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Mole	6.022 x 10^23 particles; the chemist's counting unit		tp-ap-chemistry
Avogadro's number	6.022 x 10^23 per mole		tp-ap-chemistry
Molar mass	Mass in grams of one mole of a substance		tp-ap-chemistry
Empirical formula	The simplest whole-number ratio of atoms		tp-ap-chemistry
Molecular formula	The actual number of each atom in a molecule		tp-ap-chemistry
Percent composition	Mass percent of each element in a compound		tp-ap-chemistry
Limiting reactant	The reactant that runs out first and caps the product		tp-ap-chemistry
Theoretical yield	The maximum product predicted by stoichiometry		tp-ap-chemistry
Percent yield	(actual yield / theoretical yield) x 100		tp-ap-chemistry
Molarity	Moles of solute per liter of solution		tp-ap-chemistry
Dilution equation	M1V1 = M2V2		tp-ap-chemistry
Isotope	Atoms of one element with different numbers of neutrons		tp-ap-chemistry
Average atomic mass	Weighted average of an element's isotopes		tp-ap-chemistry
Mass spectrometry	Measures isotope masses and abundances		tp-ap-chemistry
Photoelectron spectroscopy	Measures energies needed to remove electrons from atoms		tp-ap-chemistry
Electron configuration	Arrangement of electrons in orbitals		tp-ap-chemistry
Aufbau principle	Fill lowest-energy orbitals first		tp-ap-chemistry
Pauli exclusion principle	No two electrons in an atom share all four quantum numbers		tp-ap-chemistry
Hund's rule	Fill degenerate orbitals singly before pairing		tp-ap-chemistry
Valence electrons	Outer-shell electrons involved in bonding		tp-ap-chemistry
Effective nuclear charge	Net pull felt by outer electrons		tp-ap-chemistry
Atomic radius trend	Decreases across a period, increases down a group		tp-ap-chemistry
Ionization energy trend	Generally increases across a period, decreases down a group		tp-ap-chemistry
Electronegativity	An atom's pull on shared electrons in a bond		tp-ap-chemistry
Coulomb's law	Force depends on charges and decreases with distance squared		tp-ap-chemistry
Ionic bond	Attraction between oppositely charged ions		tp-ap-chemistry
Covalent bond	A shared pair of electrons		tp-ap-chemistry
Metallic bond	Positive ions in a sea of delocalized electrons		tp-ap-chemistry
Lattice energy	Energy released when gaseous ions form an ionic solid		tp-ap-chemistry
Bond order	Number of bonding pairs between two atoms		tp-ap-chemistry
Bond length trend	Higher bond order means shorter, stronger bonds		tp-ap-chemistry
Lewis structure	A diagram of valence electrons and bonds		tp-ap-chemistry
Formal charge	Valence electrons minus nonbonding electrons minus half the bonding electrons		tp-ap-chemistry
Resonance	Multiple valid Lewis structures for one species		tp-ap-chemistry
VSEPR theory	Electron groups arrange to minimize repulsion		tp-ap-chemistry
Linear geometry	Two electron groups; 180 degrees		tp-ap-chemistry
Trigonal planar	Three electron groups; 120 degrees		tp-ap-chemistry
Tetrahedral	Four electron groups; 109.5 degrees		tp-ap-chemistry
Hybridization sp3	Four electron groups, tetrahedral		tp-ap-chemistry
Sigma bond	Head-on overlap of orbitals		tp-ap-chemistry
Pi bond	Side-by-side overlap of p orbitals		tp-ap-chemistry
Polar bond	A bond with unequal sharing		tp-ap-chemistry
London dispersion forces	Weak attractions from temporary dipoles; present in all molecules		tp-ap-chemistry
Dipole-dipole force	Attraction between polar molecules		tp-ap-chemistry
Hydrogen bonding	Strong dipole attraction involving H bonded to N, O or F		tp-ap-chemistry
Ideal gas law	PV = nRT		tp-ap-chemistry
Combined gas law	P1V1/T1 = P2V2/T2		tp-ap-chemistry
Dalton's law	Total pressure is the sum of partial pressures		tp-ap-chemistry
Kinetic molecular theory	Gas particles move randomly with energy proportional to temperature		tp-ap-chemistry
Graham's law	Lighter gases effuse faster		tp-ap-chemistry
Real gas deviation	Gases act least ideally at high pressure and low temperature		tp-ap-chemistry
Solute	The substance dissolved		tp-ap-chemistry
