Physical Science Lawler test 3
solubility
"Like" dissolves "like" polar dissolves in water Polar molecules dissolve other polar molecules Nonpolar molecules dissolve other nonpolar molecules
Principles of chemical relativity
All chemical interactions are from electrostatic interactions electrostatic interaction: protons and electrons being attracted to each other 3 types of bonding: metallic = metal + metal ionic = metal + nonmetal covalent = nonmetal + nonmetal
Alpha decay
Alpha decay: alpha particle=2 protons and 2 neutrons (helium nucleus) big nucleus is unstable so it shoots out an alpha particle and becomes a smaller, more stable nucleus atomic number is decreasing by 2, and mass stays the same dangerous if hits your DNA
Magnesium and Oxygen react to form Magnesium Oxide. What do the electrons do during the reaction? Let's pretend that we have some of this stuff in this room right now. Explain in detail at least four of its properties to your neighbor.
Brittle Transparent Solid Non-conductive (unless dissolved)
semiconductor
Elements that are not quite metals and not quite non-metals Along the staircase on the periodic table Still have similar properties to metals Properties: Similar to metals because of energy band Only semiconductive because they have a band gap - a greater energy difference between filled orbitals and non filled orbitals Energy is needed to make electrons jump up and conduct electricity Heat and Conductivity: Adding heat to semiconductors gives electrons energy and places them in the empty orbitals - NOW they can conduct Semiconductors resist conduction less when hot Metals resist conduction more when hot Metals will still conduct better, though
GKENECT types of energy, how ordered they are
Gravitational---most ordered Kinetic Elastic Nuclear Electric Chemical Thermal---least ordered if going from elastic to chemical, we are increasing entropy doing this is energetically favorable--releases energy that is usable ---this is how cars work if going from electric to kinetic energy, this is not efficient. some energy is released, but much more energy and time is put into making it go up that it isn't efficient
We have lots of different energy sources out there. Rank the following in terms of efficiency. Our goal is to get to Electric Potential Energy: Coal/Natural Gas Wind Nuclear
Coal/Natural Gas (3) Wind (1) Nuclear (2)
Different bond types--properties in terms of the quantum model of the atom
Covalent --share their electrons in pairs --bonds arise from electrostatic interactions energy levels are widely spaced --bonds are localized --charge does not carry--ions/electrons are not free to move in the solid state, non conductive Ionic --bonds arise from electrostatic interactions --energy levels are widely spaced --bonds are long range --charge does not carry--ions/electrons are not free to move in the solid state, non conductive -------Like roommates who steal your food and don't give it back Metallic --bonds arise from electrostatic interactions energy levels are closely spaced --bonds are long-range --Charge carries--(electrons or ions) are free to move in the solid state --------like roommates who share food evenly
Pure aluminum metal has a melting temp. at 660 degrees Celsius. The process of liquid aluminum freezing to solid aluminum at this temp is...reversible or irreversible?
Irreversible
1 pt We see a large amount of order in the world around us from life, to currents in the air and ocean. How is this consistent with the Law of Increasing Disorder?
It is because the sun provides additional high-order energy to the world to create this order."
Balancing chemical equations
Make certain that there are equal numbers of each atom on the reactant side and the product side __H2 + __O2 = __H2O 2H2 + O2 = 2H2O multiply the subscripts by the coefficient matching a molecule to a graph: -Add up the mass numbers of the elements in the molecule ex: 3 C's, mass=12x3=36 6 H's, mass 1x6=42 -Find the graph that has the last line=42ish -Those molecules with more single bonds have more lines on the graph -Molecules with double bonds have less lines on the graph STUDY THIS Suppose we tried to react aluminum with oxygen to make aluminum oxide. First write a skeleton equation: Al + O ---> AlO Make sure compounds are correct using diatomic rules, criss-cross and Greek prefixes as needed. Al + O2 ---> Al2O3 Now balance left to right making sure the totals for each element are the same. Only change the coefficients in front of the compound or element now. Never change subscripts once the compounds are correct. 4Al + 3O2 ---> 2Al2O3
metallic bonding
Metal + metal two atoms come close to each other and their orbitals overlap two new molecular orbitals are formed, one lower in energy, one higher electrons jump to the lower energy level forming a bond if more atoms come closer together, more molecular orbitals will form Why does a metallic bond have such and such attribute--think Sea of Electrons --Millions of new molecular orbitals allow valence electrons to move easily between energy levels Delocalized valence electrons can move and aren't attached to a specific atom This holds the metal atoms together and gives metals their properties malleable---metals can bend and stretch "sea of electrons" Opaque and shiny are the same reasoning
Bonding
NOT HUGELY TESTED, HELPS LATER when atoms get near each other, their orbitals overlap and new orbitals are formed. These are called molecular orbitals ---when waves hit each other, they interfere one orbital is lower in energy and one is higher in energy -anti-bonding orbital is higher in energy -bonding orbital is lower in energy electrons move to the lower energy orbital
reversible process
No increasing disorder the total disorder of the universe remains constant If it makes sense played backwards, then it is reversible If you could see it happen in reverse, it would still make sense... ---ex. a pendulum swinging back and forth without friction ---ex. a perfect bouncy ball that bounces forever ---ex. water and ice both at 0 degrees celsius, both turning into water and ice at the same time ---Entropy is NOT increasing
mineral molecule
Strand--breaks apart in strands sheet--breaks apart in sheets weird 3D structures--breaks apart in weird 3D structures Question: Your roommate (not you of course) left some dirty dishes in the sink overnight. You look into the sink and see oil bubbles floating on top of the water. Oil is a molecule, is it covalently bonded? --yes, all molecules are covalent What do we know about the polarity of oil molecules? --non-polar--it doesn't mix with water What do we know about the structure of oil molecules? --symmetric--oil must be symmetric enough--because it's non-polar, or a carbon train---C-C-C How do the oil bubbles stick together? --dispersion forces--dispersion force is the way that non-polar molecules attract each other
The naming of ionic compounds
The metal is placed first in the name, followed by the nonmetal. The end of the nonmetal's name is replaced with -ide. For example, the name of K2S is potassium sulfide.
