Kaplan: General Chemistry

True (a net dipole moment occurs when the vector sum of all of the bond dipoles is nonzero)

(T/F) A dipole moment exists when a molecule has a separation of positive and negative charges.

False (kinetic energy is directly proportional to absolute temperature)

(T/F) A gas molecule's kinetic energy is inversely proportional to the absolute temperature of the gas

False (a triple bond is shorter than single bond)

(T/F) A triple bond is longer than a single bond.

False (some atoms are capable of bonding less than an octet, like boron, and some more, like phosphorus)

(T/F) All atoms bond according to the "octet rule"

False (an oxidizing agent is a species that gains electrons and thereby causes another agent to be oxidized)

(T/F) An oxidizing agent is oxidized in an electrochemical reaction.

True (they can both be valence electrons. Nonbonding electrons are not involved in a bond, whereas bonding electrons are involved in a bond. Valence electrons are all electrons in the outermost shell and all bonding electrons)

(T/F) Both bonding and nonbonding electrons can be valence electrons

False (solids and liquids are the condensed phases)

(T/F) Gases are often referred to as the condensed phase.

False (the noble gases have stable octets, so their electron affinity is approaching zero)

(T/F) Group VIIIA elements (the noble gases) have high electron affinities.

False (heat absorbed by a system is considered positive and head lost by a system is considered negative)

(T/F) Heat absorbed by a system is considered negative and heat lost by a system is considered positive.

False (increasing pressure will shift equilibrium so as to produce fewer moles of gas)

(T/F) Increasing the pressure of a system will shift equilibrium so as to increase the number of moles of gas produced.

False (K_eq is characteristic of a given system at a given temperature)

(T/F) K_eq for a reaction remains constant at all temperatures.

True (if there is no net dipole moment within the molecule, it will be nonpolar)

(T/F) Molecules with polar bonds can be nonpolar.

False (nonmetals are generally brittle and lusterless, and are located on the upper right side of the periodic table)

(T/F) Nonmetals are found in the middle of the periodic table and are malleable, ductile, and shiny

False (polar molecules typically have higher boiling points as a result of greater intermolecular forces)

(T/F) Nonpolar molecules typically have higher boiling points than polar molecules

False (osmotic pressure is proportional to molarity)

(T/F) Osmotic pressure is proportional to molality

False (The medium can affect reaction rate by stabilizing or destabilizing compounds and intermediates)

(T/F) The medium in which a reaction takes place cannot affect the reaction rate.

False (a zero order reaction has a constant rate that is independent of the concentration of reactants)

(T/F) The rate of a zero order reaction is dependent on the concentration of the reactants.

False (the rates of effusion are inversely proportional, just as in diffusion)

(T/F) The rates of effusion for two molecules are directly proportional to the square root of their molar masses.

False (never multiply by the number of moles when adding standard potentials)

(T/F) When adding standard potentials, multiply by the number of moles oxidized or reduced first.

Diprotic base

A base that can accept two moles of protons per mole of itself (e.g., SO_4^2-)

Coordinate covalent bond

A bond in which a pair of electrons originates from just one of the atoms.

Solvation shell

A cagelike network of solvent molecules that forms around a solute in a solution

Covalent bond

A chemical bond formed when atoms share bonding electron pairs; usually have similar electronegativity values

Molecular formula

A chemical formula showing the actual number of atoms present in a certain compound

Single displacement reaction

A chemical reaction in which one atom or ion is transferred from one reactant to another in the process of the reaction (A+BC -> B+AC)

Decomposition reaction

A chemical reaction in which one substance breaks down into multiple substances.

Double displacement reaction

A chemical reaction in which two different compounds exchange an atom or ion to form two new compounds; also called a metathesis reaction.

Electrochemical reaction

A chemical reaction that either is driven by or produces electricity.

Indicator

A chemical species that changes color when undergoing dissociation. They are used to signal the equivalence point of a titration.

Intermediate

A complex that appears during the course of a reaction but does not appear in the net reaction, or as a final product.

Solute

A compound, commonly a solid, dissolved in a solvent to create a solution

Lewis definition

A definition of acids as electron-pair acceptors and bases as electron-pair donors.

Arrhenius

A definition of acids as producers of protons and bases as producers of hydroxides in aqueous solution

State function

A function that depends only on the initial and final states of a system, not on the path in between.

