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107 Cards in this Set

  • Front
  • Back
In the convention AX, where
Z
X is a particular atom, what do A and Z represent?
Z is the atomic number
A is the mass number
Electrons farthest from the nucleus are called what?
Valence electrons
One amu is defined as what?
One amu is defined as exactly 1/12 the mass of the carbon-12 atom (approx. 1.66 x 10^ -24 g).
What is the atomic weight of an atom?
The weight in grams of one mol of a given element expressed in g/mol.
A mol is a unit used to count particles and is represented by Avogadro's number.
What is a mol?
A mol is a unit used to count particles and is represented by Avogadro's number (6.022 x 10^ 23).

For example, the atomic weight of carbon is 12.0g/mol, which means that 6.022 x 10^ 23 carbon atoms weight 12.0g.
What is an isotope?
For a given element, multiple species of atoms w/ the same number of protons, but different numbers of neutrons exist. These are isotopes.
Isotopes generally exhibit the same chemical properties since they still have the same number of protons and electrons.
Equation for the energy value of a quantum?
E=hf
h is a proprtionality constant known as Planck's constant = 6.626 x 10^ -34 Jxs.
f, sometimes designated v, is frequency of the radiation.
Equation for the angular momentum of an electron?
angular momentum = nh / 2pi
h is Planck's constant
n is a quantum number that can be any positive integer.
How is the energy of an electron related to its oribal radius?
The smaller the oribal radius, the lower the energy state of the electron.
The smallest radius, or orbit, an electron can have corresponds to n=1, which is the ground state of the hydrogen electron.
Why do atoms of any element generally exist in the ground state?
All systems tend toward minimal energy. Thus, atoms generally exist in the ground state unless subjected to high temperatures of irradiation.
What gives rise to fluorescence?
Emission
When electrons are excited to higher energy levels, this excited state lasts only a brief time. The electrons rapidy return to the ground state, emitting energy in what form?
Photons
Equation to determine the electromagnetic energy of photons (emitted by electrons returning from an excited state to the ground state)
E=hc/ λ

