Chemistry

Question 1

Principal Quantum Number

Answer 1

n, describes the radial distance of an electron’s orbit from the nucleus

• Electrons orbit at fixed distances from the nucleus but the distance between orbits decreases with distance from the nucleus
• Energy increases with distance from the nucleus

Question 2

Radioactive decay

Answer 2

Unstable nuclei are said to be radioactive and they undergo a transformation to make thm more stable altering the number and ratio of protons and neutrons or just lowering the energy

Question 3

Alpha particle

Answer 3

• When a large nucleus wants to become more stable by reducing the number of protons and neutronss, it emits an alpha particle
• Particle consists of 2 protons and 2 neutrons (4/2 alpha) which is equivalent to a helium 4 nucleus so it can be denoted by 4/2 He and the decay reduces the parent’s atomic number by 2 and the mass number by 4
• Alpha particles are emitted with high energy from the parent nucleus but this energy is quickly lost as the particle travels through matter or air so the particles do not travel far and can be stopped by the outer layers of human skin or a piece of paper

Question 4

Beta decay

Answer 4

• Three types of beta decay (b-, b+, and electron capture) Each type of beta decay involves the conversion of a neuron into a proton through the action of the weak nuclear force
• Beta particles are more dangerous than alpha particles since they are less massive and have more energy and penetrating ability but can be stopped by aluminum foil or centimeter of plastic or gas

Question 5

B- Decay

Answer 5

When an unstable nucleus contains too many neutrons it may convert a neutron into a proton and an electron which is ejected. The atomic number is 1 greater than parent nucleus but the mass number remains the same. Most common type of beta decay

Question 6

B+ Decay (positron emission)

Answer 6

When an unstable nucleus contains too few neutrons, it converts a proton into a neutron and a positron which is ejected. The positron is the electron’s antiparticle (identical to an electron except charge is positive).
Atomic number is 1 less than parent but mass number remains same

Question 7

Electron Capture

Answer 7

Another way for unstable nucleus to increase its neutrons is to capture an electron from the closest electron shell and to use it in conversion of a proton into a neutron
Causes atomic number to be reduced by 1 while mass number remains same

Question 8

Gamma decay

Answer 8

A nucleus in an excited state can relax to its ground by emitting energy in the form of one or more photons of electromagnetic radiation (photons = gamma photons).

Question 9

Gamma photons

Answer 9

High frequency and energy and can penetrate most matter effectively
Ejection changes neither mass number nor atomic number

Question 10

Nuclear Binding Energy

Answer 10

Energy that was released when the individual nucleons (proton and neutrons) were bound together by the strong force to form the nucleus. It’s also equal to the energy that would be required to break up the intact nucleus into tits individual nucleons. The greater the binding energy per nucleon, the more stable the nucleus

Question 11

Mass defect

Answer 11

When the nucleons bind together to form a nucleus, some mass is converted to energy, so the mass of the combined nucleus is less than the sum of the masses of all its nucleons individually. The difference (delta m) is called the mass defect and its energy equivalent is the nuclear binding effect
delta m = (total mass of separate nucleons) - (mass of nucleus)

Question 12

Emission Spectrum

Answer 12

Gives an energetic “fingerprint” of that element because it consists of a unique sequence of bright lines that correspond to specific wavelengths and energies. The energies of the photons, or particles of light that are emitted, are related to their frequencies and wavelengths by
Ephoton = hf = h (c/wavelength)

Question 13

Energy subshell

Answer 13

Comprised of one or more orbitals and is denoted by a letter (s,p,d,f) that describes the shape and energy of the orbital

Question 14

Aufbau Principle

Answer 14

Electrons occupy the lowest energy orbitals available. Electrons subshells are filled in order or increasing energy

Question 15

Hund’s Rule

Answer 15

Electrons in the same subshell occupy available orbitals singly, before pairing up

Question 16

Pauli Exclusion Principle

Answer 16

There can be no more than two electrons in any given orbital

Question 17

Diamagnetic

Answer 17

An atom that has all of its electrons spin paired; contain an even number of electrons and have all of its occupied sub shells filled. Since all the electrons in a dia are spin-paired, the individual magnetic fields created cancel leaving no net magnetic field. Such an atom will be repelled by an externally produced magnetic field

Question 18

Paramagnetic

Answer 18

Atom’s electrons are spin-paired so the atoms are attracted into externally produced magnetic fields

Question 19

Which way do you move in periodic table if atom becomes an anion? cation?