LED
a P-type semiconductor is bonded to a N-type semiconductor the current flows in one direction only, from the N-type region, where there are extra electrons, to the P-type region, where there are vacancies for electrons. as the electrons cross the band gap, the electron loses energy and emits a photon--which is the light we see by changing the semiconductors, the energy of the band gap changes and the energy of the photon of light changes as well--various colors of LED lights are obtained ---blue--wider gap ---red---smaller gap
matching molecules to graph
a graph of the mass spectrometry process if you take a bag of oreos and slam it against the wall, what's the biggest piece you could possibly come out with? The last tall line to the right represents the molecules that make it through without getting crushed--should be at line 78. Ignore small stub lines after that last tall line
Entropy
disorder there is always an increase in total entropy of the universe It's more probable that things will be less ordered than more ordered ex. cars and energy --chemical potential energy goes in --kinetic energy comes out ---->in creating a more ordered kind of energy, thermal energy is created ---->most of the energy is converted into a lower form so that entropy continues to increase
atoms stick together by
dispersion forces
increasing temp. (increases or decreases) disorder?
increases disorder
Beta decay
isotope--when an element is the same element (same number of protons), but has varying numbers of neutrons so they're a bit different. beta particle= negative charge with no mass (electron) neutron contains positive and negative charge making it neutral, it can kick out an electron and become positive (becoming a proton) Neutron heavy isotope is unstable so it emits a beta particle (or electron) from inside a neutron, leaving only the positive charge which changes the neutron into a proton ---a proton and an electron squished together one of the neutrons is going to split into an electron and proton proton stays in the nucleus electron gets shot out atomic number is always increasing by 1 mass stays the same ex. carbon dating--carbon turning into nitrogen via beta decay
Solubility
like dissolves like polar molecules dissolve other polar molecules nonpolar molecules dissolve other nonpolar molecules ex. oil and water--water is polar, oil is nonpolar
which type of atom has valence electrons high enough in energy that they overlap with the stacked together molecular orbitals that form the conduction band?
metal
which type of atom has valence electrons higher in the energy well?
metal
metals on the periodic table
metal + metal=metallic bonding properties: high boiling and melting temp's and high densities malleable (able to be bent without breaking) opaque shiny good conductors of heat and electricity large atoms few valence electrons low ionization energies
Three types of bonding
metallic = metal + metal ionic = metal + nonmetal covalent = nonmetal + nonmetal
opaque and shiny
metals Because of the existence of the energy band--continuous band of orbitals Any visible light photon (or infrared or ultraviolet) that hits a piece of metal will be absorbed. opaque and reflective--Light does not pass through metals "Sea of electrons" opacity--Empty orbitals are very close in energy so electrons can jump up to a higher energy level easily (visible light is absorbed) ---because metals have empty, overlapping orbitals for their electrons shiny--When the electrons jump back down to the lower energy level, they emit that same light so the metal looks reflective
Hydrogen bonding
polar molecules that have H bonded to F, O, N need to know the three elements Hydrogen bonds are "fon" ex. hydrogen bond in water---strong force bonds these elements together
work=
putting things in order. A less ordered space is more likely than an ordered space, but with work you can sort molecules.
minerals
silicate molecules connected to each other in different ways to create different kinds of rocks
Families of molecules have...
similar structures
What happens to the number of molecular orbitals as the number of atoms that come together increases? What happens to the spacing between the energy of one MO and the next one immediately above or below?
