Chemistry 141 - MSU
Endothermic Reaction
A chemical reaction in which energy is absorbed
Exothermic Reaction
A chemical reaction that releases energy, usually in the form of heat.
products
A chemical substance formed as a result of a chemical reaction By convention, we represent a reaction by writing a "chemical equation" whereby reactants are transformed into products, R--->P
reactants
A chemical substance that is present at the start of a chemical reaction
Distinguish between the 3 states of matter: solid, liquid, gas
Gases, liquids and solids are all made up of atoms, molecules and ions. 1) Liquid - they are packed close together like solids, but have a weaker attraction allowing them to move. Liquids have a fixed volume, but not a fixed shape, and take the shape of their container. Ex: water alcohol, and gasoline are liquids at room temp. 2) Solid - They are packed close to each other in a fixed location due to their strong attraction to one another. A solid has a fixed volume and a rigid shape. 3) Gas - he attraction between particles is very weak allowing them to move freely and at a large distance before colliding with one another. Due to the large amount of space between the particles, gases are compressible. Gases always assume the shape and volume of their container. Ex: helium, nitrogen, and carbon dioxide at room temp.
Most nonmetal atoms prefer to be surrounded by
eight valence electrons
Examples of Potential Energy
elastic, gravitational, chemical
Water has unique properties compared with
similar molecules based on size, constituent atoms, and molar mass.
identify the cubic crystalline lattice types
simple, body-centered and face centered
hybridization. for expanded octets
sp3d and sp3d2
sublimation
the phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first (ex. dry ice)
Metals and Non-metals
we can divide the periodic table into three types of elements •metals •have a tendency to lose electrons - cations •non-metals •have a tendency to gain electrons - anions •semi-metals (metalloids) - don't generally gain or lose electrons or form ions
deposition
when a gas or vapor changes directly into a solid without first changing to a liquid (ex. frost)
speed of light
3.00×108 m/s
Avogadro's law
"equal volumes of all gases, at the same temperature and pressure, have the same number of molecules". For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant. Ideal Gas - Avogadro came up with the notion of an ideal gas -No interactions between atoms -Atoms occupy no space -All atoms behave the same
Kinetic molecular theory for gases
- A model of an ideal gas as a collection of point particles in constant motion undergoing completely elastic collisions - Gas particles are in continuous, random motion. Collisions between gas particles are completely elastic. In other words, there is no net loss or gain of kinetic energy when particles collide. The average kinetic energy is the same for all gases at a given temperature, regardless of the identity of the gas
Avogadro's number
-the number of representative particles contained in one mole of a substance; equal to 6.02 x 10^23 particles. - Avogadro's number is a proportion that relates molar mass on an atomic scale to physical mass on a human scale. Avogadro's number is defined as the number of elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is equal to 6.022×1023 mol-1 and is expressed as the symbol NA.
Difference between classical mechanics and quantum mechanics
- Classical mechanics adequately describes the motions of bodies much larger then atoms, while quantum mechanics describes the motions of subatomic particles and atoms as waves - Classical Mechanics deals with the motion of objects under forces or their own momentum. ... Quantum Mechanics deals with the behavior of objects at the microscopic level where matter and energy start to mathematically converge because both can be observed to have wave-like behaviors at the level of Planck's constant.
Anion
- a negatively charged ion
Cation
- a positively charged ion
Electron Geometry
- geometrical arrangement of electron groups - The geometric arrangement of orbitals containing the shared and unshared electron pairs surrounding the central atom of a molecule or polyatomic ion.
Difference between bonding orbitals and antibonding orbital
-Electrons in bonding orbitals stabilize the molecule because they are between the nuclei. They also have lower energies because they are closer to the nuclei. ... Antibonding orbitals are at higher energy levels than bonding orbitals -Bonding orbitals place most of the electron density between the nuclei of the bonded atoms. Antibonding orbitals place most of the electron density outside the nuclei.
