voltage of electric current. A transformer may either increase or decrease voltage, but it only works with alternating current (AC). + An electric transformer connects two circuits with an iron core that becomes an electromagnet. + a transformer consists of two wire coils wrapped around an iron core. When alternating primary current passes through coil P, it magnetizes the iron core. Because the current is alternating, the magnetic field of the iron core keeps reversing. This changing magnetic field induces alternating current in coil S, which is part of another circuit. In Figure above, coil P and coil S have the same number of turns of wire. In this case, the voltages of the primary and secondary currents are the same. However, when the two coils have different numbers of turns, the voltage of the secondary current is different than the voltage of the primary current ** When coil S has more turns of wire than coil P, the voltage in the secondary current is greater than the voltage in the primary current. This type of transformer is called a step-up transformer. ** When coil S has fewer turns of wire than coil P, the voltage in the secondary current is less than the voltage in the primary current. This type of transformer is called a step-down transformer.

Predict charges or poles on the basis of attraction/repulsion observations.

- there are two types of magnetic poles: north magnetic pole and south magnetic pole. + north magnetic poles are those that are attracted toward the Earth's geographic north pole + like poles repel and unlike poles attract + magnetic poles always occur in pairs of north and south; it is not possible to isolate north and south poles + all magnetism is created by electric current + ferromagnetic materials, such as iron, are those that exhibit strong magnetic effects. the atoms in ferromagnetic materials act like small magnets (due to currents within the atoms) and can be aligned. These materials are strongly attracted to magnets. Here are some characteristics of a magnetic field: - The lines of flux travel through the magnet - They leave the magnet at the north pole. - They travel through the air in a curve. - The lines enter the magnet at the south pole. - A line tangent to any point on a line of flux shows the direction of the field - which is the direction of the force that would be exerted on a north pole. - Where the lines are close together the field is the strongest. - The direction of the field is NORTH to SOUTH. The arrows point away from the north pole and towards the south pole.

Demonstrate knowledge of electrostatic and magnetostatic phenomena, including evaluating examples of each type of phenomenon.

ELECTROSTATICS: electric charges at rest - basic characteristics of static electricity: + The effects of static electricity are explained by a physical quantity, called electric charge (unit: coulomb) + There are only two types of charge, one called positive and the other called negative. + Like charges repel, whereas unlike charges attract. + The force between charges decreases with distance. + Every atom is made of negatively-charged electrons surrounding a positively-charged nucleus. The nucleus contains protons, which are positively charged, and neutrons, which are neutral (they have no net electric charge). Electrons can move from one atom, molecule or material, to another. Most objects do not have an electric charge because there is a balance of electrons and protons in the material that makes up the object. In certain circumstances, there can be an imbalance of protons and electrons. An object with a greater number of electrons than protons is negatively charged. An object with more protons than electrons is positively charged. + Charging by Friction: When two materials are rubbed together, some electrons may be transferred from one material to the other, leaving them both with a net electric charge. The material that lost electrons becomes positively charged, while the material that gained electrons becomes negatively charged. Both insulators and conductors can gain a net charge in this way. This is how clothing gets charged in the clothes dryer, or our bodies get charged when we walk across a carpeted floor. - separation of charge in atoms: Charges in atoms and molecules can be separated—for example, by rubbing materials together. + Some atoms and molecules have a greater affinity for electrons than others and will become negatively charged by close contact in rubbing, leaving the other material positively charged. + Positive charge can similarly be induced by rubbing. + Methods other than rubbing can also separate charges. Batteries, for example, use combinations of substances that interact in such a way as to separate charges. Chemical interactions may transfer negative charge from one substance to the other, making one battery terminal negative and leaving the first one positive. + No charge is actually created or destroyed when charges are separated as we have been discussing. Rather, existing charges are moved about. In fact, in all situations the total amount of charge is always constant. This universally obeyed law of nature is called the law of conservation of charge. + CONDUCTORS: A conductor is a substance that allows charge to flow freely through its atomic structure. Some substances, such as metals and salty water, allow charges to move through them with relative ease. Some of the electrons in metals and similar conductors are not bound to individual atoms or sites in the material. These free electrons can move through the material much as air moves through loose sand. Any substance that has free electrons and allows charge to move relatively freely through it is called a conductor. The moving electrons may collide with fixed atoms and molecules, losing some energy, but they can move in a conductor. Superconductors allow the movement of charge without any loss of energy. Salty water and other similar conducting materials contain free ions that can move through them. An ion is an atom or molecule having a positive or negative (nonzero) total charge. In other words, the total number of electrons