the number of MO's increases the spacing decreases
irreversible process
the total disorder of the universe increases If it doesn't make sense played backwards, then it is irreversible ---ex. a plate breaking ---ex. someone walking forward ---entropy IS increasing
unsaturated fatty acids
there is a double bond between at one pair of two carbons==2 less hydrogens shape: bent once double bonds: 1 melting/boiling point: low
Compound
two or more elements bonded together, a mixture ex. NaCl, FeO, Cu+Zn
trans fatty acids
unsaturated fatty acids manually made straight shape: straight double bonds: 1 melting/boiling point: high
Gamma Decay
unstable nucleus shifts and rearranges nucleons to a more stable arrangement too many people sitting in the back of the car, high energy state--then someone shifts just right and everyone relaxes--goes to a low energy state. The extra energy gets spit out as a gamma ray excess energy is released as a gamma ray no change in atomic number no change in mass number
After entropy occurs (for example, a wall is removed and two pools of balls mix with each other) what is the chance order would be gained again? (that the balls would un-mix spontaneously)
virtually no chance
low melting and boiling point
when you melt or boil covalent material, you are breaking the attraction between molecules, or breaking INTERMOLECULAR forces intermolecular forces are not as strong as actual bonds and are broken easier the stronger the intermolecular force, the higher the melting and boiling points ex. oxygen in the air at room temp O molecules are gaseous ex. water is a liquid at room temp. water has the strongest intermolecular force (hydrogen bonding)
electronegativity
A measure of the ability of an atom in a chemical compound to attract electrons
Covalent bonding
Nonmetal + nonmetal bonding: --Nonmetals have high electronegativity--they want electrons--so they don't give up their electrons, they share them --Orbitals of Oxygen and Hydrogen overlap and a lower energy orbital is made. Electrons are shared ------when atoms share a pair of electrons (a hydrogen and a hydrogen--neither want to give up their one electron so they share--a single bond is formed ------------single bond--each atom has a filled valence shell and the electrons are in the lowest energy orbital possible, highest probability of finding electrons will be in between the two atoms -------when atoms share two pairs of electrons (an oxygen and an oxygen) it forms a double bond. ------------double bond stronger than a single bond, highest probability of finding electrons will be in between the two atoms -------when atoms share three pairs of electrons (a nitrogen and a nitrogen) a triple bond is formed. --------------triple bond stronger than a double bond, highest probability of finding electrons will be in between the two atoms -------quadruple bonds are rare and only form between some types of transition metals---so don't worry about them transparent: --because there are fewer atoms and electrons in a molecule than there are in a crystal or metal network, there are also fewer energy levels and these energy levels tend to be more widely spaced in energy. --When atoms bond, their orbitals overlap and make new molecular orbitals --Valence electrons move to the lower energy molecular orbital creating a bond --Visible light doesn't have enough energy to make the electrons jump to a higher energy level Visible light passes right through making covalent molecules transparent Polarity: --Atoms don't share electrons evenly in molecules --If one atom is more electronegative than the other, then it will pull the electrons in the bond closer to itself making one side of the molecule partially negative, and one side partially positive --If the molecule is symmetrical, then it will be nonpolar --Diatomic molecules like Cl2 are nonpolar --CO2 is nonpolar --CO is polar --carbon chains are also nonpolar--fatty acids low melting and boiling point: --only weak interactions between molecules---so covalently bonded materials are usually gases or liquids at room temp. --When you melt or boil covalent material, you are breaking the attraction between molecules, or breaking INTERMOLECULAR FORCES. --Intermolecular forces are not as strong as actual bonds and are broken easier --The stronger the intermolecular force, the higher the melting and boiling points Nonconductive: --Electrons are localized in their orbitals so they do not move --Molecules are neutrally charged overall --There is no charge that can be moved Some ways carbon (+4) can satisfy the octet rule since it can't form quadruple covalent bonds-- 1) to have each carbon atom form a single bond with four neighboring carbon atoms. This forms a lattice structure that we called diamond---This structure causes a diamond to be very strong and to have an extremely high melting temperature 2) Graphite is the second structure that carbon forms--sheets of carbon atoms arranged---There are covalent bonds between the carbon atoms in the same sheet but the interaction between the carbon atoms in the different sheets is very different. Some of the electrons are in orbitals that are delocalized on the surface of the sheet. These electrons form a very weak version of a covalent bond between the sheets. This allows the sheets to "slide" past another and makes graphite very useful as a lubricant. 