standard state
-In chemistry, the standard state of a material (pure substance, mixture or solution) is a reference point used to calculate its properties under different conditions. -Standard state conditions are defined by Standard Temperature & Pressure (STP) with a temperature of 0 oC or 273.15 Kelvin (K) and a pressure of 1 atmosphere (1 atm = 101 325 Pa), temperature. At STP (Standard Temperature & Pressure) 1 mol of ideal gas occupies 22.4 L. -Here are the conditions for a standard state set of data - Gases are at 1 atm - Solutions are at 1 M -Temp is usually at 25°C (other temp can be specified) -Elements or compounds are in their most stable form for the stated temperature When a ΔH value is under standard state conditions, it is given
Difference between kinetic and potential energy
-Potential Energy is the stored energy in an object or system because of its position or configuration. Kinetic energy of an object is relative to other moving and stationary objects in its immediate environment. Potential energy is not relative to the environment of an object. -Potential energy is the stored energy in an object due of its position or its configuration whereas Kinetic energy is the energy which a body possesses because of its motion
pressure volume work
-Pressure-volume work (or PV work) occurs when the volume V of a system changes. PV work is often measured in units of litre-atmospheres where 1L. atm = 101.325J. -The meaning of work in thermodynamics, and how to calculate work done by the compression or expansion of a gas. Key Points: Work is the energy required to move something against a force. The energy of a system can change due to work and other forms of energy transfer such as heat. Gases do expansion or compression work following the equation: work=−PΔV
Relationship between molar volume, molar mass and density
-The molar volume, symbol Vm, is the volume occupied by one mole of a substance (chemical element or chemical compound) at a given temperature and pressure. It is equal to the molar mass (M) divided by the mass density (ρ). Density(d)=m/V
standard enthaply of formation
-The standard enthalpy of formation is the enthalpy change in the formation of one mole of a substance in its standard state from elements in their standard form H2(g)+12O2(g)→H2O(l)ΔHf!=−285.8kJ -The standard enthalpy of formation is defined as the change in enthalpy when one mole of a substance in the standard state (1 atm of pressure and 298.15 K) is formed from its pure elements under the same conditions. -The standard enthalpy of formation is a measure of the energy released or consumed when one mole of a substance is created under standard conditions from its pure elements. The symbol of the standard enthalpy of formation is ΔHf. Δ = A change in enthalpy o = A degree signifies that it's a standard enthalpy change. f = The f indicates that the substance is formed from its elements
empirical formula
-a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangement of atoms. -a chemical formula showing the ratio of elements in a compound rather than the total number of atoms
Molecular Geometry
-geometrical arrangement of atoms -Molecular geometry is the three-dimensional arrangement of ATOM in a molecule
Explain Boyle's law in terms of the kinetic molecular theory.
-if V ↓, the number of collisions with the container walls per second must ↑ -therefore P ↑ -Gases can be compressed because most of the volume of a gas is empty space. If we compress a gas without changing its temperature, the average kinetic energy of the gas particles stays the same. There is no change in the speed with which the particles move, but the container is smaller. Thus, the particles travel from one end of the container to the other in a shorter period of time. This means that they hit the walls more often. Any increase in the frequency of collisions with the walls must lead to an increase in the pressure of the gas. Thus, the pressure of a gas becomes larger as the volume of the gas becomes smaller.
types of hybridization
-sp3 -combination of one s-orbital and three p-orbitals •Resultant orbitals are 109.5° apart •common in four bonded carbon compound -sp2 - the result of an s-orbital mixing with two p-orbitals •Resultant hybrid orbitals are 120° apart sp - sp hybridization is most common in compounds that have linear geometry •often accompanied by triple bonds or two doubles •A single s and p-orbital are hybridized leaving 2 unhybridized p-orbitalint
Hybridization and the role of atomic orbitals
-the mixing of atomic orbitals to produce a new set of orbitals that have characteristics of the original orbitals. (only occurs in covalent bonding) -In chemistry, orbital hybridization (or hybridization) is the concept of mixing atomic orbitals into new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory
Systematic Error
. A systematic error (an estimate of which is known as a measurement bias) is associated with the fact that a measured value contains an offset. This type of error affects all of the data by shifting it either too high or low. This is an error that is built into the apparatus and can not be reduced by repeat readings. To remove the size of the error is found and then minused from all of the results.
Conversion from calorie to joule
1 J= 0.2390 cal
Conversion from joule to calorie
1 cal= 4.184 J
Difference between ionic and covalent bonds
1) state at room temperature: covalent - liquid or gaseous, ionic - solid 2) Polarity - covalent - low, ionic - high 3) Formation - covalent - A covalent bond is formed between two non-metals that have similar electronegativities. Neither atom is "strong" enough to attract electrons from the other. For stabilization, they share their electrons from outer molecular orbit with others Ionic - An ionic bond is formed between a metal and a non-metal. Non-metals(-ve ion) are "stronger" than the metal(+ve ion) and can get electrons very easily from the metal. These two opposite ions attract each other and form the ionic bond. 4) Shape - covalent - definite shape, ionic - no definite shape 5) Melting point - covalent - low, ionic - high 6) What is it? - covalent - Covalent bonding is a form of chemical bonding between two non metallic atoms which is characterized by the sharing of pairs of electrons between atoms and other covalent bonds. Ionic - Ionic bond, also known as electrovalent bond, is a type of bond formed from the electrostatic attraction between oppositely charged ions in a chemical compound. These kinds of bonds occur mainly between a metallic and a non metallic atom. 7) Boiling point - covalent - low, ionic - hight 8) Occurs between - covalent - two -non-metals ionic - one metal and one non-metal
Differentiate between elements and compounds
1. Element: substance that cannot be chemically broken down into simpler substances. 2. Compound: substance that is composed of two or more elements. A compound contains atoms of different elements chemically combined together in a fixed ratio. An element is a pure chemical substance made of same type of atom.