Transition state

A high energy complex in which old bonds are partially broken and new bonds are partially formed. Charges existing only prior to or after the formation of the complex are designated as partial charges; high energy than both the reactants and the products

Ideal gas

A hypothetical gas whose particles would occupy zero volume and have no attractive intermolecular forces

Gibbs-Helmholtz Equation

A key equation in thermochemistry, giving the relationship between the enthalpy, entropy, temperature, and Gibbs free energy. deltaG = deltaH -TdeltaS

Azeotrope

A liquid mixture of two or more substances that has its own constant boiling point, different from the boiling points of its constituents. The vapor of this unique mixture has the same composition as the liquid state, making it difficult to separate the constituents..

Electronegativity

A measure of an atom's ability to pull electron density toward itself when involved in a chemical bond. Increases from left to right and from bottom to top on the periodic table.

Solvent

A medium, commonly a liquid, into which a solute is dissolved to create a solution.

Lewis Structure

A method using lines and dots to represent valence electrons and shared pairs of electrons of atoms, ions, or molecules.

Emulsion

A mixture of immiscible liquids which are broken up into extremely small particles.

Bohr Model

A model of the atom postulating that electrons are located in descrete circular orbits about the nucleus. In this model, the electrostatic force between the positive nucleus and negative electron acts as the centripetal force keeping the electron in orbit.

Ion

A monoatomic or polyatomic particle with an electric charge

Anion

A negatively charged ion.

Cation

A positively-charged ion.

Phase diagram

A pressure versus temperature plot showing the conditions under which a substance exists in each phase - solid, liquid, or gas - and at which points those phases are in equilibrium with one another.

Isothermal process

A process in which a constant temperature is maintained.

Adiabatic process

A process in which no heat is transferred to or from the system by its surroundings.

Isochoric process

A process in which volume remains constant and in which no net pressure-volume work is done

Reversible reaction

A process than can proceed bidirectionally to form both product and reactant

Isobaric

A process that occurs at a constant pressure

Percent yield

A ratio calculated as a percentage of the actual mass of product yielded to the theoretical yield of product mass.

Concentration

A ratio of the amount of a solute to teh total amount of solution.

Reaction quotient

A ratio of the concentrations of the products to the concentrations of the reactants at a given point during a reaction, commonly denoted by the letter by Q. In the expression, each reactant and product is raised to the power of its stoichiometric coefficient.

Equilibrium constant

A ratio of the concentrations of the products to the concentrations of the reactants at a reaction's point of equilibrium, where each reactant and product in the expression is raised to the power of its stoichiometric coefficient. Commonly denoted by K_eq

Solubility

A ratio that measures the maximum amount of solute that can dissolve in a solvent at a given temperature.

Neutralization reaction

A reaction in which an acid and a bas are combined to form water and a salt.

Combination reaction

A reaction in which two or more reactants combine to form a product.

Complex reaction

A reaction that can be broken down into two or more elementary reactions

Endothermic reaction

A reaction that proceeds with the net absorption of energy (heat) from the surroundings.

Exothermic reaction

A reaction that proceeds with the net release of energy into the surroundings.

Spontaneous reaction

A reaction that will proceed or occur on its own without an input of energy from its surroundings.

Disproportionation

A redox reaction in which the same species is both oxidized and reduced.

Net ionic equation

A representation of a displacement reaction showing only the reactive species and omitting the spectator ions

Octet rule

A rule stating that atoms - except a few, such as Be, H, and B- tend to react in order to form a set of 8 valence electrons.

Kinetic molecular theory of gases

A sees of ideas used to account for the behavior of ideal gases. The theory describes gas as volumeless particles in constant, random motion that exhibit no intermolecular attractions and undergo completely elastic collisions with each other and with the walls of the container.

Quantum numbers

A set of four numbers used to describe an electron's energy state (position and energy). Since electrons cannot occupy the same position in space, no two electrons can share the same four quantum numbers.

Lyman Series

A set of spectral lines that appear in the UV region when a hydrogen atom undergoes a transition from energy levels n>1 to n=1.

Balmer series

A set of spectral lines that appear in the visible light region when a hydrogen atom undergoes a transition from energy levels N>2 to n=2.

Photon

A single particle of light, and the smallest possible discrete amount of electromagnetic energy. Its energy is equal to hf, where h is Planck's constant and f is the frequency of the light wave.

Electrolyte

A solute, usually an ionic compound, that allows its solution to conduct electricity (ex. NaCl, KI)

Buffer

A solution containing a weak acid or base coupled with its conjugate salt, acting to prevent changes to the solution's pH upon the addition of acidic or basic substances.

Saturated solution

A solution that contains the maximum amount of solute that can be dissolved in a particular solvent at a particular temperature.