Answer 19

Anion: right
Cation: left

Question 20

Ionization Energy

Answer 20

The amount of energy necessary to remove the least tightly bound electron from an isolated atom’s ionization energy. As we move from left to right across a period or up a group the ionization energy increases since the valence electrons are more tightly bound. IE2 always greater than IE1

Question 21

Electron affinity

Answer 21

The energy associated with the addition of an electron to an isolated atom. If energy is released when the electron is added, EA is neg. The halogens have large negative EA values since the addition of an electron would give them the desired octet configuration. So they readily accept an electron to become an anion; the increase in stability causes energy to be released. The noble gases and alkaline earth metals have positive electron affinities because the added electrons begin to fill a new level or sub level and destabilizes the electron configuration. Tend to become more neg as we move to the right or up a group

Question 22

Electronegativity

Answer 22

Is a measure of an atom’s ability to pull electrons to itself when it forms a covalent bond; the greater the tendency to attract electrons, the greater the value is

Question 23

Acidity

Answer 23

measure of how well a compound donates protons, accepts electrons, or lowers pH in a chemical system. The ease with which an acid (HX) donates its H+ is related to the stability of the conjugate base. The more electronegative the element bearing the negative charge is the more stable the anion will be. Therefore acidity increases from left to right across a period. The larger the anion, the more the negative charge can be delocalized and stabilized. Acidity increases down a group in the periodic table

Question 24

Bond dissociation energy

Answer 24

The energy required to break a bond homolytically

Question 25

Homolytic bond cleavage

Answer 25

One electron of the bond being broken goes to each fragment of the molecule so two radicals form

Question 26

Heterolytic Bond Cleavage

Answer 26

Both electrons of the electrons of the electron pair that make up the bond end up on the same atom; form a cation and an anion

Question 27

Relationship between bond order bond strength

Answer 27

The higher the bond order the shorter and stronger the bond- should only be compared for similar bonds (carbon-carbon with c-c)

Question 28

Bond order

Answer 28

Number of bonds between adjacent atoms so a single bond order of 1

Question 29

Bond length and bond strength

Answer 29

longer the bond weaker it is; the shorter the bond, the stronger it is

Question 30

Covalent bond

Answer 30

Formed between atoms when each contributes one or more of its unpaired valence electrons. The electrons are shared by both atoms to help complete both octets.

Question 31

Coordinate covalent bond

Answer 31

One atom will donate both of the shared electrons in a bond (NH3)

Question 32

Lewis base

Answer 32

-Donates a par of electrons; Can act as a ligand or a nucleophile

Question 33

Hydrogen Bond

Answer 33

- Strongest type of intermolecular force between two neutral molecules - A molecule must have a covalent bond between H and either N, O, F and another molecuele must have a lone pair of e on N, O, F

Question 34

Vapor Pressure

Answer 34

Pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of the liquid. Weaker IMF, the higher vapor pressure and the more easily it evaporates ALso temperature dependent. Vapor pressure increases with the temp of the substance. INc the average kinetic energy of the particles allows them to overcome the intermolecular forces holding them together and increases the proportion of particles that can move into the gas phase

Question 35

Ionic Solids

Answer 35

Held together by the electrostatic attractions between cations and anions in a lattice structure. Solid at room temp; The greater the charge, the stronger the force of attraction between the ions

Question 36

Network Solid

Answer 36

Atoms are connected in a lattice of covalent bonds meaning that all interactions between atoms are covalent bonds. The intermolecular forces are identical to the tintramolecular forces. Very strong and tend to e very hard solids at room temperatures.

Question 37

Network Solid

Answer 37

Atoms are connected in a lattice of covalent bonds meaning that all interactions between atoms are covalent bonds. The intermolecular forces are identical to the intramolecular forces. Very strong and tend to e very hard solids at room temperatures.

Question 38

Metallic solids

Answer 38

-Covalently bound lattice of nuclei and their inner shell elections surrounded by a sea or cloud of electrons. At least one valence electron is not bounded to any one particular atom and is free to move throughout the lattice (conduction electrons). Metals excellent conductors and malleable and ductile. Solids at room temp

Question 39

Molecular solids

Answer 39

Molecules held together by one of three types of intermolecular interactions: hydrogen bonds, dipole-dipole, or LD forces. - these forces are significantly weaker than ionic, network, or metallic bonds, molecular compounds have much lower melting and boiling points than other types of solids - Often liquids or gases at room temperature and are more likely to be solids as the strength of IMF increase

Question 40

Zeroth law of Thermodynamics

Answer 40

If two systems are both in thermal equilibrium with a third system, then the two initial systems are in thermal equilibrium with one another. If systems are in thermal equilibrium with one another, their temperatures must be the same.