Differentiate between heterogeneous and homogeneous mixtures
1. Heterogeneous Mixture: composition varies from one region of the mixture to another. They don't mix uniformly. 2. Homogeneous Mixture: have same composition throughout. They mix uniformly.
non-electrolyte
A compound that does not dissociate into ions when dissolved in water
simple cubic
A cube with an atom at each corner -atoms touch along each edge -number of atoms per unit cell is 1 -Unit cell side is twice the atomic radius (2r) -Coordination# is 6 (number of atoms in direct contact) -Low packing efficiency (lots of empty space)
heat
A form of energy that flows between two samples of matter because of their differences in temperature.
node and how it applies to quantum mechanics
A node is a point where the electron probability is zero. In chemistry, quantum mechanical waves, or "orbitals", are used to describe the wave-like properties of electrons. Many of these quantum waves have nodes and antinodes as well. The number and position of these nodes and antinodes give rise to many of the properties of an atom or covalent bond.
describe how polar bonds translate into net dipole moments for molecules
A nonpolar covalent bond is one in which the electrons are shared equally between two atoms. A polar covalent bond is one in which one atom has a greater attraction for the electrons than the other atom. So the dipole moment is calculated for the system. ... Dipole moment generally decides the polarity of the molecule -Even though the total charge on a molecule is zero, the nature of chemical bonds is such that the positive and negative charges do not completely overlap in most molecules. Such molecules are said to be polar because they possess a permanent dipole moment. A good example is the dipole moment of the water molecule.
Proton
A positively charged particle within a nucleus ... The number of protons in an element's nucleus is called the atomic number.
precipitation reaction
A reaction in which a solid, insoluble product forms upon mixing two solutions Precipitation reactions occur when cations and anions in aqueous solution combine to form an insoluble ionic solid called a precipitate.
precipitate
A solid, insoluble ionic compound that forms in, and separates from, a solution
state function
A state function is a property whose value does not depend on the path taken to reach that specific value.
strong electrolyte
A substance that completely dissociates into ions when dissolved in water 1. salts (ionic compounds excluding bases) 2. strong acids HCl, H₂SO₄, HNO₃, HBr, HI, HClO₃, HClO₄ 3. Strong bases group one hydroxides and Ca, Sr, Ba Hydroxides
weak electrolyte
A substance that does not completely ionize in water and only weakly conducts electricity in solution
structural formula
A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds. These formulas show exactly how atoms in a compound are attached to each other •they may or may not indicate actual geometry •usually used only with molecular compound
wave function
A wavefunction is a function describing the probability of a particle's quantum state as a function of position, momentum, time, and/or spin. Wavefunctions are commonly denoted by the variable Ψ. Also Known As: wave function
Atomic Mass Unit
AMU - 1/12 of the mass of a carbon -12 atom it is a unit of mass used to express atomic masses and molecular masses.
soluble
Able to dissolve to a significant extent, usually in water
Acids
Acids are substances that give many foods a sour taste Citric acid in fruit Phosphoric acid in cola Other acids are industrial: Hydrochloric acid - HCl Nitric Acid - HNO3 Called acids because they produce H+ or H3O⁺ ions in solution Often identified by H first in formula
Periodic Table
All elements are defined by a 1 or 2 letter symbol. The atomic number listed on top tells us the number of protons and vice-versa
strong acids
An acid that completely ionizes in solution
weak acids
An acid that does not completely ionize in water
aqueous solution
An aqueous solution is a solution in which the solvent is water. I
Isotope
An atom that has the same number of protons but different number of neutrons
How do lone pairs affect the shape of a molecule?
An extra lone pair or two could decrease the amount of bonding angles of the central atom, which'll change the shape of a molecule. There are many molecular shapes or geometries including linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral. These shapes listed are the basic shapes of molecular geometry and have zero lone pairs. As you may have guessed, this means that the more advanced shapes have one or more lone pairs involved.
formation of ionic compound from its elements
An ionic compound is formed by the complete transfer of electrons from a metal to a nonmetal and the resulting ions have achieved an octet. The protons do not change.
diffusion
Diffusion is the process of one substance spreading out to occupy space -In terms of gases, they occupy the space uniformly -Let's think about smells •Molecules are moving at hundreds of mph, yet they take time to reach your nose Diffusion is a study in chaos Gas molecules collide with other molecules Prevents smell molecules getting from Pt A to Pt B Temperature increases speed, but also increases # of collisions Has little effect
sharing of electrons in a covalent bond
An ionic compound is formed by the complete transfer of electrons from a metal to a nonmetal and the resulting ions have achieved an octet. The protons do not change. Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability. Nonmetals will readily form covalent bonds with other nonmetals in order to obtain stability, and can form anywhere between one to three covalent bonds with other nonmetals depending on how many valence electrons they posses. Although it is said that atoms share electrons when they form covalent bonds, they do not usually share the electrons equally.
Define the properties, allowed values and letter designations of the angular momentum quantum number, I
Angular Momentum (l) -Determines the shape of the orbital -numbers start at 0 and go up to n-1 -l = 0, 1, 2, 3,..., n-1 -if n=1, l=0 -if n=2, l=0 or 1 -the number of possible l-values will be equal to n -The value of l is often related through a letter designation of the orbital Value of I Letter Designation I = 0 s I = 1 p I = 2 d I= 3 f
Law of Conservation of Mass and who created it
Antoine Lavoisier said "in a chemical reaction, matter is neither created nor destroyed". The total mass of the substances involved in the reaction does not change.