is not equal to the total number of protons. + INSULATORS: An insulator holds charge within its atomic structure. for example, glass does not allow charges to move through them. These are called insulators. Electrons and ions in insulators are bound in the structure and cannot move easily as in conductors. Pure water and dry table salt are insulators, for example, whereas molten salt and salty water are conductors. - Charging by Contact: + an electroscope being charged by touching it with a positively charged glass rod. Because the glass rod is an insulator, it must actually touch the electroscope to transfer charge to or from it. (Note that the extra positive charges reside on the surface of the glass rod as a result of rubbing it with silk before starting the experiment.) Since only electrons move in metals, we see that they are attracted to the top of the electroscope. There, some are transferred to the positive rod by touch, leaving the electroscope with a net positive charge. ** An electroscope is typically made with gold foil leaves hung from a (conducting) metal stem and is insulated from the room air in a glass-walled container. A positively charged glass rod is brought near the tip of the electroscope, attracting electrons to the top and leaving a net positive charge on the leaves. Like charges in the light flexible gold leaves repel, separating them. When the rod is touched against the ball, electrons are attracted and transferred (because of the rods net positive charge), reducing the net charge on the glass rod but leaving the electroscope positively charged. The excess charges are evenly distributed in the stem and leaves of the electroscope once the glass rod is removed. ** Electrostatic repulsion in the leaves of the charged electroscope separates them. The electrostatic force has a horizontal component that results in the leaves moving apart as well as a vertical component that is balanced by the gravitational force. Similarly, the electroscope can be negatively charged by contact with a negatively charged object. - Charging by Induction: + It is not necessary to transfer excess charge directly to an object in order to charge it. Figure 18.13 shows a method of induction wherein a charge is created in a nearby object, without direct contact. Here we see two neutral metal spheres in contact with one another but insulated from the rest of the world. A positively charged rod is brought near one of them, attracting negative charge to that side, leaving the other sphere positively charged. + This is an example of induced polarization of neutral objects. Polarization is the separation of charges in an object that remains neutral. If the spheres are now separated (before the rod is pulled away), each sphere will have a net charge. Note that the object closest to the charged rod receives an opposite charge when charged by induction. Note also that no charge is removed from the charged rod, so that this process can be repeated without depleting the supply of excess charge. + Charging by induction. (a) Two uncharged or neutral metal spheres are in contact with each other but insulated from the rest of the world. (b) A positively charged glass rod is brought near the sphere on the left, attracting negative charge and leaving the other sphere positively charged. (c) The spheres are separated before the rod is removed, thus separating negative and positive charge. (d) The spheres retain net charges after the inducing rod is removed—without ever having been touched by a charged object. - Another method of charging by induction: A neutral metal sphere is polarized when a charged rod is brought near it. The sphere is then grounded, meaning that a conducting wire is run from the sphere to the ground. Since the earth is large and most ground is a good conductor, it can supply or accept excess charge easily. In this case, electrons are attracted to the sphere through a wire called the ground wire, because it supplies a conducting path to the ground. The ground connection is broken before the charged rod is removed, leaving the sphere with an excess charge opposite to that of the rod. Again, an opposite charge is achieved when charging by induction and the charged rod loses none of its excess charge. - neutral objects: Neutral objects can be attracted to any charged object. When a charged rod is brought near a neutral substance, an insulator in this case, the distribution of charge in atoms and molecules is shifted slightly. Opposite charge is attracted nearer the external charged rod, while like charge is repelled. Since the electrostatic force decreases with distance, the repulsion of like charges is weaker than the attraction of unlike charges, and so there is a net attraction. Thus a positively charged glass rod attracts neutral pieces of paper, as will a negatively charged rubber rod. Some molecules, like water, are polar molecules. Polar molecules have a natural or inherent separation of charge, although they are neutral overall. Polar molecules are particularly affected by other charged objects and show greater polarization effects than molecules with naturally uniform charge distributions. + Figure 18.15 Both positive and negative objects attract a neutral object by polarizing its molecules. (a) A positive object brought near a neutral insulator polarizes its molecules. There is a slight shift in the distribution of the electrons orbiting the molecule, with unlike charges being brought nearer and like charges moved away. Since the electrostatic force decreases with distance, there is a net attraction. (b) A negative object produces the opposite polarization, but again attracts the neutral object. (c) The same effect occurs for a conductor; since the unlike charges are closer, there is a net attraction. - grounding: A conducting object is said to be grounded if it is connected to the Earth through a conductor. Grounding allows transfer of charge to and from the earth's large reservoir. - examples: Many of the characteristics of static electricity can be explored by rubbing things together. + Rubbing creates the spark you get from walking across a wool