Question 41

First Law of Thermodynamics

Answer 41

The total energy of the universe is constant. Energy must be transformed from one form to another, but it cannot be created or destroyed

Question 42

Enthalpy

Answer 42

Measure of the heat energy that is released or absorbed when bonds are broken and formed during a reaction that's run at constant pressure

Question 43

Exothermic

Answer 43

If the products of a chemical reaction have stronger bonds than the reactants then more energy is released in the making of product bonds than was to put in to break the reactant bonds. Energy is released. Products are in lower energy state than the reactants

Question 44

Endothermic

Answer 44

The products of a chemical reaction have weaker bonds than the reactants then more energy is put in during the breaking of reactant bonds than is released in the making of product bonds. The products are in a higher energy state than the reactants and enthalpy is positive because heat had to be added to the system from surroudings

Question 45

Second Law of Thermodynamics

Answer 45

The disorder of the universe increases in a spontaneous process. Nature has a tendency to become increasingly disorganized and another way to state the second law is that all processes tend to run in a direction that leads to maximum disorder

Question 46

Positive Delta S

Answer 46

If randomness increases or order decreases

Question 47

Entropy Cases

Answer 47

1. LIquids have more entropy than solids 2. Gases have more entropy than solids or liquids 3. Particle in solution have more entropy than undissolved solids 4. Two moles of a substance have more entropy than one mole 5. The value of delta S for a reverse reaction has the same magnitude as that of the forward reaction, but with opposite signs

Question 48

Third Law of Thermodynamics

Answer 48

Defines absolute zero to be a state of zero-entropy. Thermal energy is absent and only the least energetic thermodynamic state is available to system. If only one state is possible, then there is no randomness to the system and S=0. The least thermally energetic state and has the lowest achievable temperature

Question 49

Gibbs Free Energy

Answer 49

The energy that is free to do useful work from a chemical reaction.

Question 50

Determining Spontaneity

Answer 50

Delta H Delta S Delta G Rxn is ? - + - Spontan. + + - @high T S + @ low T NS - - + @ high T NS - @ low T S + - + NS

Question 51

Kinetics v Thermodynamics

Answer 51

Just because a reaction is thermodynamically favorable does not mean that it will be taking place rapidly. Thermo predicts spontaneity and equilibrium not rates

Question 52

Key property of a physical change

Answer 52

No intramolecular bonds are made or broken; a physical change affects only the intermolecular forces between molecules or atoms

Question 53

Heat of fusion

Answer 53

The amount of heat that must be absorbed to change a solid into a liquid

Question 54

Heat of Vaporization

Answer 54

Energy absorbed when a liquid changes to a gas

Question 55

Formula for the amount of heat accompanying a phase transition

Answer 55

q = n x delta H phase change

Question 56

Temperature Change vs Phase Change

Answer 56

In between phase changes, matter can absorb or release energy without undergoing transition as an increase or decrease in temperature. When a sample is undergoing a phase change, it absorbs or releases heat without a change in temperature. When a substance absorbs or releases heat, one of two things can happen: either its temperature changes or it will undergo a phase change but not both at the same time

Question 57

Specific heat

Answer 57

Intrinsic property that tells us how resistant it is to changing its temperature

Question 58

Temperature Change and Heat Capacity

Answer 58

Temperature change inversely proportional to the substance's heat capacity. A substance like water with a high specific heat will undergo small change in termperature

Question 59

Phase Diagrams

Answer 59

Phase of a substance doesn't depend on the temperature it also depends on the pressure. even at high temperatures, a pressure can be squeezed into the liquid phase if the pressure is high enough

Question 60

Phase Diagram for Water

Answer 60

An increase in pressure at constant temperatures can favor the liquid phase not the solid phase222222

Question 61

Volume

Answer 61

1 cm^3 = 1 cc = 1 mL and 1 m^3 = 1000 L

Question 62

Pressure conversion

Answer 62

1 atm = 760 torr = 760 mm Hg = 101.3 kPa

Question 63

Deviations from Ideal Gas Behavior

Answer 63

Attractive forces between a particle causes a decrease in pressure if the volume of the container is fixed and accounting for particle volume causes a decrease in free space if the pressure is fixed Gases behave more ideally at higher temperatures.

Question 64

Why do higher pressures and lower temperatures cause larger deviations from ideal behavior?

Answer 64

As pressure increases, gas particles become closer to one another. This accentuates the effects of attractive intermolecular forces, causing a decrease in observed pressure (preal < pideal). At low temperatures, IMF become more important. Those gases that behave most ideally have the weakest IMF and the smallest molecular weights and volumes. By maintaining conditions of high temperature and low pressure, the interactions between particles are minimized and particle volume remains insignificant compared to container size helping to favor more ideal behavior for all gases

Question 65

A container holds methane and sulfur dioxide at a temperature of 227. Let KEm denote the average kinetic energy of the methane and the KEs the average KE of the SO2 molecules. Which describes the relationship between these energies?

Answer 65

KEm= KEs | Both gases have samp temp so avg kinetic energies will be the same

Question 66

The temperature of neon gas in a glass tube is increased from 10 degrees Celsius to 160. As a result, the avg Kinetic energy of the neon atoms will increase by a factor of?

Answer 66

less than 2 | convert C to Kelvins!!!