Arrhenius definition for acids and bases
Arrhenius theory, theory, introduced in 1887 by the Swedish scientist Svante Arrhenius, that acids are substances that dissociate in water to yield electrically charged atoms or molecules, called ions, one of which is a hydrogen ion (H +), and that bases ionize in water to yield hydroxide ions (OH −).
Explain Avogadros law in terms of the kinetic molecular theory.
As the number of gas particles increases, the frequency of collisions with the walls of the container must increase. This, in turn, leads to an increase in the pressure of the gas. Flexible containers, such as a balloon, will expand until the pressure of the gas inside the balloon once again balances the pressure of the gas outside. Thus, the volume of the gas is proportional to the number of gas particles.
What is the difference between atoms and molecules?
Atoms are basic particles that compose ordinary matter. Molecules are what atoms become when they bind together in specific geometrical arrangements. Atom is the smallest particle in an element. Molecules are formed by the combination of two or more atoms. Unlike atoms, molecules can be subdivided to individual atoms. The atoms are bonded together in a molecule. An atom has a nucleus surrounded by electrons. The electrons are negatively charged particules and the nucleus contains neutrons and positively charged protons.
Bases
Bases are substances that form hydroxide (OH-) ions in solution These substances tend to taste bitter NaOH KOH Ca(OH)2
binary acids
Binary acids have only two elements - hydrogen and a non-metal Hydro - (base name of non-metal + -ic) - acid List: hydrofluoric acid. HF. hydrochloric acid. HCl. hydrobromic acid. HBr. hydriodic acid. HI. phosphoric acid. H3PO4. nitrous acid. HNO2. Nitric acid. HNO3. sulfurous acid. H2SO3.
Boyle's law
Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship, when temperature is held constant. Gases have some unique properties -They compress by decreasing volume Available space to move decreases and there are more collisions •This has the effect of increasing pressure •Robert Boyle noticed a pattern between pressure and volume measurements for a given sample -As the volume was decreased, the pressure would increase •As volume was increased, pressure decreased -Pressure and volume have an inverse relationship •Mathematically, he could show that P x V = constant (fixed T)
oxyacids
Contain hydrogen and an oxyanion. i.e. NO3⁻, SO42⁻, PO43⁻... They are named based on the name and ending of the oxyanion oxyanions ending with -ate: (base name of oxyanion + -ic) - acid oxyanions ending with -ite: (base name of oxyanion + - ous) - acid List: nitric acid HNO3 nitrous acid HNO2 perchloric acid HClO4 phosphoric acid H3PO4
Emission Spectrum
Each element has a characteristic pattern of wavelengths
effusion
Effusion is the process by which a gas flows through a tiny hole Balloons losing their gas Effusion is controlled by molecular weight Generally studied as a comparison between two gases The rate of effusion of a gas is also inversely proportional to the square root of either the density or the molecular weight of the gas.
Law of Conservation of Energy
Energy can be converted from one form to another but can neither be created nor destroyed. and total energy remains constant
Potential Energy
Energy due to position or composition.
Kinetic Energy
Energy due to the motion of the object.
3 postulates of the kinetic molecular theory
I found 5 - so I don't know why I have an extra two: 1) A gas is composed of a large number of particles called molecules (whether monatomic or polyatomic) that are in constant random motion. 2) Because the distance between gas molecules is much greater than the size of the molecules, the volume of the molecules is negligible. 3) Intermolecular interactions, whether repulsive or attractive, are so weak that they are also negligible. 4) Gas molecules collide with one another and with the walls of the container, but these collisions are perfectly elastic; that is, they do not change the average kinetic energy of the molecules. 5) The average kinetic energy of the molecules of any gas depends on only the temperature, and at a given temperature, all gaseous molecules have exactly the same average kinetic energy.
Compare density of ice and water
Ice is less dense than water. The ice structure takes up more volume than the liquid water molecules, hence ice is less dense than liquid water.
Explain Dalton's law in terms of the kinetic molecular theory.
Imagine what would happen if six ball bearings of a different size were added to the molecular dynamics simulator. The total pressure would increase because there would be more collisions with the walls of the container. But the pressure due to the collisions between the original ball bearings and the walls of the container would remain the same. There is so much empty space in the container that each type of ball bearing hits the walls of the container as often in the mixture as it did when there was only one kind of ball bearing on the glass plate. The total number of collisions with the wall in this mixture is therefore equal to the sum of the collisions that would occur when each size of ball bearing is present by itself. In other words, the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases.
Face Centered Cubic
In a face-centered cubic, there is an atom at each corner, as well as half an atom at each face There are 4 atoms in each unit cell 8(1/8) + 6(1/2) = 4 atoms
Tetrahedral - molecular geometries
In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron.
Trigonal bipyramidal
In chemistry a trigonal bipyramid formation is a molecular geometry with one atom at the center and 5 more atoms at the corners of a triangular dipyramid.