Aqueous solution

A solution with water as its solvent

Amphoteric

A species capable of reacting with either a proton or hydroxide, thereby behaving as either an acid or a base.

Amphiprotic

A species that can either accept or donate a proton.

Reducing agent

A species that is oxidized in the process of reducing another species.

Oxidizing agent

A species that is reduced in the process of oxidizing another species.

Hess's Law

A statement that the enthalpy change of an overall reaction is equal to the sum of the standard heats of formation of the products minus the sum of the standard heats of formation of the reactants.

Electron

A subatomic particle of negligible charge that orbits the nucleus and has a negative charge.

Proton

A subatomic particle with a positive charge and a mass of 1.0073 amu.

Neutron

A subatomic particle with zero electric charge that is slightly heavier than a proton

Open system

A system that allows for the exchange of energy and matter across its boundaries.

Closed system

A system that allows for the exchange of energy, but not matter, across its boundaries.

Isolated system

A system that can exchange neither energy nor matter with its surroundings

Conjugate acids and bases

A systematic pairing of a protonated and deprotonated species. They appear on opposite sides of a chemical equation

VSEPR (Valence shell electron pair repulsion) Theory

A theory that states the 3-dimensional molecular geometry about a central atom is determined by the electronic repulsions between its bonding and nonbonding electron pairs.

Orbital

A three-dimensional region about the nucleus where a rapidly orbiting electron is likely to be found. Each has a unique assignment of values for the n, l, and m_l quantum numbers.

Heat

A transferable form of energy, usually in the form of kinetic energy of molecules.

Ionic bond

A type of chemical bond in which there is a complete transfer of valence electrons to form positive and negative ions that are subsequently bound by electrostatic forces.

Polar covalent bond

A type of covalent bond between atoms of different electronegativities resulting in unequal sharing of electron density. Therefore, polar bonds have partial positive and partial negative poles.

Nonpolar covalent bond

A type of covalent bond between atoms with the same electronegativities resulting in the equal sharing of electrons

Ideal gas law

A unification of Boyle's Law, Charles' Law, Gay-Lussac's Law, and Avogadro's principle into the formula that describes the behavior of ideal gases: PV=nRT

Atomic mass unit

A unit of mass that is equal to 1/12 the mass of a carbon-12 atom. It is approximately equal to the mass of a proton.

Dispersion forces

A weak intermolecular force prevalent in nonpolar covalent molecules caused by transient dipole-induced dipole attractions. Also called London forces.

Forward

According to Le Chatelier's Principle, in which direction will equilibrium shift if products are removed?

Resonance structures

Alternate Lewis diagrams of the same molecule that show the delocalization of electrons within that molecule; they retain atomic connectivity, but differ in electron distibution.

Strong acid

An acid that will completely dissociate in aqueous solution.

Titration

An analytical procedure in which a solution of known concentration is slowly added to a solution of unknown concentration to the point of molar equivalency, thereby providing the concentration of the unknown solution.

Constant-volume calorimeter

An apparatus commonly referred to as a bomb calorimeter; used to measure the amount of heat absorbed or released during a reaction.

Diamagnetic

An atom or a substance that contains no unpaired electrons and is consequently repelled by a magnet.

Paramagnetic

An atom or a substance that contains unpaired electrons and is consequently attracted by a magnet.

Free radical

An atom or molecules , usually a monoatomic halogen, that has an unpaired electron in its valence shell.

Galvanic cell

An electrochemical cell powered by a spontaneous redox reaction that produces an electric current flow; also called a voltaic cell.

Electrolytic cell

An electrochemical cell that uses an external electric source to drive a nonspontaneous redox reaction

Half-cell

An electrode immersed in an electrolytic solution that is the site of either oxidation or reduction in an electrochemical cell.

Elementary reaction

An elementary reaction is a reaction that cannot be decomposed into other reactions.

Henderson-Hasselbalch Equation

An equation commonly used in titration-based problems that relates the pH or pOH of a solution to the pK_a or pK_b and the ratio of the dissociated species. pH = pK_a + log ([A-]/[HA])

Nernst Equation

An equation used to determine a cell's electromotive force when conditions are not standard. E_cell = E^o_cell - (0.0592/n) log Q, where n is the number of moles of electrons transferred in the redox reaction and Q is the reaction quotient.

Acid dissociation constant

An equilibrium expression used to measure acid strength, given by the ratio of the product of the products' molar concentrations to the product of the reactants' molar concentrations, with each term raised to the power of its stoichiometric coefficient. Denoted by the equilibrium constant K_a.