h is Planck's constant
c is velocity of light (3 x 10^8
λ is wavelength of the radiation.
What is the atomic emission spectrum?
Different electrons are excited to different energy levels. When these electrons return to their ground states, each emits a photon w/ a wavelength characteristic of the specific transition it undergoes.
Each element has a unique AES b/c each element can have its electrons excited to different distinct energy levels.
Can be used as a fingerprint for the element.
The light emitted doesn't produce a continuous spectrum, but light at specific frequencies known as a line spectrum.
What is the atomic absorption spectrum?
When an electron is excited to a higher energy level, it must absorb energy. The energy absorbed as an electron jumps from one orbital or lower energy to an orbital of higher energy is characteristic for that transition.
Wavelengths of absorption correspond directly to wavelengths of emission, b/c energy difference remains unchanged.
Can be used for identification of elements present in a gas phase sample.
Absorption is the basis for color of compounds.
What is the basis for color of compounds?
Absorption
What does the Heisenberg uncertainty principle state?
It is impossible to determine, w/ perfect accuracy, the momentum and the position of an electron simultaneoulsy.
What are the four quantum numbers?
n - principal quantum number.
l - angular momentum (azimuthal) quantum number.
ml - magnetic quantum number.
ms - spin quantum number.
What is the principal quantum number?
The first quantum number, denoted by the letter n.
Can take on any positive integer value.
The larger the value of n, the higher the energy level and radius of the electron's orbit.
The max. number of electrons in energy level n is 2n^2.
Difference in energy b/t adjacent shells decreases as distance from the nucleus increases.
What is the angular momentum quantum number?
The second quantum number, dentoed by the letter l.
Refers to the subshells or sublevels that occur w/in each principal energy level.
For any given n, the value of l can be any integer in the range of 0 to n-1.
The four subshells corresponding to l=0,1,2,3 are known as s,p,d,f subshells respectively.
Max. number of electrons that can exist w/in a subshell is given by 4l+2.
Greater the value of l, the greater the energy of the subshell.
For any value n, there will be n possible values for l.
What is the magnetic quantum number?
The third quantum number, denoted by ml (m of l).
Specifies the particular orbital w/in a subshell where an electron is likely to be found at a given point in time.
Possible values for ml are all integers from l to -l including 0.
The shape and energy of each orbital are dependent upon the subshell in which the orbital is found.
What is the spin quantum number?
The fourth quantum number, denoted by ms.
The spin of a particle is its intrinsic angular momentum and is a characteristic of a particle, like a charge.
The two spin orientations are +1/2 and -1/2.
Two electrons in the same orbital must have opposite spins.
Electrons in different orbitals w/ the same ms values have parallel spins.
What does the notation 2p^4 indicate regarding electron configuration?
Indicates there are 4 electrons in the p (2nd) subshell of the 2nd principal energy level.
What is Hund's Rule?
Hund's rule states that w/in a given subshell, orbitals are filled such that there are a maximum number of half-filled orbiatals w/ parallel spins.
Electrons "prefer" empty orbitals to half-filled orbitals (a pairing energy must be overcome for 2 electrons carrying repulsive neg. charges to exist in the same orbital)
What is the signifigance of electron configuration? What properties are affected?
The presence of paired or unpaired electrons affects the chemical and magnetic properties of an atom or molecule.
If the material has unpaired electrons, a magnetic field will align the spins and weakly attract the atom - paramagnetic.
Materials w/ no unpaired electrons are slightly repelled by a magnetic field and are called diamagnetic.
What is a paramagnetic molecule?
A molecule which has unpaired electrons. Its magnetic field will align the electron spins and weakly attract the molecule.
What is a diamagnetic atom?
An atom which has no unpaired electrons.
The atom will be slightly repelled by a magnetic field.
What does the notation 2p^4 indicate regarding electron configuration?
Indicates there are 4 electrons in the p (2nd) subshell of the 2nd principal energy level.
What is Hund's Rule?
Hund's rule states that w/in a given subshell, orbitals are filled such that there are a maximum number of half-filled orbiatals w/ parallel spins.
Electrons "prefer" empty orbitals to half-filled orbitals (a pairing energy must be overcome for 2 electrons carrying repulsive neg. charges to exist in the same orbital)
What is the signifigance of electron configuration? What properties are affected?
The presence of paired or unpaired electrons affects the chemical and magnetic properties of an atom or molecule.
If the material has unpaired electrons, a magnetic field will align the spins and weakly attract the atom - paramagnetic.
Materials w/ no unpaired electrons are slightly repelled by a magnetic field and are called diamagnetic.
What is a paramagnetic molecule?
A molecule which has unpaired electrons. Its magnetic field will align the electron spins and weakly attract the molecule.
What is a diamagnetic atom?
An atom which has no unpaired electrons.
The atom will be slightly repelled by a magnetic field.
What is ionization energy?
The energy required to remove completely an electron from a gaseous atom or ion.

Also called ionization potential.
Does removing an electron from an atom require energy?
Yes. It requires an input of energy (endothermic).
What is the trend of ionization energy on the periodic table?
Ionization energy increases from left to right across a period as atomic radius decreases.
Ionization energy decreases moving down a group as atomic radius increases.
(The closer and more tightly bound an electron is to the nucleus, the harder it will be to remove = higher ionization energy).
What is electron affinity?
Electron affinity is the energy change that occurs when an electron is added to a gaseous atom, and it represents the ease w/ which the atom can accept the electron.
How do you calculate the formal charge of an atom?
V - 0.5N bonding - N nonbonding
where V is the number of valence electrons in the free atom.
When do nonpolar covalent bonds form?
Nonpolar covalent bonding occurs b/t atoms that have the same electronegativities.

Occurs in diatomic molecules - H2, Cl2, O2, N2.
What is a Lewis acid?
A compound that can accept an electron pair to form a covalent bond.
What is a Lewis base?
A compound that can donate an electron pair to form a covalent bond.
What is a neutralization reaction?
A type of double displacement rxn that occurs when an acid reacts w/ a base to produce a soln of salt and water.
What is a zero-order rxn?
A rxn which has a constant rate that is independent of the reactants' concentrations.

An increase or decrease in temperature is the only factor that can change the rate of a zero-order rxn.
What effect would increasing the concentration of reactants have on a zero-order rxn?
No effect, b/c the rate of a zero-order rxn is independent of reactants' concentrations.

The only factor that can change the rate is temperature.
What is Le Chatelier's Principle?
States that a system to which a stress is applied tends to change so as to relieve the applied stress.