Interference
Interactions between waves ( Note: there are two types of interference: Constructive and Destructive).
interference
Interactions between waves ( Note: there are two types of interference: Constructive and Destructive).
What is a mass number and the symbol represents it?
It is the sum of neutrons and protons in an atom and is represented by the symbol A. It also can me written as X-A. Ex: Ne-20
Define the properties and allowed values of the magnetic quantum number, mi
Magnetic Quantum Number (ml) -Determines the orientation of an orbital in space -ml has integer values that range from -l to +l -if l=1, ml can be -1, 0, +1 -if l=2, ml can be -2, -1, 0, +1, +2
Differentiate between mixtures and pure substances
Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule. 1) Mixture - Substance composed of two or more particles in proportions that can vary from one sample to another 2) Pure Substance - made up of only one type of particle and its composition does not vary from one sample to the other. Particles that compose a pure substance can be individual atoms or a group of atoms joined together. Ex: helium b/c it's made up of helium atoms; water is made up of water molecules; and sodium chloride is made up of sodium chloride units.
who organized the modern form of the periodic table in order to group together elements with similar characteristics?
Mendeleev
I know the SI base units for length, mass, time and temperature
Meter (m) = Length Kilogram (kg) = Mass Second (s) = Time Kelvin (K) = Temperature
Neutron
Neutral partials witching a nucleus. They contain no electrical charge subatomic particle found in the nucleus of atoms that differs from the other subatomic particles (called "protons") in the nucleus of atoms because neutrons have no (zero) charge whereas each proton has a positive charge of +1.
Constructive interference
Occurs when a wave combines to make a wave with a larger amplitude.
Destructive interference
Occurs when two wave combine to make a wave with a smaller amplitude.
orbital penetration
Penetration describes the proximity to which an electron can approach to the nucleus electron penetration is defined by an electron's relative electron density (probability density) near the nucleus of an atom. Electrons in different orbitals have different wavefunctions and therefore different radial distributions and probabilities (defined by quantum numbers n and ml around the nucleus). In other words, penetration depends on the shell (n) and subshell
Define Properties and Allowed values of the principal quantum number, n
Principal Quantum Number (n) - Determines size and energy of an orbital. - Possible values are integers greater than 0 (n=1, 2, 3...) - Energy of an electron in an orbital can be calculated:E1 = -2.18 x 10-18 J
Random error
Random error is always present in a measurement. It is caused by inherently unpredictable fluctuations in the readings of a measurement apparatus or in the experimenter's interpretation of the instrumental reading.
Cubic Closest Pack
See picture in Lecture 36 In this structure, the first two layers form exactly as for the hcp structure The third layer, however, does not line up with either the first or second layers A third unique layer is formed Abbreviated ccp ABCABCAB
Hexagonal closed pack
See picture in Lecture 36: The first layer of atoms get as close as they can The second layer will go into the gaps The third layer for this structure lines up with the first layer Abbreviated hcp ABABABABA
standard temperature and pressure
Standard Temp = 0º C (273 K) Standard Pressure = 1 atm The conditions of T = 0° C (273 K) and P=1 atm; used primarily in reference to a gas; also known as standard conditions
empirical formula steps
Steps for Determining an Empirical Formula: 1)Start with the number of grams of each element, given in the problem. 2) Convert the mass of each element to moles using the molar mass from the periodic table. 3) Divide each mole value by the smallest number of moles calculated. 4) Round to the nearest whole number.
molecular formula steps
Strategy: 1) Get the mass of each element by assuming a certain overall mass for the sample (100 g is a good mass to assume when working with percentages). (.7546) (100 g) = 75.46 g C. ... 2) Convert the mass of each element to moles. ... 3) Find the ratio of the moles of each element. ... 4) Use the mole ratio to write the empirical fomula.
interaction between water as a solvent and different solutes dissolved in it
Thanks to its ability to dissolve a wide range of solutes, water is sometimes called the "universal solvent." However, this name isn't entirely accurate, since there are some substances (such as oils) that don't dissolve well in water. Generally speaking, water is good at dissolving ions and polar molecules, but poor at dissolving nonpolar molecules.
Bohr model
The Bohr model suggested that electrons orbit the nucleus at fixed distances like planets -this model gave electrons specific energies corresponding to observed energies When electrons absorb applied energy, they move to a higher energy state, but seek to return to the lower state. The move from a higher state to a lower state meant that energy had to be released. The energy corresponds to a wavelength of light. The hydrogen spectrum could be calculated exactly. Bohr model failed for all other elements
What unit system do scientists use?
The International System of Units (SI).
energy
The ability to do work or produce heat
Energy
The ability to do work or produce heat.
Mole
The amount of a substance that contains 6.02 x 10^23 representative particles of that substance The unit of a mole gives us a way of counting a large number of items with smaller numbers
molar heat capacity
The amount of energy, transferred as of one MOLE of a substance by one kelvin.
Unit Cells
The basic structural unit of a crystal structure A lattice is comprised of repeating patterns of atoms called unit cells. X-Ray diffraction allows us to see where the atoms are in a crystalline lattice the lattice is the most thermodynamically stable arrangement of atoms
Diffraction
The bending of waves around a barrier or through an opening.
diffraction
The bending of waves around a barrier or through an opening.