Rate Law

An experimentally determined mathematical expression showing the rate of a reaction as a function of the concentration of its reactants and a reaction-specific constant k.

Water dissociation constant

An expression of the auto-ionization of water into H+ and OH- at a certain temperature, given by the product of H+ and OH-'s molar concentrations and is denoted by the equilibrium constant K_w., equal to 10^-14 at 25 degrees Celsius.

Charles' Law

At a constant pressure, the volume of an ideal gas is directly proportional to its temperature.

Boyle's Law

At a constant temperature, the volume of an ideal gas is inversely proportional to its pressure.

Gay-Lussac's Law

At a constant volume, the pressure of an ideal gas is directly proportional to its temperature.

Isotopes

Atoms that share the same atomic number (Z) but have a different number of neutrons, and therefore different atomic masses.

Colligative properties

Certain properties of solutions, such as vapor pressure lowering, freezing point depression, boiling point elevation, and osmotic pressure, that are affect by the number of solute particles dissolved.

Empirical formula

Chemical formula showing the smallest whole-number ratio of atoms in a compound

Bronsted-Lowry

Common definition of acids as proton donors and bases as proton acceptors.

Molarity

Concentration of a solute in a solution, found as moles of solute per liters of solution.

Molality

Concentration of a solute in solution found by calculating moles of solute per kilogram of solvent.

Faraday's Constant

Denoted by the letter F, it equals 9.65 x 10^4 coulomb per mole of electrons.

No

Do pure solids or liquid appear in an equilibrium constant expression?

Exothermic

Does a negative enthalpy correspond to an endothermic or exothermic process?

Aufbau Principle

Electrons fill an atom in order of increasing energy level, and each electron ring will fill completely before electrons begin to enter the next one

Hund's Rule

Electrons will first fill equal-energy orbitals of a subshell unpaired and with parallel spins before being coupled with other electrons of opposite spins in the same orbital. This method of maximizing the number of half-filled orbitals allows for the most stable distribution of electrons within a subshell.

Halogens

Elements in group VIIA of the periodic table; not naturally found in elemental state but rather as ions or diatomic elements; very reactive and desperate to complete octets

Alkaline Earth Metals

Elements in the group IIA of the periodic table; relatively low Zeff (bigger radii, but not as big as alkali); often for divalent cations with removal of two electrons; very reactive and are not naturally found in their elemental state

Metals

Elements that are characteristically electropositive, malleable, and ductile. These elements tend to be found on the left side of the periodic table, are lustrous, and have relatively low ionization energies and electron affinities.

Nonmetals

Elements that have characteristically high electronegativity, ionization energy, and electron affinity. These elements tend to be found on the right side of the periodic table and are poor conductors.

Properties of ionic compounds

Form crystal lattices, conduct electricity in solution, and have high melting and boiling points.

0.25 (moles of oxygen)

Given a mixture of 2 gases (oxygen and nitrogen) at TP and occupying 22.4 L, if there are 0.25 moles of nitrogen, how many moles of oxygen are there?

Decreasing activation energy

How does a catalyst increase reaction rate?

Horizontally, vertically

How does a period run in the periodic table? How does a group run?

1, 2, 3

How many equivalents of hydrogen ion are in the following: hydrochloric acid, sulfuric acid, and phosphoric acid.

None (they are isotopes, they have the same number of protons but different numbers of neutrons)

How many more protons are in a carbon 14 atom than in a carbon 12 atom?

1, 3, 5, 7

How many orbitals can each subshell (s, p, d, f) accomodate?

6.022 x 10^23

How many particles are in a mole?

temperature (characteristic reaction at a given temperature)

Keq is dependent on what?

Law of conservation of energy

Law stating that energy cannot be created nor destroyed but only transferred and transformed

Graham's Law

Law stating that the rate at which two different gases effuse or diffuse is inversely proportional to the square root of their molecular weight.

Immiscible liquids

Liquids that repel each other and do not mix to form a solution

Standard heat of formation

Measure of the heat absorbed or released wen a substance is formed from its naturally occurring elements under standard conditions.

Osmotic pressure (Pi)

Molarity * gas constant * temperature (MRT) =

Pauli Exclusion Principle

No two electrons in an atom can have the same set of four quantum number values.

Activation energy

Often denoted by E_a, it is the energy barrier that must be overcome for a reaction to proceed.

Reduction

Part of a reaction in which a species gains electrons

Oxidation

Part of a reaction in which a species loses electrons

Diffusion

Passive transport of a gas or solute throughout a medium by means of random motion.