3) The third form is called a buckminsterfullerene. It looks like a tiny carbon soccer ball--- have many interesting properties that are only beginning to be studied. They do have a free electron, however, and can, therefore, conduct electricity. Currently, they are being used in nanotechnology. Atoms don't share electrons evenly--electrons will spend more time near the atoms with high electronegativities and less time near the atoms with lower electronegativities--one side more positive and other a little more negative--POLAR bond ----the separation of positive and negative charges due to the polar bond is called a dipole -------the dipole is stronger if the charges are separated more. ------------a polar molecule can result if the dipoles of the individual parts of the molecule add up to create a total dipole for the entire molecule Questions: When do polyatomic ions form crystals? ---when they combine with metal atoms to form salts, and when they combine with other non-metal atoms When are molecules conductors of electricity? --when they are combined with metals and are then melted or dissolved Ammonium nitrate (NH4NO3), a common fertilizer, is an ionically bonded substance involving two polyatomic ions, ammonium (NH4+) and nitrate (NO3−). Ammonium nitrate dissolves well in a polar solvent such as water. Which of the following statements best describes what happens when this fertilizer dissolves in water? --The compound breaks up into the two oppositely charged ions. The ions do not break apart. How would you describe the melting point of a substance formed by a substance containing molecular ions? --high Which is a true statement about melting and boiling points in materials made of covalent molecules? -- Hydrogen bonding between molecules increases melting and boiling points. What best describes how oxygen molecules would behave if mixed with water? --They would dissolve poorly or not at all because they are not polar. In carbon tetra-chloride, CCl4, what is true about the charge distribution? --The chlorine will be more negative than the carbon. Which of the following would best describe the characteristics of covalent materials? --A non-conducting material with low melting and boiling points, likely liquid or gas at room temperature. Which of the answers is the correct chemical formula to represent the reaction?---(a carbon with 4 hydrogen molecules + two oxygen molecules with 2 oxygens each) --𝐶𝐻4 + 2𝑂2 = 𝐶𝑂2 + 2𝐻2𝑂 Magnesium and Oxygen react to form Magnesium Oxide. What do the electrons do during the reaction? Let's pretend that we have some of this stuff in this room right now. Explain in detail at least four of its properties to your neighbor. -Brittle -Transparent -Solid -Non-conductive (unless dissolved)
catalyst
a catalyst lowers the activation energy required for a reaction catalysts speed up a reaction without changing the outcome
Element
one atom from the periodic table ex. C, N, O, Na, Fe, etc
diatomic molecules
some elements don't like to be alone: H, N, F, O, I, Cl, Br will always be H2, N2, F2, O2, I2, Cl2, Br2 H has to either be bonded to at least another H or another molecule NEVER WILL BE FOUND BY THEMSELVES!! MEMORIZE THESE---when you do equations you have to check for these Have No Fear Of Ice Cold Beer It is more stable for them to be bonded with another same element ex. H2 or N2 periodic table: start with H, go to element 7 and drop a 7 shape Suppose we tried to react aluminum with oxygen to make aluminum oxide. First write a skeleton equation: Al + O ---> AlO Make sure compounds are correct using diatomic rules, criss-cross and Greek prefixes as needed. Al + O2 ---> Al2O3 Now balance left to right making sure the totals for each element are the same. Only change the coefficients in front of the compound or element now. Never change subscripts once the compounds are correct. 4Al + 3O2 ---> 2Al2O3
The Law of Increasing Disorder
states the total amount of disorder in the universe either remains the same (for a reversible process) or increases (for an irreversible process)
fatty acids
families of molecules have similar structures Types of fatty acids: Trans Saturated Unsaturated Polyunsaturated bending lowers boiling/melting point straight raises boiling/melting point dispersion forces impacts shape?
How does your body get energy? __C6H12O6 + __O2 = __CO2 + __H2O (the numbers after the elements are the sub numbers of the elements)
first __=1 second __=6 third __=6 fourth __=6
intermolecular forces
forces BETWEEN MOLECULES (not elements) that hold them together only with COVALENT bonds Other kind of bonds don't have these forces 1) hydrogen bonding 2) Dipole-dipole forces 3) dispersion forces 3 types of bonds are ionic, covalent, metallic
Families
molecules with similar bonds (in the same family or columns in periodic) have similar IR spec graphs
polyunsaturated fatty acids
more than one double bond between carbon molecules shape: bent multiple times double bonds 2+ melting/boiling point: lowest
Molecule
A group of elements bonded together in specific ratios with specific bonds ex. H2O (water), C02 (carbon dioxide), etc
which of the following trends have the highest melting and boiling points? atomic, molecular, or network matter
Network matter
half life problems
-To solve Half-life problems: Question: If the activity of a radioactive substance drops to 1/16 its initial value in 12 hours, its half life is -Write down what is known---starts at 100%, drops to 1/16 (makes 4 hops (1/2-1/4-1/8-1/16)), in total 12 hrs by the fourth hop -Write down what you need to figure out---need to figure out how many hours passes between each hop=it's half life -Include units---12 (hrs) /4 (hops)= 3 hrs each hop is the answer Question: what is the fraction at 12 hrs for a substance with a 3 hr half life? we know: starts at 100%, takes 12 hrs to get to a certain fraction, each hop is 3 hrs. 1 hop-1/2=3 hrs, 2 hops-1/4=6 hrs, 3 hops-1/8=9 hrs, 4 hops-1/16=12 hrs= 1/16 is the answer
Your roommate (not you of course) left some dirty dishes in the sink overnight. You look into the sink and see oil bubbles floating on top of the water. Oil is a molecule, is it covalently bonded? What do we know about the polarity of oil molecules? What do we know about the structure of oil molecules? How do the oil bubbles stick together?