Question 67

What happens to carbohydrates in oxidation

Answer 67

broken down to CO2

Question 68

BOnd between two sugar molecules

Answer 68

GLycosidic linkage; covalent bond formed in a dehydration reaction that requires enzyme catalysis

Question 69

Fatty acid structure

Answer 69

long unsubstituted alkanes that end in a carboxylic acid. The chain is typically 14 to 18 Carbons long and because they are synthesize two carbons at a time from acetate, only even numbered made in human cells

Question 70

Triacylglycerols

Answer 70

Storage form of fatty acid is fat (triacylglycerol). Composed of three fatty acids esterified to a gycerol molecule.

Question 71

lipases

Answer 71

enzymes that hydrolyze fats; triacylglycerols are stored in fat cells as an energy source

Question 72

Fats as Energy Storage Molecules

Answer 72

Efficient because of packing and energy content 1. Packing: hydrophobicity allows fats to pack together more closely than carbs. Carbs carry a great amount of water-of-solvation (water molecules hydrogen bonded to hydroxyl group) 2. Energy Conten: Fat molecules store much more energy than carbs

Question 73

Bond between two phosphates

Answer 73

Anhydride bond

Question 74

Why are phosphate anhydride bonds able to store so much energy?

Answer 74

1. When phosphates are linked together, their negative charges repel each other strongly 2. Phosphates have more resonance forms and thus a lower free energy than linked phosphates 3. Phosphates has a more favorable interaction with biological solvent than linked phosphates

Question 75

Intermediate

Answer 75

Substance that is produced in one elementary step and then consumed in a subsequent step. Intermediates will not pile up like dirty dishes they will shuttle back and forth between reactants and products until the slow step takes it forward.

Question 76

Rate determining step

Answer 76

Slowest step in a process

Question 77

What is reaction rate determined by?

Answer 77

- How frequently the reactant molecules collide - The orientation of the colliding molecules - Their energy

Question 78

What makes the reaction rate faster

Answer 78

1. Lower the activation energy, faster the reaction 2. The greater the concentration of the reactants, the faster the reaction rate (favorable collisions are more likely as the concentrations of reactant molecules increase) 3. The higher the temperature of the reaction mixture, the faster the reaction rate (more molecules have sufficient energy to overcome the activation energy barrier and molecules collide at a higher frequency so the reaction can proceed at a faster rate)

Question 79

Catalyst

Answer 79

Provides reactants with a different route, usually a shortcut to get to products. Will make the reaction go faster by either speeding up the rate determining step or providing an optimized route to products b lowering activation energy and energy of the highest energy transition state

Question 80

Difference between reactants and catalysts

Answer 80

Catalyst remains unchanged at the end of a reaction

Question 81

Phase Solubility Rules

Answer 81

1. The solubility of solids in liquids tends to increase with increasing temperature 2. Solubility of gases in liquids tends to decrease with increasing temperature 3. Solubility of gases in liquids tends to increase with increasing pressure

Question 82

Salt solubility Rules

Answer 82

1. All Group 1 (Li+, Na+, K+ Rb+, Cs+) and ammonium salts are soluble 2. All nitrate (NO3-) Perchlorate (ClO4-), and acetate (C2H3)2-) salts are soluble 3. All silver (Ag+) lead (Pb2+/Pb4+) and mercury (Hg2 2+/Hg2+) salts are insoluble except for their nutrates, perchlorates, and acetates

Question 83

Ka and strength of acid

Answer 83

The larger the Ka value, the stronger the acid. The smaller the Ka value the weaker the acid

Question 84

Conjugate acid and base tendencies

Answer 84

1. The conjugate acid of a strong base has no acidic properties in water. Ex: the conjugate acid of LiOH is Li+ which does not act as an acid in water 2. The conjugate acid of a weak base is a weak acid (the weaker the base, the stronger the conjugate acid) Ex: the conjugate acid of NH3 is NH4+ which is a weak acid

Question 85

Neutralization Reactions

Answer 85

When an acid and a base are combined they will react in a neutralization reaction. Oftentimes this reaction will produce a salt and water.

Question 86

Henderson Hasselbalch Equation for acid

Answer 86

pH = pKa + log (conjugate base/ weak acid)

Question 87

Henderson-Hasselbalch Equation (for base)

Answer 87

pOH= pKb + log (conjugate acid/weak base)

Question 88

Indicator

Answer 88

Weak acid that undergoes a color change when it's converted to its conjugate base

Question 89

Acid-base equivalence points

Answer 89

1. For a weak acid (titrated with a strong base) the equivalence point will occur at a pH > 7 2. For a weak base (titrated with a strong acid), the equivalence point will occur at a pH < 7 3. For a strong acid (titrated with a strong base) or for a strong base (titrated with a strong acid), the equivalence point will occur at pH=7