Used to determine the direction in which a rxn at equilibrium will proceed when subjected to a stress, such as a change in concentration, temperature, pressure, or volume.
In a system at constant temperature, a change in pressure will cause a change in what?
Volume (Le Chatelier's Principle)

At constant temp., and change in volume will also cause a change in pressure.

Gases are greatly affected b/c they are highly compressible
In a system at constant temperature, how are pressure and volume related?
Pressure and volume are inversely related.

Increasing the pressure will shift the equilibrium so as to decrease the # of moles of gas present -> reduces the volume of the system relieving the stress of the increased pressure.
What is the difference between an isolated system and a closed system?
An isolated system can't exchange matter or energy w/ its surrounding, whereas a closed system can exchange energy, but not matter w/ its surroundings.
What is a closed system?
A system that can exchange energy, but not matter w/ its surroundings.
What is an isothermal process?
A system undergoes an isothermal process when the temperature of the system remains constant.
What is an adiabatic process?
A process that occurs when no heat exchange occurs.
What is an isobaric process?
A system undergoes an isobaric process when the pressure of the system remains constant.
What is the most common energy change in a chemical process.
Heat change
What is the difference b/t heat and temperature?
Heat is a specific form of energy that can enter or leave a system.

Temperature is a measure of the average kinetic energy of the particles in a system.
What is an endothermic rxn?
A rxn that absorbs heat energy.

Endothermic is positive.
What is an exothermic rxn?
A rxn that releases heat energy.

Exothermic rxns are negative.
What is calorimetry?
Measures heat changes.

Constant-volume and constant-pressure calorimetry are used to indicate the conditions under which the heat changes are measured.
Name some important state functions
Pressure, temperature, and volume.
What is a state function?
Properties whose magnitude depends on the initial and final states of the system, and not how that change was accomplished.

State functions are independent of path, but not necessarily independent of one another.
Standard conditions for measuring state functions such as enthaly, entropy,and free energy of a rxn.
25 C and 1 atm
What is enthalpy?
Enthalpy is used to express heat changes at constant pressure.

The change in enthalpy of a process is equal to the heat absorbed or evolved by the system at constant pressure.
A postive enthalpy change is endothermic/exothermic?
endothermic
A negative enthalpy change is endothermic/exothermic?
exothermic
What is the difference in standard temperature and pressure (STP) and standard state conditions?
STP refers to conditions of 273.15K (0 C) and 1 atm. STP is generally used for gas law calculations.

Standard state conditions refers to 25 C. Generally used when measuring standard enthalpy, entropy, Gibbs free energy, and voltage.
What is an ideal gas?
An ideal gas represents a hypothetical gas whose molecules have no intermolecular forces and occupy no volume.
At relatively low pressures and high temperatures, many gases behave in a nearly ideal fashion.
What does Boyle's Law state?
Boyle's Law states that pressure and volume are inversely related (when one increases, the other decreases).

PV=k, or P1V1 = P2V2
What does Charles's Law state?
States that at constant pressure, the volume of a gas is directly proportional to its absolute temperature in Kelvin (when one increases, the other also increases).

V/T = k, or V1/T1 = V2/T2
What does Avogadro's Principle state?
States that for all gases at a constant temperature and pressure, the volume of a gas will be directly proportional to the number of moles of gas present. Therefore, all gases have the same number of moles in the same volume.

n/V = k, or n1/V1 = n2/V2
What does the Ideal Gas Law state?
Combines the relationships outlined in Boyle's Law, Charles's Law, and Avogadro's Principle to yield an expression that can be used to predict the behavior of a gas.

PV=nRT
What is the Ideal Gas Law Equation?
PV = nRT

R is gas constant
R = 8.21 x 10^-2 L x atm / mol x K
or R= 8.314 J / K x mol

Use R value which matches units of variables!!
Under what conditions will a gas deviate from the Ideal Gas Law?
As the temperature becomes severely low or the pressure is increased to extemely high levels, the actual volume of the gas will be less than that predicted by the ideal gas law.
What is sublimation?
When a solid goes directly into a gas phase.

The reverse, from a gas to a solid, is called deposition.
In terms of molarity and temperature, describe how water will flow.
Water will move toward the area w/ either greater molarity or higher temperature if molarity is the same.
What is osmotic pressure?
The pressure water exerts to counterbalance the flow of water from another region.