1) yes all molecules are covalent 2) non-ppolar 3) symmetric 4) dispersion forces
endothermic reaction
A reaction that ABSORBS energy in the form of heat boring and cold
exothermic reaction
A reaction that releases energy in the form of heat we can use this energy---it's preferable to endothermic reactions
Mass spectrometry
Break up a bunch of molecules by shooting them with electrons, then weigh each chunk that comes out Mass of 1--hydrogen Mass of 2--could be helium, or 2 hydrogens DON'T NEED TO KNOW ALL THE SPECIFICS charged pieces accelerated to a magnet larger pieces detected and mass measured masses of different fragments of original molecule placed on a graph
why does concentration affect the reaction rate of two solutions?
Because in order for a reaction to take place, the atoms must get close enough together for their electron orbitals to overlap and a "collision" to occur. If the concentration (or pressure or temperature) is higher, there are more opportunities for collisions to occur and the reaction rate is faster.
Intermolecular Force
Forces BETWEEN MOLECULES that hold them together electromagnetic forces holding one , molecule to another molecule are quite weak, especially when compared to the forces of covalent bonds molecules can have polarity. This occurs when the electron distribution is unequal between atoms. While the total charge on the molecule is still zero, that charge isn't spread out evenly. That uneven charge distribution will cause electromagnetic interactions between individual molecules. 1)Dispersion Forces --weakest bond but most universal --for nonpolar molecules --temporary shift of electrons creating slight polarity --even non-polar atoms and molecules, such as helium and carbon dioxide, can have short-lived polarity due to the random fluctuations in electron density around the atoms--Dispersion forces are the result of these short-lived polarities. --increase with the size of the molecule --ALL atoms and molecules experience dispersion forces 2)Dipole-Dipole Forces --next strongest bond --for polar molecules --positive attracted to negative and vice versa---Dipole-dipole interactions come about as the negative side of one polar molecule interacts with the positive side of another polar molecule, like magnets --Because the difference in charge is smaller than what occurs in hydrogen bonding, so is the size of the electromagnetic attraction---a bit lower melting and boiling temps. --polar molecules and ionic materials dissolve better in a polar solvent because the opposite charges of the polar molecules or ions attract each other.---like dissolves like 3)Hydrogen Bonding ---strongest bond --misleading name--not a real bond --special case of dipole-dipole force --if hydrogen bonds with fluorine, fluorine really wants hydrogen's electron, pulls the hydrogen near itself and it becomes a very strong force --polar molecules that have H bonded to F, O, N --oppositely charged atoms in different molecules attract each other--leads to higher melting and boiling temps ex. H20 water Hydrogen likes to have FON
IR spectrometer
Help us know what atoms are in a molecule by shining light on them infrared light is shone through some sample the light transmitted through the sample is detected kind of like the discrete spectra except we can't see infrared light bonds in the molecule absorb light and bend or stretch different bonds have different energies so they absorb different frequencies of light IR spec graphs--- -Lines at the top of the graph show the frequency of light going through the sample -Dips=bonds dips show the frequency of light being absorbed by electrons in bonds Molecules in the same family have similar IR spectra graphs, similar dips light source--->polarizer--->sample--->analyzer--->detector
Order of energy
Highest to lowest ordered: Gravitational potential Kinetic Elastic Nuclear potential Electric potential Chemical potential Thermal GKENECT increasingly disordered = higher entropy when you go to a more disordered energy, you are gaining more energy from that--takes less energy to go down to a more disordered energy you have to put a ton more energy into converting a disordered energy to a more ordered energy ---ex. you put chemical potential energy into a car, and kinetic energy comes out---but that can't happen, so some energy has to come out as thermal energy ---its impossible for a car to be 100% efficient Question: You put room-temperature water into an ice-making tray and put it into your freezer. As the water cools and then becomes a solid, what happens to the entropy of the universe? Entropy goes up water is more ordered
Ionic bonding
Metal + nonmetal It's hard to break these apart--The Electromagnetic Force is VERY powerful these form because the energy of the resulting product is lower in energy, and the entropy of the universe increases. The metal loses the electron completely and the nonmetal gains it completely They become ions ionic materials are held together by electromagnetic attraction ---don't form molecules, they form network matter --------resulting compound is called an ionic compound or a salt Naming of ionic compounds--the metal is placed first and then the nonmetal. the end of the nonmetal's name is replaced with -ide. Ex. the name of K2S is potassium sulfide charge--look on periodic table--columns from left to right (skipping middle section) +1, +2, +3, +4, -3, -2, -1, 0 criss cross rule for chemical formula-- charge for Mg is +2 and P -3----formula would be Mg3P2 (subscript numbers) can go the opposite way too--start with chemical formula Fe2O3 (subscript