Solvent	The substance doing the dissolving		tp-ap-chemistry
Electrolyte	A substance that forms ions in water and conducts		tp-ap-chemistry
Net ionic equation	Shows only the species that change, omitting spectators		tp-ap-chemistry
Spectator ion	An ion unchanged by a reaction		tp-ap-chemistry
Precipitate	An insoluble solid formed in solution		tp-ap-chemistry
Beer-Lambert law	Absorbance is proportional to concentration: A = abc		tp-ap-chemistry
Oxidation	Loss of electrons		tp-ap-chemistry
Reduction	Gain of electrons		tp-ap-chemistry
Oxidizing agent	The species that is reduced		tp-ap-chemistry
Reducing agent	The species that is oxidized		tp-ap-chemistry
Rate law	Equation relating reaction rate to concentrations		tp-ap-chemistry
Reaction order	The exponent of a reactant in the rate law		tp-ap-chemistry
Rate constant	The proportionality constant k in the rate law		tp-ap-chemistry
First-order half-life	ln 2 / k; independent of concentration		tp-ap-chemistry
Collision theory	Reactions need collisions with enough energy and proper orientation		tp-ap-chemistry
Activation energy	Minimum energy for a successful collision		tp-ap-chemistry
Catalyst	Speeds a reaction by giving a lower-energy path; not consumed		tp-ap-chemistry
Rate-determining step	The slowest step in a mechanism		tp-ap-chemistry
Reaction intermediate	A species made then used up within a mechanism		tp-ap-chemistry
Arrhenius equation	Relates rate constant to temperature and activation energy		tp-ap-chemistry
Endothermic	Absorbs heat; positive delta H		tp-ap-chemistry
Exothermic	Releases heat; negative delta H		tp-ap-chemistry
Specific heat	Energy needed to raise 1 g of a substance by 1 degree C		tp-ap-chemistry
Calorimetry	Measuring heat flow, q = mc delta T		tp-ap-chemistry
Enthalpy of formation	Heat change when 1 mol forms from elements in standard states		tp-ap-chemistry
Hess's law	Total enthalpy change is the sum of steps		tp-ap-chemistry
Bond enthalpy	Energy needed to break a bond		tp-ap-chemistry
Entropy	A measure of disorder or energy dispersal		tp-ap-chemistry
Gibbs free energy	Delta G = delta H - T delta S; negative means spontaneous		tp-ap-chemistry
Standard state	Reference conditions for thermodynamic data, 1 bar		tp-ap-chemistry
Equilibrium	Forward and reverse rates are equal		tp-ap-chemistry
Equilibrium constant K	Ratio of products to reactants at equilibrium		tp-ap-chemistry
Reaction quotient Q	Same ratio at any moment; compare with K to predict direction		tp-ap-chemistry
Le Chatelier's principle	A system at equilibrium shifts to counteract a stress		tp-ap-chemistry
Ksp	Solubility product constant for a slightly soluble salt		tp-ap-chemistry
Common ion effect	A shared ion lowers solubility		tp-ap-chemistry
Arrhenius acid	Produces H+ in water		tp-ap-chemistry
Bronsted-Lowry acid	A proton donor		tp-ap-chemistry
Lewis acid	An electron pair acceptor		tp-ap-chemistry
Conjugate acid-base pair	Two species differing by one proton		tp-ap-chemistry
pH	Negative log of hydrogen ion concentration		tp-ap-chemistry
Kw	Ion product of water, 1.0 x 10^-14 at 25 degrees C		tp-ap-chemistry
Strong acid	Dissociates completely in water		tp-ap-chemistry
Buffer	A solution that resists pH change; weak acid plus its conjugate base		tp-ap-chemistry
Henderson-Hasselbalch equation	pH = pKa + log([A-]/[HA])		tp-ap-chemistry
Titration equivalence point	Moles of acid equal moles of base		tp-ap-chemistry
Indicator	A dye that changes color near the endpoint		tp-ap-chemistry
Electrochemical cell	Converts chemical energy to electrical energy or the reverse		tp-ap-chemistry
Anode	Electrode where oxidation occurs		tp-ap-chemistry
Cathode	Electrode where reduction occurs		tp-ap-chemistry
Standard cell potential	E-cell = E-cathode minus E-anode		tp-ap-chemistry
Salt bridge	Allows ion flow to keep solutions neutral		tp-ap-chemistry
Electrolysis	Using electricity to drive a nonspontaneous reaction		tp-ap-chemistry
Faraday's constant	About 96,485 coulombs per mole of electrons		tp-ap-chemistry