Osmotic pressure = MRT
M is molarity of the soln.
R is ideal gas constant
T is temperature (Kelvin)
Solubility rules of various salts in water
1. All salts of alkali metals are water soluble.
2. All salts of the ammonium ion, NH4+, are water soluble.
3. All chlorides, bromides, and iodides are water soluble, w/ the exceptions of Ag+, Pb++, and Hg++.
4. All salts of the sulfate ion, SO4-, are water soluble, except Ca++, Sr++, Ba++, and Pb++.
5. All metal oxides are insoluble, w/ the exception of the alkali metals and CaO, SrO, and BaO, all of which hydrolyze to form soln's of the corresponding metal hydroxides.
6. All hydroxides are insoluble, w/ the exeption of the alkali metals and Ca++, Sr++, and Ba++.
7. All carbonates (CO3--), phosphates (PO4---), sulfides (S--), and sulfites (SO3--), are insoluble, w/ the exception of the alkali metals and ammonium.
Acid-base rxns and oxidation-reduction rxns take place in what type of soln.
Ionic
What is molarity (M)?
The number of moles of solute per liter of soln.
What is molality?
The number of moles of solute per kilogram of solvent.
Define a Bronsted-Lowry acid
Donates a proton
Define a Bronsted-Lowry base
Accepts a proton
Define a Lewis acid
Electron-pair acceptor
Define a Lewis base
Electron-pair donor
Three forms of heat:
Conduction
Convection
Radiation
First Law of Thermodynamics:
States that energy of the system and surroundings is always conserved.
Any energy change to a system must equal the heat flow into the system plus the work done on the system.

Delta E = q + w
If enthalpy change is positive, the rxn is ______?
endothermic
What is entropy (s)?
Nature's tendency to create the most probable situation that can occur w/in a system.
Nature's tendency toward disorder.
What does a negative delta G indicate about a rxn?
It is spontaneous.
What is molarity?
moles of the compound / volume of the soln.
Name the state functions
Pressure, temperature, volume
Enthalpy
Entropy
Free energy
Internal energy
What is enthalpy?
Expresses heat changes at constant pressure.
Hess's Law
States that enthalpies of rxns are additive.
Bond breakage is endothermic/exothermic?
Bond breakage is ALWAYS endothermic
Bond formation is endothermic/exothermic?
Bond formation is ALWAYS exothermic
Freezing is accompanied by a increase/decrease in entropy?
Decrease
What is the relationship of boiling and entropy?
Boiling is accompanied by a large increase in entropy.
Phase transition w/ the greatest entropy?
Sublimation
What does Gibbs' Free Energy (G) represent?
The maximum amount of energy released by a process occurring at constant temperature and pressure.
Gibbs Free Energy is at a minimum when?
At equilibrium
Does the rate of a rxn depend on Gibbs' Free Energy?
No. The rate of a rxn depends on the activation energy, not the G.
What does Boyle's Law state?
Boyle's Law states that pressure and volume are inversely related.
What does Charles's Law state?
Charles's Law states that at constant pressure, the volume of a gas is directly proportional to its absolute temperature.
What does Avogadros Principle state?
Avogadros Principle states that for all gases at a constant temperature and pressure, the volume of the gas will be directly proportional to the number of moles of gas present.
Thus, all gases have the same number of moles in the same volume.
Kinetic Molecular Theory of Gases
The average KE of a gas particle is proportional to the absolute temperature of the gas.
What are colligative properties?
Physical properties derived soley from the number of particles present, NOT the nature of those particles.
Ideal Gas Law deviations due to pressure
As the pressure of a gas increases, the particles are pushed closer and closer together.
At moderately high pressure, a gases volume is less than would be predicted by the Ideal Gas Law, due to intermolecular attractoin.
Ideal Gas Law deviations due to temperature
As the temperature of a gas decreases, the avg velocity of the gas molecules decreases, and the attractive intermolecular forces become increasingly significant.
As the temperature of a gas is reduced, intermolecular attraction causes the gas to have a smaller volume than would be predicted.
What are some colligative properties?
Freezing point depression
Boiling point elevation
Osmotic pressure
Vapor-pressure lowering (Raoult's Law)
What is an ideal solution?
A solution which obeys Raoult's Law