Avogadro's Principle

Principle stating that when equal volumes of different gases are at identical temperature and pressures, they contain equal numbers of molecules.

pH

Scaled value used to measure the acidic strength of a solution, calculated by taking the negative logarithm of the molar concentration of protons in a solution.

Phases of matter

Solid, liquid, and gas, traditionally. There are other anomalous states, such as plasma, superfluid, and Bose-Einstein condensate.

Dispersion forces < dipole-dipole < hydrogen bonding < ion dipole

State the following forces in order of increasing strength: Hydrogen bonding, dispersion forces, dipole-dipole, ion-dipole.

Dalton's law of partial pressures

States that the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual components.

Quantum mechanics

Study of physics at the atomic level where energy is quantized in discrete, rather than continuous, levels.

Bond dissociation energy

The amount of energy required to break a particular bond in one mole of gaseous molecules.

Ionization energy

The amount of energy required to completely remove an electron from the orbit of an atom in its gaseous state. Increases from left to right and from bottom to top on the periodic table.

Specific heat

The amount of heat required to raise one gram of a substance by one degree Celsius.

Actual yield

The amount of product actually isolated from the reaction experimentally.

Intermolecular forces

The attractive and repulsive forces between neighboring molecules in a substance

Effective nuclear charge

The attractive force a valence electron feels from the nucleus, after accounting for the shielding effect of inner core electrons. Abbreviated Z_eff.; increases from left to right but remains constant going down a group (one more proton outweighs effect of electron)

Atomic weight

The average mass, measured in amu, of all the isotopes of a given element as they occur naturally.

Atom

The basic building block of all matter in the universe, made up of three components: protons, neutrons, and electrons.

Standard heat of reaction

The change in enthalpy of a reaction under standard conditions

Entropy

The chaos or randomness of a system, denoted by the letter S.

Formal charge

The charge assigned to an atom in a molecule or polyatomic ion, calculated by subtracting half the number of bonding electrons and all of the nonbonding electrons from the valence electron number.

Nucleus

The dense, positively charged center of an atom, which contains its protons and neutrons.

Standard electromotive force

The difference between the two reduction potential of half-cells in a cell under standard conditions.

Atomic emission spectrum

The discontinuous line spectrum of light produced when excited electrons return to their ground state and emit photons of a certain frequency.

Atomic radius

The distance measured either between the nucleus and outermost electron of an atom or by the separation of the two nuclei in a diatomic element. Decreases from left to right and from bottom to top on the periodic table (additional proton increases Zeff, reducing atomic radius)

Common ion effect

The effect by which the molar solubility of one salt is reduced when another salt, having a common ion, is brought into the same solution

Anode

The electrode at which oxidation occurs during a cell's redox reaction.

Cathode

The electrode at which reduction occurs during a cell's redox reaction.

Valence electrons

The electrons occupying the outermost electron shell of an atom that are available to participate in chemical bonds.

Transition elements

The elements found in the B groups of the periodic table. These elements contain partially filled d subshells.

Transition metals

The elements from IB to VIIIB. They are notable for their metallic character and are able to adopt multiple oxidation states.

Representative elements

The elements in the first two families and the last six families of the periodic table.

Noble gases

The elements in the last column of the periodic table. They are characterized as being very stable and unreactive due to having full electron shells.

Metalloids

The elements that have properties of metals and nonmetals; B, Si, Ge, As, Sb, Te, and Po.

Gibbs free energy

The energy of a system available to do work. deltaG represents the change in free energy following a reaction. A reaction with a negative deltaG is spontaneous, while a reaction with positive deltaG is nonspontaneous.

Electron affinity

The energy released when an atom or ion in the gaseous state gains an electron. Increases from left to right and from bottom to top on the periodic table.

Bond energy

The energy required to break one mole of a chemical bond; also called bond enthalpy.

Theoretical yield

The expected amount of product yielded in a reaction according to the reactants' stoichiometry.

Principal quantum number

The first quantum number, designated by the letter n, it takes on any positive integer value and describes an electron's energy level. An electron with a higher n value is at a higher energy state.

T_b = K_b x molality of solution

The formula for boiling-point elevation

Spin quantum number

The fourth quantum number. Designated by the m_s, it species an electron's intrinsic spin value or angular momentum within an orbital. Since there can be no more than two electrons per orbital, the value of m_s can only be +1/2 or -1/2.

Normality

The gram equivalent weight of solute per liter of solution, often denoted by the letter N.