Body-centered coordination number and edge length
The body-centered cubic (bcc) has a coordination number of 8 and contains 2 atoms per unit cell -edge length (a) = 4r/SQRT(3)
body centered cubic
The body-centered cubic structure has a full atom at the center of the cell as well as an atom at each corner Each unit cell has 2 atoms in it 8(1/8) + 1 = 2 atoms
effect of changes in temperature and pressure
The critical temperature is the temperature above which the substance can no longer liquefied Regardless of the pressure applied The vapor pressure of the substance at the critical temperature is called the critical pressure This is the minimum amount of pressure needed to liquefy the gas at the critical temperature
Radioactivity
The emission of elementary particles by some atoms when their unstable nuclei disintegrate (see half-life). Materials composed of such atoms are radioactive. (See alpha radiation, beta radiation, and gamma radiation.)
Face -centered coordination number and edge length
The face-centered cubic (fcc) has a coordination number of 12 and contains 4 atoms per unit cell. -Edge length (a) = 2*SQRT(2)r
Dalton's law of partial pressures
The law stating that the sum of the partial pressures of the components in a gas mixture must equal the total pressure The sum of the partial pressures of all the gases adds up to the total pressure PT = PA + PB + PC +... We can apply the gas law to the partial pressure of each gas PAV = nART
Interaction with the EM Spectrum
The light that we see with our eyes makes up the small portion of the EM spectrum called visible light The EM spectrum contains many types of light ranging from radio waves to gamma radiation. Radio waves, Microwaves, infrared, visible ultraviolet, x-rays, gamma
mole fraction of a component in a mixture
The number of moles of a component in a mixture divided by the total number of moles in the mixture The mole fraction of A can be found by comparing either pressures or number of moles PA/P=nA/n=ΧA(molefraction) or PA=ΧAP
Atomic Number
The number of protons in a atom's nucleus and is given the symbol Z
octet rule
The octet rule is a chemical rule of thumb that reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.
How potential energy is related to the formation of chemical bonds
The point at which the potential energy reached its minimum represents the ideal distance between hydrogen atoms for a stable chemical bond to occur.
partial pressure
The pressure due to any individual component in a gas mixture When mixtures of gases are in a vessel, the pressure exerted by each gas is independent of the other gases-Amount of pressure is proportional to the fractional amount of each gas-The amount of pressure exerted by each gas is its partial pressure
Simple Cubic coordination number and edge length
The simple cubic has a coordination number of 6 and contains 1 atom per unit cell. -edge length (a) = 2r where r is the radius of the atom or ion
Relationship between speed and molar mass
The speed of the molecules in a gas is proportional to the temperature and is inversely proportional to molar mass of the gas. In other words, as the temperature of a sample of gas is increased, the molecules speed up and the root mean square molecular speed increases as a result.
thermal equilibrium
The state of two or more objects or substances in thermal contact when they have reached a common temperature
Inverse relationship between bond length and bond strength
The stronger the bond, the shorter the bond - Bond length is defined as the distance between the centers of two covalently bonded atoms. The length of the bond is determined by the number of bonded electrons (the bond order). The higher the bond order, the stronger the pull between the two atoms and the shorter the bond length
difference between the system and surroundings
The system consists of those molecules which are reacting. The surroundings are everything else; the rest of the universe. For example, say the above reaction is happening in gas phase; then the walls of the container are part of the surroundings.
difference between electron and molecular geometry
The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron geometry. . However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
Clausius-Clapeyron Equation
The vapor pressure of a liquid at different temperatures is dependent on the heat of vaporization, ∆Hvap. The relationship between temperature and vapor pressure is not linear, but can be put into a linear form
Thermal Energy
Thermal energy is the internal energy of an object due to the kinetic energy of its atoms and/or molecules. The atoms and/or molecules of a hotter object have greater kinetic energy than those of a colder one, in the form of vibrational, rotational, or, in the case of a gas, translational motion.
dipole moment
This is a measurement of the charge separation in a molecule ❖This is affected by the polarity of individual bonds ❖Polarity is caused by differences in electronegativity -This separation of charge leads to a dipole ❖Molecules that have a dipole are called polar
kinetic energy
This is the energy associated with motion Governed by both mass and velocity KE = 1/2 mv2 The units used are important Mass is in kg , velocity is in m/s
identify acid-base reaction
To determine whether a substance is an acid or a base, count the hydrogens on each substance before and after the reaction. If the number of hydrogens has decreased that substance is the acid (donates hydrogen ions). If the number of hydrogens has increased that substance is the base (accepts hydrogen ions).
calculate molarity of a solution
To get molarity we still need to divide moles of solute by volume of solution.
weak and strong acids/bases
When we refer to acids or bases being strong, we are referring to their strength as an electrolyte strong acid - strong electrolyte with acid properties weak acid - weak electrolyte with acid properties
Molecules and atoms have a distribution of thermal energies which
changes as a function of temperature
flow of energy between system and surroundings
Two possibilities exist concerning the flow of energy between system and surroundings: 1) The system can have energy added to it, which (obviously, I hope) increases its amount and lessens the energy amount in the surroundings. 2) The system can have energy removed from it, thereby lowering its amount and increasing the amount in the surroundings. We will signify an increase in energy with a positive sign and a loss of energy with a negative sign. Also, we will take the point-of-view from the system. Consequently: 1) When energy (heat or work) flow out of the system, the system decreases in its amount. This is assigned a negative sign and is called exothermic. 2) When energy (heat or work) flows into the system, the system increases its energy amount. This is assigned a positive sign and is called endothermic.