numbers) Fe would have a charge of +3 and O a charge of -2 High melting and boiling temps: The very powerful Electromagnetic Force causes the attraction between neighboring ions, and it is hard to break all of them apart at the same time. Non conductive: Once the nonmetal has its extra electrons and the metal has gotten rid of what it needed to, there is no way the electrons will move around anymore. conductivity in metals comes because electrons are mobile and move about freely, and this is not the case with ionic compound The electrons are bound to their ions = cannot conduct electricity The ions themselves are stuck in place = cannot conduct electricity If the ionic compound is dissolved, then the ions are free to move around and can conduct electricity If dissolved in water, the ions are free to move and it conducts electricity better, but not as well as electrons do since their mass is more. Brittle: When moved, the ions find themselves next to a like charge, causing them to repel by electromagnetic force and break easily Transparent: Visible light does not have enough energy to get the electron to jump up to the next energy level. So it passes right through, and we can see it on the other side. Why would you use copper in your wiring? it is malleable (can be squished), it conducts electricity, and has a high melting point (electricity hot), and ductile (they can be stretched) -Metals conduct electricity -Metals have high melting temperatures (wires get hot!) -Metals and malleable and ductile, meaning they can be molded and stretched into thin wires without breaking
metals and nonmetals and semiconductors
Metals are on the left of "the staircase" Nonmetals are on the right Semiconductors are found along the black staircase line which divides metals from nonmetals on the periodic table --not quite metals and not quite nonmetals --have higher ionization energies and more valence electrons Only semiconductors have a band gap--the have their energy band split into two parts-- ----bottom band--filled energy band and called the valence band ----top band--unfilled energy band and called the conduction band -----Band gap in between where there are no orbitals --------band gap gives semiconductors different properties than metals---at low temp's not able to conduct electricity because their valence band is full and the electrons are not free to move about as they do in a metal. When the temp. is raised the electrons may gain enough energy to jump across the band gap into the conduction band, allowing electrons to move about freely - can give semiconductors better conductivity if you heat them up enough--places electrons in the empty orbitals when metals are hot they'll resist conductivity but still conduct
Most wiring in your house is likely copper wiring. Explain at least three reasons why copper, or more broadly, metal, is used.
Metals conduct electricity Metals have high melting temperatures (wires get hot!) Metals and malleable and ductile, meaning they can be molded and stretched into thin wires without breaking
Essay ---What are four characteristic properties of metals? How does a metallic bond cause each of these properties?
Metals generally have high melting and boiling temperatures Metals generally are good conductors of heat and electricity Metals are generally malleable Metals are generally opaque and reflective A metallic bond causes high melting and boiling temperatures because there are strong attractive interactions between the nuclei and the sea of electrons. Strong interactions require more energy to break, so the melting/boiling temperatures must be higher. A metallic bond causes the conductivity of heat and electricity because the sea of electrons are the mobile charge carriers for electricity. The electrons can also absorb or give up heat easily, transporting energy because of their mobility. A metallic bond causes the malleability of metals because the sea of electrons serve as lubricant and allow the layers of the nuclei to slide past one another. The repulsive forces from one nucleus on another nucleus are reduced by the moving electrons. A metallic bond causes opaqueness because the energy band exists. Because of the continuous band of orbitals, any visible light photon that hits a piece of metal will be absorbed. Some of the absorbed photons are immediately radiated back from the surface and appear as reflected light, causing a metallic luster or reflectivity.
Alloys
Mixing two metals to form a new metal with different properties Because metals have few valence electrons, they have low ionization energies and the electrons are able to move freely, the network matter structure of the metal is not destabilized if the type of atom is replaced with another atom that has similar properties. Bronze = Copper + Tin Brass = Copper + Zinc Coin Metals = Copper + Aluminum + Nickel Same bonding structure but usually stronger overall energy is lowered and the entropy of the universe increases Generally not as good of a conductor of electricity and heat Will often melt at a lower temp. May be less malleable than pure metals and may weigh less
A refrigerator causes a transfer of thermal energy from a cooler region to a hotter region. The separation of hot and cold causes an increase in order. The door on the refrigerator is left open. (a)What happens to the temperature of the kitchen? Explain your answer using the Law of Increasing Disorder. (b)If the fridge door were shut, order would appear to increase with the separation of hot and cold. Explain how this is possible using the Law of Increasing Disorder.