Alkali metals

The highly reactive elements found in group IA of the periodic table (with the exception of hydrogen); low Zeff and tend to easily lose one electron; react readily with nonmetals, especially halogens

Redox half-reaction

The hypothetical equation showing only the species that is oxidized or reduced in a redox reaction and the correct number of electrons transferred between the species in the complete, balanced equation.

Reaction rate

The measure of how quickly reactants are consumed and products are formed, commonly expressed in terms of mol/L*s

Molar solubility

The molar amount of a solute that can dissolve in 1L of solvent until equilibrium - also called saturation - is reached.

Effusion

The movement of gas through a small opening into an area of lower pressure

Atomic number

The number of protons in a single atom of an element, often denoted by the letter Z.

pI

The pH of a molecule at which it contains no net electric charge; the isoelectric point.

System

The part of the universe under consideration in a process or a reaction that is separated from its surroundings by some boundary.

Henry's Law

The partial pressure of a gas dissolved in a solution is directly proportional to the partial pressure of that gas above the solution.

Vapor pressure

The partial pressure of a vapor when it is in equilibrium with its solid or liquid phase.

Electron Configuration

The patterned order by which electrons fill subshells and energy levels in an atom. The first number designates the principal quantum number (n; the letter - s, p, d, f, or g - specifies the subshell (l); and the superscript indicates the number of electrons in that subshell. For example, the configuration of oxygen is 1s^2 2s^2 sp^4.

Percent composition

The percentages by mass (in amu) of the elements making up a compound.

Sublimation

The phase change from a solid to a gas.

Solution equilibrium

The point at which a solution is fully saturated. At this point, the rate of dissociation of the solute equals the rate of its precipitation, and no further solute will dissolve.

Equivalence point

The point in a titration at which an equimolar amount of titrant has been added to the unknown solution.

Half-equivalence point

The point in a titration at which exactly half the molar equivalence of reactant is consumed by the titrant being added. At this point in an acid-base titration, the pKa of the unknown solution is revealed.

Triple point

The point on a phase diagram at which a substance exists in equilibrium between all three phases.

Partial pressure

The pressure contribution of a single gas in a container holding a mixture of gases, as given by total pressure and mole fraction.

Evaporation

The process by which a liquid becomes a gas

Crystallization

The process by which a liquid becomes a solid.

Reaction mechanism

The process of all the individual steps of a reaction, including the formation and destruction of any reaction intermediates that may occur.

Dipole moment

The product of the amount of partial charge at either end of a molecule's dipole multipled by the distance between them, given by the equation p = qd

Ion product

The product of the molar concentrations of dissociated ions in solution at a given point in a reaction, where each ion is raised to the power of its stoichiometric coefficient.

Solubility product constant

The product of the molar concentrations of dissociated ions in solution at saturation, where each ion is raised to the power of its stoichiometric coefficient. Denoted by the equilibrium constant K_sp.

Heisenberg uncertainty principle

The quantum mechanical idea that we cannot measure the exact momentum and position of an orbiting electron simultaneously. That is, the more accurately we measure an electron's momentum, the less we know about its exact position.

Limiting reagent

The reactant of a chemical equation that, given nonstoichiometric amounts, determines the amount of product that can form; the reactant that runs out first.

Molecular orbital

The region in a molecule where atomic orbitals overlap, resulting in either a stable low-energy bonding orbital or an unstable high-energy antibonding orbital

Azimuthal quantum number

The second quantum number. Designated by the letter l, it means "angular momentum" and refers to the subshell (s, p, d, f, etc.) in which the given electron resides. l can take on the value of an integer in the 0 to n-1 range.

Rate-determining step

The slowest step in a reaction mechanism that determines the overall rate of the reaction.

Chemical kinetics

The study of reaction rates and the factors that affect them

Formula weight

The sum of all the masses present in one molecule of a molecular compound.

Reaction order

The sum of the exponents in a rate law, where each exponent provides the reaction order with respect to its reactant.

Mass number

The sum of the protons and neutrons in an element, denoted by the letter A.

STP

The temperature and pressure at which an ideal gas has a mass of 22.4 liters; 273 K and 1 atmosphere.

Reduction potential

The tendency of a species to acquire electrons

Standard reduction potential

The tendency of a species to be reduced, as measured at 25 C when reacting species are of 1M concentration or 1atm partial pressure.

Magnetic quantum number

The third quantum number, designated by m_l, it describes a particular orbital within a subshell where an electron is most likely to be found. The possible values are integers in the -l to l range, including 0.

Enthalpy

The total heat content of a system at a constant pressure, commonly denoted by the letter H.

Deposition

The transition from a gas to a solid.