carpet, for example. + Static cling generated in a clothes dryer and the attraction of straw to recently polished amber also result from rubbing. + Similarly, lightning results from air movements under certain weather conditions. + You can also rub a balloon on your hair, and the static electricity created can then make the balloon cling to a wall. Electrons move from your hair to the balloon, causing each of the hairs to have the same positive charge. Since objects with the same charge repel each other, the hairs try to get as far from each other as possible. The farthest they can get is by standing up and away from the others. + We also have to be cautious of static electricity, especially in dry climates. When we pump gasoline, we are warned to discharge ourselves (after sliding across the seat) on a metal surface before grabbing the gas nozzle. + Attendants in hospital operating rooms must wear booties with a conductive strip of aluminum foil on the bottoms to avoid creating sparks which may ignite flammable anesthesia gases combined with the oxygen being used. + When a person touches a Van de Graaff generator, some electrons are attracted to the generator, resulting in an excess of positive charge, causing her hair to stand on end. A Van de Graaff generator produces a static electric charge by rubbing two materials together (for example, a rubber belt and felt or metal). This is the same concept as shoes on a carpet, but the charge produced can be much greater. See what happens when you place your hand on the dome before it is turned on, and you are standing on a rubber pad. The rubber pad provides insulation so that the charge from the generator does not travel through your body into the ground. When the Van de Graaff generator starts charging, it transfers the charge to the person who is touching it. Since the person's hair follicles are getting charged to the same potential, they try to repel each other. This is why the hair actually stands up. - energy storage in electrostatics (static charges) = capacitance - Stationary charges produce electrostatic fields - Coulombs law: F = K (q1q2/r^2) where F is the electric force directed on a line between the two charged bodies, K is a constant, q0 and q1 represent the amount of charge on each body in coulombs, r is the distance of separation between the charged bodes MAGNETOSTATICS: magnetic fields in systems where the currents are steady. - Magnetism is the ability of a material to be attracted by a magnet and to act as a magnet. Magnetism is due to the movement of electrons within atoms of matter. When electrons spin around the nucleus of an atom, it causes the atom to become a tiny magnet, with north and south poles and a magnetic field. In most materials, the north and south poles of atoms point in all different directions, so overall the material is not magnetic. Examples of nonmagnetic materials include wood, glass, plastic, paper, copper, and aluminum. These materials are not attracted to magnets and cannot become magnets. In other materials, there are regions where the north and south poles of atoms are all lined up in the same direction. These regions are called magnetic domains. Generally, the magnetic domains point in different directions, so the material is still not magnetic. However, the material can be magnetized (made into a magnet) by placing it in a magnetic field. When this happens, all the magnetic domains line up, and the material becomes a magnet. You can see this in the Figure below. Materials that can be magnetized are called ferromagnetic materials. They include iron, cobalt, and nickel. - Magnetic domains must be lined up by an outside magnetic field for most ferromagnetic materials to become magnets. - Temporary and Permanent Magnets: Materials that have been magnetized may become temporary or permanent magnets. - magnetostatic fields are produced by steady (DC) currents or permanent magnets. - Electric current produces a magnetic field. This magnetic field can be visualized as a pattern of circular field lines surrounding a wire. One way to explore the direction of a magnetic field is with a compass, as shown by a long straight current-carrying wire in. Another version of the right hand rule emerges from this exploration and is valid for any current segment—point the thumb in the direction of the current, and the fingers curl in the direction of the magnetic field loops created by it. - Magnetostatics is the theory of the magnetic field in conditions in which its behavior is independent of electric fields, including: + The magnetic field associated with various spatial distributions of steady current + The energy associated with the magnetic field + Inductance, which is the ability of a structure to store energy in a magnetic field - energy storage in magnetostatics (steady current, magnetized material) = inductance - Steady currents produce magnetic fields that are constant in time; hence the term magnetostatics is used. By steady current we mean a flow of charge which has been going on forever, never increasing, never decreasing - Permanent magnets are objects made from ferromagnetic material that produce a persistent magnetic field. + Permanent magnets are objects made from magnetized material and produce continual magnetic fields. Everyday examples include refrigerator magnets used to hold notes on a refrigerator door. + Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic. Examples of these materials include iron, nickel, and cobalt. The counterexample to a permanent magnet is an electromagnet, which only becomes magnetized when an electric current flows through it. + Magnets always have a north pole and a south pole, so if one were to split a permanent magnet in half, two smaller magnets would be created, each with a north pole and south pole. + Permanent magnets are made from ferromagnetic materials that are exposed to a strong external magnetic field and heated to align their internal microcrystalline structure, making them very hard to demagnetize. + magnetic field lines in a magnet point away from the north pole of the magnet, toward the south pole of the magnet