The type of energy a fridge uses is electrical potential energy A) If it senses there's a molecule hotter than the rest it kicks it out--back of the fridge is warm. --- Electrical potential energy is converted into thermal energy ---As this process is happening, the room is actually getting warmer because as you go from a higher ordered energy to a more disordered energy, you are releasing energy into the world, and it will get hotter. ---When the cold air comes out of the fridge, the hot air is trying to get into the fridge and more thermal energy is being released. So when you open the fridge, the fridge works to get it out. So this will keep happening, fridge working overtime until heat up B) when you shut the fridge door, the temp in the fridge will go down. You have created order in the fridge. There is more order than was created by the reaction before when the door was left open. ---What is happening is that there is order in the fridge now. The change in entropy of the universe = change of entropy of the system + change in entropy of the surroundings ---In order to make the air cold in the fridge, the fridge had to do work. All the work done converted a lot of electric potential energy into thermal energy. All the heat released heated the room up. Entropy in the surroundings increased more than the system. You get a net increase in entropy in the universe.
nuclear strong force
What holds the nucleus together embarrassing 5th grade problem--+ and + repel but they still are combined together in the nucleus?? protons repel each other and don't want to be close, but the strong force is more powerful, keeping the nucleus squished together Strong force has a very small reach (about the size of Fe nucleus) if an atom gets too big, the electromagnetic repulsion is stronger than the strong force and the atom breaks apart---this is when decay happens
article
answer all parts of the question! goal is to see whether you can use info from class and the article to answer the question if it says provide examples, provide at least three burning carbon coal and gas: starts with chemical and going to electrical energy going from less order to more order, not efficient bad for environment --pros and cons nuclear energy: takes nuclear energy and turns it into electric more efficient--more order to less order not as bad for environment wind turbines: kinetic energy to electric energy more favorable, going from more to less would have to put wind turbines everywhere, not much wind everywhere, bad for birds, not sufficient to power the whole world solar power: another form of nuclear power sun--nuclear process nuclear to electric energy relatively efficient not always sunny outside solar panels expensive not high production rate of energy using this way hydro...putting a dam into water: gravitational potential energy into electric energy bad for the environment nuclear vs chemical first two
polarity
atoms don't share electrons evenly in molecules if one atom is more electronegative than the other, then it will pull the electrons in the bond closer to itself, making one side of the molecules partially negative, and one side partially positive Polar-- ---If the electronegativity difference between the two atoms is between 0.5 and 2.0, the atoms form a polar covalent bond. ---if the electronegativity difference between two atoms is less than 0.5, the bond is considered non-polar (truly non-polar molecules are identical atoms like H2) ---If the electronegativity difference between the atoms is greater than 2.0, the bond is ionic. Ionic compounds are extremely polar molecules. if the molecule is symmetrical, then it will be nonpolar Diatomic molecules like CI2 are nonpolar CO is polar CO2 is nonpolar Polar molecules: CO +3 and -2 = 1 water H20 -2 and +1 = -1 Ammonia NH3 -3 and +1 = -2 Sulfur dioxide SO2 -2 and -2 = 0 Hydrogen sulfide H2S +1 and -2 = -1 Ethanol C2H60 +4 +1 -2 = 3 Nonpolar molecules: Carbon dioxide CO2 +4 -2 = 2 Benzene C6H6 +4 +1 = 5 Carbon tetrachloride CCl4 +4 -1 = 3 Methane CH4 +4 +1 = 5 Ethylene C2H4 +4 +1 = 5 Any homonuclear diatomic elements (H2 gas, N2, O2, Cl2) +1 +1 = 2, Any of the noble gasses (He, Ne, Ar, Kr, Xe) FIRST figure out if any bonds are polar---electronegativity difference >0 ---if no, then molecule is not polar ---if yes, proceed to second step--> SECOND if there are polar bonds, look at the symmetry of the molecule--> symmetrical--nonpolar nonsymmetrical (or bent)--polar --if yes symmetrical, are all outside atoms the same? ---if yes, then molecule is nonpolar--if no then molecule is polar --if no symmetry, molecule is polar
dipole-dipole forces:
attraction between POLAR molecules positive attracted to negative and vice versa H--Cl positive H lines up with the Cl H-Cl H-CL H-CL
dispersion forces
between NONPOLAR molecules temporary shift of electrons creating slight polarity increase with the size of the molecule 0=0 bond between 0=0
Nuclear Fission