Fusion

The transition from a solid to a liquid.

Condensation

The transition from gas to liquid

Atomic absorption spectrum

The unique spectrum (to each element)of light absorbed when an atom's electrons are excited to higher energy levels.

Standard free energy

The value of deltaG as calculated under standard conditions.

Raoult's Law

The vapor pressure of one component above a solution is proportional to the mole fraction of that component in the solution. P_A = X_A * P_total

Collision theory (of chemical kinetics)

Theory stating that the rate of a reaction is directly proportional to the number of collisions per second that take place between reactants.

Isoelectronic

Two different elements that share the same electron configuration (e.g., potassium cation and argon)

Molecule

Two or more atoms joined by covalent bonds.

Dipole-dipole interactions

Type of intermolecular force in which opposite poles of neighboring dipole molecules are drawn together; similar to london dispersion, only longer in duration.

Low pressure and high temperature

Under what conditions is the ideal gas law most correct?

At high temperatures

Under what conditions will a reaction with a positive entropy and a positive enthalpy be spontaneous?

Hydrogen bonding

Very strong intermolecular force where a hydrogen covalently bonded to a nitrogen, oxygen, or fluorine, is attracted to another nitrogen, oxygen, or fluorine.

s, p, d, f orbitals

What are the first four subshells, corresponding to l = 0, 1, 2, and 3?

+1/2, -1/2

What are the possible values for m_s, the fourth quantum number?

Grams per liter

What are the typical units of density (for a gas)?

1, 760, 760

What is standard pressure in atm, mmHg, and torr?

273.15, 0

What is standard temperature in Kelvin, and Celsius?

deltaG=deltaH-TdeltaS

What is the equation that relates entropy, enthalpy, temperature, and Gibbs free energy?

deltaG = -nFE

What is the equation that relates free energy and standard potential?

q=mcdeltaT

What is the formula for calculating heat absorbed or released by a process?

deltaG = -RTlnK_eq

What is the formula relating the equilibrium constant and the change in Gibbs' free energy of a reaction?

Balances charge between electrochemical cells

What is the function of a salt bridge?

Pyramidal

What is the geometric arrangement of NH3?

Zero

What is the oxidation number of free elements?

3rd order

What is the reaction order of the following rate law: rate = k[A][B]^2?

nFE = RTln(K_eq)

What is the relationship between EMF and K_eq?

Bi-lobed/dumbbell shaped

What is the shape of a p orbital?

Spherical

What is the shape of the s orbital?

22.4 L

What is the volume of 1 mole of gas at STP?

Le Chatelier's Principle

When a system in equilibrium is subjected to a stressor, the reaction will shift towards producing either more reactants or more products in order to regain equilibrium.

Equilibrium

When does a system reach maximum entropy?

Forward

Which reaction will be favored in the following equilibrium if temperature is decreased: N_2(g) + 3H_2(g) <-> 2NH_3 ?

6s

Which subshell will fill first: 6s or 4f?

Polar covalent bond

Which type of bond forms between atoms with small difference in electronegativity (0.4-1.7)?

Nonpolar covalent bond

Which type of bond forms between atoms with the same electronegativities?

Ionic

Which type of bond forms between two atoms with differences in electronegativities greater than 1.7.

Galvanic cell

Which type of electrochemical cell generates energy?

frequency factor

a measure of how often molecules in a certain reaction collide (represented by A in the arrhenius equation)

1) zero-order reaction 2) temperature and the addition of a catalyst

a reaction in which the rate of formation of product C is independent of reactant concentrations (exponents add up to zero); what affects its rate?

first-order reaction

a reaction in which the rate of product formation is directly proportional to the concentration of one reactant (ex. radioactive decay)

second-order reaction

a reaction in which the rate of product formation is proportional to either the concentrations of two reactants or to the square of the concentration of a single reactant (exponents add to 2)

standard state

a reference form of a substance at a chosen temperature used to make comparisons with

orbital

a region of space around the nucleus for which electrons occupy and rapidly move in

neutralization reactions

a type of double-replacement reaction in which an acid reacts with a base to produce a salt (and usually water)

the reaction will push in the direction that produces fewer moles of gas (and vice versa)

according to le Chatlier's principle, what happens when a system's pressure increases?

the reaction will push in the direction determined by enthalpy (endothermic = heat functions as a reactant, exothermic = heat functions as a product)

according to le Chatlier's principle, what happens when a system's temperature increases?