Differentiate between valence and core electrons
Valence electrons are those occupying the outermost shell or highest energy level of an atom while core electrons are those occupying the innermost shell or lowest energy level.
orbital
Wave function for a one-electron atom in the state (n, l, m)
pressure from a molecular point of view
What causes gas pressure? ▸pressure is the force exerted by the collisions of atoms/molecules with a surface ▸force per unit area (i.e. - pounds/in2) ▸The fewer collisions with a surface, the less pressure exists, and vice-versa -There are several units that you will see for pressure ▸mm Hg, in Hg, torr, atmospheres, bars, psi, Pascal, etc. ▸Our most common units will be atmospheres (atm) and torr (equal to mm Hg) ▸760 mm Hg = 760 torr = 1 atm
atomic spectroscopy
When atoms absorb energy, they often re-emit that energy in the form of light - atomic spectra Even though we may see a single color of light, there are usually several wavelengths being emittedwe can separate those wavelengths through a refractive device like a prism
Distinguish between paramagnetic and diamagnetic atoms/ions?
Whenever two electrons are paired together in an orbital, or their total spin is 0, they are diamagnetic electrons. Atoms with all diamagnetic electrons are called diamagnetic atoms. A paramagnetic electron is an unpaired electron. An atom is considered paramagnetic if even one orbital has a net spin.
Importance of reporting correct units with measurements
Without units, the results are unclear and it is hard to keep track of what each separate measurement entails. Units of measurement are the terms that we use to describe the size of something. You probably know that units include things like seconds, kilograms, meters, and so forth. Without standard units of measurement, scientists would have a huge problem understanding what other scientists were saying.
work
Work is done when a force moves an object.
Calculations and Unit Cells
X-Ray diffraction can find unit cell dimensions There is a relationship between the atomic weight, unit cell dimension, cell type, and density These calculations generally involve lots of unit conversion
molecular formula
a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of the atoms.
oxidation
a chemical reaction that involves the loss of an electron, the addition of oxygen and an increase of the oxidation number.
solution
a homogeneous mixture of two or more substances in a single phase
Intensive Properties of Matter
a property that depends on the type of matter in a sample, not the amount of matter. (Intensive Properties can be helpful clues to identifying unknown substances. a property that depends on the type of matter in a sample, not the amount of matter. (Intensive Properties can be helpful clues to identifying unknown substances.
oxidation-reduction (redox) reactions
a reaction in which electrons are transferred from one reactant to another
kilocalorie
a unit of energy of 1,000 calories (equal to 1 large calorie)
Natural Abundance
abundance of isotopes of a chemical element as naturally found on a planet when a natural element has a roughly constant percentage of isotopes
heat capacity
amount of heat required to raise the temperature of a system by a given amount
Chemical Symbol
an abbreviation of a chemical element, symbols in a periodic table
Ion
an atom that has obtained a charge - either + or -.
Electronegativity and periodic trends
an atom's ability to attract electrons when bonded with other atoms. -So, as you move down a group on the periodic table, the electronegativity of an element decreases because the increased number of energy levels puts the outer electrons very far away from the pull of the nucleus. Electronegativity increases as you move from left to right across a period on the periodic table.
Spectator Ions
an ion that is not directly involved in a chemical reaction; an ion that does not change oxidation number or composition during a reaction
reduction
any process in which electrons are added to an atom or ion (as by removing oxygen or adding hydrogen)
All gases at the same temperature have the same
average kinetic energy
Electrons and Photons behave in similar ways
both can act as particles and as waves
Both temperature and pressure
can affect phase changes
spin quantum number (ms) can have what values?
can have values of +1/2 and -1/2
de Broglie's Wavelength
de Broglie Wavelength The wavelength of an object with mass is determined by its kinetic energy For an electron - the faster it's moving, the shorter its wavelength This relationship is called the de Broglie relation λ (wavelength)=h (Planck's Constant)/mv (mass, velocity)
Identify the properties that differentiate the phases of matter
density, molar volume, molecular shape, and strength of intermolecular forces.
electron shielding
describes the attraction between an electron and the nucleus in any atom with more than one electron shell. Shielding effect can be defined as a reduction in the effective nuclear charge on the electron cloud, due to a difference in the attraction forces of the electrons on the nucleus.
chemical energy
energy stored in chemicals associated with the bonds between atoms
A pair of electrons does not have to be shared
equally between two atoms. Unequal sharing results in a polar covalent bond.
