BSSE Chemistry 1429 flashcards
BSSE Chemistry 1429 · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Atomic number
- The number of protons in the nucleus of an atom; it defines the element and determines the number of electrons in a neutral atom.
- Isotope
- Atoms of the same element with the same number of protons but different numbers of neutrons, giving different mass numbers and often different physical properties.
- Hund's rule
- When electrons occupy degenerate orbitals, they fill singly with parallel spins first to minimize electron–electron repulsion, before pairing in the same orbital.
- Effective nuclear charge
- The net positive charge experienced by an electron, equal to the actual nuclear charge minus the shielding by other electrons; it increases across a period.
- VSEPR theory
- A model predicting molecular geometry in which electron domains around a central atom arrange to minimize repulsion; lone pairs occupy more space than bonding pairs.
- Hybridization
- The mixing of atomic orbitals to form equivalent hybrid orbitals (sp, sp², sp³) that match the observed molecular geometry and bonding.
- Hydrogen bond
- A strong dipole–dipole attraction between a hydrogen atom bonded to N, O, or F and a lone pair on a nearby electronegative atom; it raises boiling points.
- Lattice energy
- The energy released when gaseous ions form a solid ionic lattice; it increases with higher ionic charges and smaller ionic radii.
- Ideal gas law
- PV = nRT, relating pressure, volume, moles, and absolute temperature; R = 0.08206 L·atm·mol⁻¹·K⁻¹ or 8.314 J·mol⁻¹·K⁻¹.
- Dalton's law
- The total pressure of a gas mixture equals the sum of the partial pressures of its components; each gas behaves independently.
- Vapor pressure
- The pressure exerted by a vapor in equilibrium with its liquid at a given temperature; it increases with temperature and depends on intermolecular forces.
- Critical point
- The temperature and pressure above which a substance becomes a supercritical fluid and distinct liquid and gas phases no longer exist.
- Limiting reactant
- The reactant that is completely consumed first in a chemical reaction, determining the maximum amount of product that can form.
- Molarity
- The number of moles of solute per liter of solution; M = n/V, used for solution stoichiometry and dilution calculations.
- Empirical formula
- The simplest whole-number ratio of atoms in a compound; it is obtained from mass percent data and may differ from the molecular formula.
- Percent yield
- The actual yield divided by the theoretical yield, multiplied by 100; it measures the efficiency of a reaction.
- Enthalpy
- The heat content of a system at constant pressure, H = U + PV; the change ΔH equals the heat exchanged at constant pressure.
- Hess's law
- The enthalpy change of an overall reaction is the sum of the enthalpy changes of its individual steps, regardless of the reaction pathway.
- Gibbs free energy
- ΔG = ΔH − TΔS; a negative ΔG indicates a spontaneous process at constant temperature and pressure, and ΔG° = −RT ln K.
- Calorimetry
- The experimental measurement of heat exchanged in a process, using q = m·c·ΔT for solutions or q = C_cal·ΔT for a bomb calorimeter.
- Le Chatelier's principle
- When a system at equilibrium is disturbed by a change in concentration, pressure, or temperature, it shifts to counteract the disturbance and restore equilibrium.
- pH
- The negative base-10 logarithm of the hydrogen ion concentration; pH = −log[H⁺], and pH + pOH = 14 at 25 °C.
- Buffer
- A solution containing a weak acid and its conjugate base (or weak base and conjugate acid) that resists large pH changes upon addition of acid or base.
- Equilibrium constant K
- The ratio of product concentrations to reactant concentrations, each raised to its stoichiometric coefficient, at equilibrium; it is temperature dependent.
- Rate law
- An equation expressing reaction rate as a function of reactant concentrations, rate = k[A]^m[B]^n; the exponents are determined experimentally.
- Half-life
- The time required for half of a reactant to be consumed; for first-order reactions, t₁/₂ = 0.693/k and is independent of initial concentration.
- Activation energy
- The minimum energy colliding molecules must possess to react; it appears in the Arrhenius equation and is lowered by a catalyst.
- Rate-determining step
- The slowest elementary step in a reaction mechanism, which controls the overall rate of the reaction and appears in the rate law.
- Oxidation
- The loss of electrons by a substance, corresponding to an increase in oxidation number; it occurs at the anode in an electrochemical cell.
- Standard reduction potential
- The voltage of a half-reaction measured against the standard hydrogen electrode under standard conditions; more positive values indicate stronger oxidizing agents.
- Nernst equation
- E = E° − (RT/nF) ln Q, relating cell potential to standard potential and reaction quotient; at 25 °C, E = E° − (0.0592/n) log Q.
- Chiral center
- A carbon atom bonded to four different groups, giving rise to non-superimposable mirror-image isomers known as enantiomers.