excited state

an atom in this is in a higher energy level, in which at least one electron has moved to a subshell of higher than normal energy

ground state

an atom in this is in the lowest energy, in which all electrons are in the lowest possible orbitals

almost never, they must be determined experimentally and often not the same

are the values of x and y in a rate law the same as the stoichiometric coefficients?

arrhenius equation

collision theory equation that shows the effect of temperature on the rate constant (which increases with increase in temperature)

Freezing-point depession

deltaT_f = K_f m

oxidation state

different possible charged forms; many transition elements adopt many of these, which permits them to form ionic compounds

more bonds decreases bond length because two atoms are pulled closer together

does bond length increase or decrease with each new bond? why?

molecular formula

exact number of atoms of each element in the compound and is a multiple of the empirical formula

chalcogen

group 16 elements; important for normal biological functions; high concentrations are toxic and damaging, especially the heavier ones

make one reactant concentration constant and see how the other reaction affects the product formed; repeat with the other reactant though with different trials (ex. if doubling [B] results in quadrupling the rate, then you know that the exponent of [B] is four)

how are reaction rates experimentally measured?

they both have the same equation, but their values can be different based on the concentrations involved (equilibrium quotient uses concentrations at equilibrium, whereas reaction quotient uses them at a certain time)

how are the reaction quotient and equilibrium quotient similar?

through heat or other energy forms (ex. radiation)

how can atoms be excited into a higher energy level?

by summing the exponents of associated with each reaction

how do you determine the overall rate for a reaction?

polar solvents are preferred because their molecular dipole tends to polarize reactant bonds, lengthening and weakening them, permitting the reaction to occur faster

in many reactions, is a polar or nonpolar solvent generally preferred to increase reaction rate? why?

oxyanion

polyatomic anions containing oxygen; suffixes (less oxygen is ite, more oxygen is ate); prefixes (less oxygen is hypo, more oxygen is per)

third law of thermodynamics

pure elements or compounds in their solid forms at absolute zero have a zero entropy value (absolute zero is unobtainable, so this is just a theory)

empirical formula

simplest whole-number ratio of elements

line spectrum

spectrum of light that exists because each line on the emission spectrum corresponds to a specific electron transition

law of mass action

states that a system at equilibrium at constant temperature can be represented by equilibrium expression

zeroth law of thermodynamics

states that heat flows from hot to cold; also if Ta=Tb, Tb=Tc, then Ta=Tc (communicative property in math)

first law of thermodyanimcs

states that the change in total internal energy of a system is equal to the contributions of heat and work

n+l rule

states that the lower the sum of values of the first and second quantum number, the lower the energy of the subshell (helps to rank subshells by increasing energy)

second law of thermodynamics

states that things like to be in a state of higher entropy and disorder; a reaction must increase the entropy of the universe in order to proceed

standard enthalpy of formation

the change in enthalpy for a reaction that creates one mole of that compound from its raw elements in their standard states (deltaHformation)

bond energy

the energy required to break a bond; increases in proportion with number of pairs of shared electrons

bond order

the number of shared electron pairs between two atoms

pi bond

type of bond in which two parallel electron cloud densities exist and prevent free rotation around axes

sigma bond

type of bond that allows for free rotation around axes due to lower electron density between atomic orbitals

toward product (greater concentration of reactant to product)

what direction will a reaction run in when Q<Keq?

l=0 is s; l=1 is p; l=2 is d; and l=3 is f

what do the letters designate in electron configurations? (s,p,d,f)

absorb light, higher potential, excited, and distant (from the nucleus)

what four characteristics do electrons jumping from a lower energy level to a higher energy level exhibit? (AHED)

it emits a discrete amount of energy in the form of photons (Energy=hf)

what happens when an atom reverts back to ground state?

homogenous catalysis occurs when the catalyst is in the same phase as the reactants, whereas heterogeneous catalysis occurs when the catalyst is in a distinct phase

what is the difference between homogenous and heterogenous catalysis?

1) 2n^2 2) 4l+2

what is the maximum number of electrons within a shell? within a subshell?

enthalpy value of 0kj/mol

what is the standard enthalpy value for ideal gases?

one electron from the 4s subshell moves to the 3d subshell to half-fill and fully fill the d subshell respectively

what is unique about chromium's and copper's electron configurations?

reactant concentrations make up the rate law, but product concentrations do not play any role

what role do product and reactant concentrations play in the rate law?

pure solids and liquids (they are not compounds)

what type of substances are excluded from the equilibrium constant expression?

formula weight measures a weight based on the empirical formula, whereas molecular weight measures a weight based on the molecular formula

what's the difference between formula weight and molecular weight?