breaking up a nucleus into smaller ones high a nucleus with a neutron and it breaks up creates chain reaction mass energy decreases when the large, unstable nucleus breaks up into smaller, more stable ones Nuclear "power" commercial power plants will be using fission for now until we figure out how to use fusion efficiently this is happening in the sun pros: --Low activation energy --Efficient (a lot more energy out than we put in--not as much as fusion, but it doesn't take as much energy to keep it going or activate it) --Easy chain reaction ---not as bad for the environment as burning fossil fuels and gas Cons: 1) The fuel is relatively expensive and rare. Naturally occurring uranium (which is rare enough as it is) contains too little of the 235235U isotope to work as a fuel. A difficult and expensive process must be used to enrich the natural uranium with enough 235235U to make it suitable for fuel 2) The byproducts of the reactor have dangerous radioactivity. These waste materials have to be stored for very long periods of time in a place that is likely to be geologically stable. 3) There is danger of the fuel being misappropriated for weapons. This is most critical with plutonium, but uranium is an issue as well. 4) Mistakes made at the reactors can result in serious accidents that create dire environmental and health hazards. --not very abundant fuel resource--we'll run out of uranium eventually (235U) --Radioactive material is produced (damages cells, causes cancer)
nuclear fusion
combining nuclei to make a bigger one mass energy decreases when they combine releasing lots of energy Pros: 1) The fuel is inexpensive and readily available (lots of hydrogen in the atmosphere and water) 2) It doesn't release greenhouse gases that could cause global warming as fossil fuels do---releases more energy than fission does 3) The fuel and byproducts are not useful in making weapons. 4) There is no risk of a catastrophic nuclear accident. If the reaction gets out of control, the plasma will cool down by striking the walls of the container. 5) The radioactive byproducts are relatively easy to contain and dispose of --Lots of fuel for it (Hydrogen is plentiful in the atmosphere and the ocean --Releases a LOT of energy (more than fission)---better for us to use --Doesn't release any radioactive material Cons: --Has a super high activation energy---have to slam nuclei together at a high temp/pressure --We use more energy to create fusion than it gives us in return---not efficient--same amount of energy out as we put in
reaction graphs
endothermic reaction exothermic reaction activation energy---how much energy you have to put into something to get it to react
You put room-temperature water into an ice-making tray and put it into your freezer. As the water cools and then becomes a solid, what happens to the entropy of the universe?
entropy (disorder) of the universe goes up
saturated fatty acids
every bond is attached to a hydrogen---no double bonds shape: straight double bonds: 0 melting/boiling point: highest
High Melting and Boiling Point
metals Lots of heat required to melt metals There are strong attractive interactions between the nuclei and the "Sea of electrons"---this strong interaction requires more energy to break, therefore the temperatures must be higher --Positively charged atom surrounded by negative charge (electrons) --Strong electromagnetic attraction keeping the atoms held together - lots of heat required to break them apart --The Electromagnetic Force is VERY powerful, and it is hard to break all of them apart at the same time.
malleable
metals Metals can bend and stretch "Sea of electrons" Electrons serve as lubricant--allow the layers of the nuclei to slide past one another. Repulsive forces from one nucleus on another nucleus are reduced by the mobile electrons. If the metal atoms are moved, then the electrons will rearrange to keep them bonded together
good conductors of heat and electricity
metals good conduction--needs to have a medium that moves charge freely --sea of electrons Metals conduct both heat and electricity well "Sea of electrons" electrons are the mobile charge carriers for electricity Electrons are delocalized and can move freely carrying the charge through a metal Delocalized electrons also carry kinetic energy transferring heat easily
what type of atom has the highest ionization energy?
non-metal they're all on the far right and toward the top side of the periodic table
Non-metals on the periodic table
on the far right side of the periodic table on the right side of the black staircase line Properties: poor conductors of heat/electricity brittle little/no metallic luster most can gain electrons easily small atoms many valence electrons high ionization energies
Mass energy
on the left side of Fe, the mass of the nucleons decreases as you fuse them together (fusion) on the right side of Fe, the mass of the nucleons decreases as you break them apart (fission) nucleons--protons and neutrons not all protons and neutrons weigh the exact same when you fuse things together, the mass decreases--you start on the left side of the graph --But law of conservation? They lose mass in the form of mass energy--lots of energy released go from big elements to smaller elements--when you fission things, you start on the right side of the graph and it releases energy EX: If all of us go into diff rooms by ourselves, and weigh ourselves--each are 100lbs (ex Hydrogen) Then we all come back and weigh ourselves again together and individually we each weigh 80lbs Summary: The mass of the nucleus changes depending on what atom you put it in --right side of the graph--lose mass by going away from each other, mass of nucleons decreases as you break them apart (fission)--you could do fusion on this side, but you'd have to put energy in --left side of the graph--lose mass by coming together, mass of nucleons decreases as you fuse them together--you could do fusion on this side, but you'd have to put energy in and not get much out SO can we use iron for fission? We'll end up putting in more energy than we'll get out read the graph!! look at slide 78
In an irreversible process, the (ordered or less ordered) snapshot of time comes first? for example a box with a vacuum and a box with gas molecules in it. Which one comes first?
ordered a box with a vacuum comes before gas molecules enter and create entropy