A pair of electrons, one from each of two atoms
forms a bond or bonding pair that helps each atom achieve an octet. The two atoms can also share two pairs of electrons (a double bond) or three pairs of electrons (triple bond).
Ionic compounds are composed of
formula units and not discrete molecules
Explain Charles's law in terms of the kinetic molecular theory.
if T ↑, average kinetic energy of molecules ↑, so average force of collisions ↑ therefore V ↑ to keep P (# of collisions per second) constant -The average kinetic energy of the particles in a gas is proportional to the temperature of the gas. Because the mass of these particles is constant, the particles must move faster as the gas becomes warmer. If they move faster, the particles will exert a greater force on the container each time they hit the walls, which leads to an increase in the pressure of the gas. If the walls of the container are flexible, it will expand until the pressure of the gas once more balances the pressure of the atmosphere. The volume of the gas therefore becomes larger as the temperature of the gas increases.
insoluble
incapable of disssolving in water or being extremely difficult of solution
combustion
is a common redox reaction
node
is a point where the electron probability is zero. As with all orbitals the number of radial nodes increases with the principle quantum number (i.e. the 2s orbital has one radial node, the 3s has two etc.).
Charles Law
is an experimental gas law that describes how gases tend to expand when heated. A modern statement of Charles' law is: When the pressure on a sample of a dry gas is held constant, the Kelvin temperature and the volume will be directly related. -A similar set of properties exists between Volume and Temperature •At a constant Pressure -As Temp rises, Volume rises -As Temp decreases, Volume decreases
VSEPR theory
is based on electron groups that repel each other
potential energy
is the energy stored in the interactions between objects or particles
wavelength
is the physical distance between crests of the light wave
thermal energy
is the sum of kinetic energy and potential energy in the particles that make up a material
Density
mass per unit volume of a substance Relationship between mass and volume D=Mass/Volume
Examples of Kinetic Energy
mechanical, thermal, electric, light, sound
Nucleus
nucleus is the positively charged center of the atom consisting of protons and neutrons.
octahedral electron geometries
octahedral molecular geometry describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron.
Intermolecular forces
originate from the interactions between charges, partial charges, and temporary charges on molecules, atoms and ions.
Polar molecules have
permanent dipoles that attract each other through dipole-dipole interactions
Bonds can range from a nonpolar covalent bond to a
polar covalent bond to an ionic bond depending on the difference in electronegativity between the two atoms
Extensive Properties of Matter
property that depends on the amount of matter in a sample Extensive properties, such as mass and volume, depend on the amount of matter that is being measured.
sign conventions
q (heat) + system gains thermal energy - system losese thermal energy w (work) + work done on the system - work done by the system E (change in internal energy) +energy flows into the system - energy flows out of the system
Heat of vaporization ΔH vap is a
quantitative measure for the process of vaporization
amplitude
related to the vertical height of the crest and determines the intensity of the light
the energies of sublevels within a given principal energy level are
s<p<d<f
Pauli exclusion principle
states that no two electrons in an atom can share the same set of 4 quantum numbers •because of the spin limitation, each orbital can hold only 2 electrons This means if one is assigned an up-spin ( +1/2), the other must be down-spin (-1/2).
electrolyte
substance that dissolves in water to give an electrically conducting solution.
A phase diagram relates the states of matter for a substance to
temperature and pressure
The vapor pressure of a liquid depends on
temperature and that the boiling point of a liquid depends on the external pressure
The interaction of ions and dipoles leads to
the dissolution and solvation of ions by water and other polar liquids
solvent
the dissolving medium in a solution
Energy lost by the surroundings is equal to
the energy gained by the system and vice versa
specific heat capacity
the energy, transferred as heat, that is required to raise the temperature of one GRAM of a substance by one kelvin.
accuracy
the measure of how close a measurement is to the actual, exact value
frequency
the number of crests that pass a point in a given time
molarity
the number of moles of solute dissolved in one liter of solution
Many of the chemical properties of elements are due to.....
the number of valence electrons and elements and that elements in the same group have the same number of valence electrons
Molar volume of gas
the quantity of gas. -At STP, 1 mol of any gas occupies 22.4 Liters Volume of gas = moles of gas X 22.4 Liters/1 mol -Under these conditions, it was noticed that 1 mole of any gas occupies a volume of 22.4 L-Molar volume of any gas
Calorie
the quantity of heat that raises the temperature of 1g pure water by 1 degree Celsius
Precision
the relative proximity of a set of measurements to each other or how reproducible they are. For an individual measurement - how many places to the right of the decimal are reported.
solute
the substance dissolved in a solution
empirical formula
these give a relative number of atoms of each element in a compound (i.e. - H2O2→HO) •frequently given by certain analyses
Internal energy
total amount of all potential and kinetic energy
Joule (J)
unit of energy
what happens in an acid-base reaction
when an acid and a base are placed together, they react to neutralize the acid and base properties, producing a salt. The H(+) cation of the acid combines with the OH(-) anion of the base to form water. The compound formed by the cation of the base and the anion of the acid is called a salt.
