AP Chemistry Review Flashcards

Vocabulary flashcards covering the core concepts of AP Chemistry, including atomic structure, bonding, intermolecular forces, kinetics, thermodynamics, and equilibrium.

Isotopes

Atoms of an element with different numbers of neutrons.

Average atomic mass

The weighted average of isotope mass and relative abundance (frequency).

Avogadro’s number

$$6.022 \times 10^{23}$$

Photoelectron spectroscopy

A technique where energy is measured in electronvolts ($eV$) to determine the binding energy and kinetic energy of ejected electrons.

Aufbau principle

The rule stating that electrons fill lowest energy subshells available first.

Pauli exclusion principle

The rule stating that two electrons in the same orbital cannot have the same spin.

Hund’s rule

The rule stating that electrons occupy empty subshells first.

Ionization energy

The energy required to remove an electron from an atom.

Electronegativity

How strongly the nucleus of an atom attracts electrons of other atoms in a bond.

Electron affinity

The energy change that occurs when an electron is added to an atom in the gas state, which is usually exothermic.

Sea of electrons model

A bonding model for metals where a positively charged core is stationary while valence electrons are very mobile.

Interstitial alloy

An alloy formed between metals of different radii.

Substitutional alloy

An alloy formed between metals of similar radii.

Sigma bond

A bond of order 1 that is the longest in length and has the least bond energy.

Pi bond

A bond found in double bonds (1 sigma, 1 pi) and triple bonds (1 sigma, 2 pi) that contributes to shorter bond length and greater bond energy.

Formal charge

The number of valence electrons minus assigned electrons ($1\,e^-$ for each shared bond); it equals 0 for neutral molecules.

Dipole-dipole forces

Intermolecular forces between polar molecules where the positive end of one is attracted to the negative end of another.

Hydrogen bonds

A strong type of dipole-dipole attraction where a positively charged hydrogen atom bonded to $F$, $O$, or $N$ is attracted to the electronegative end of another molecule.

London dispersion forces (LDF)

Weak attractions in all molecules due to random motion of electrons resulting in instantaneous polarity.

Vaporization

The process where molecules in a liquid escape intermolecular forces to transition into the gas phase without added outside energy.

Retention factor ($R_f$)

A value calculated in chromatography as the distance traveled by the solute divided by the distance traveled by the solvent front.

Effusion

The rate at which a gas escapes from a container through microscopic holes.

Beer’s law

The equation $A = abc$ stating there is a direct relationship between the concentration of a solution and its absorbance.

Intermediates

Species that are produced in a reaction mechanism but are fully consumed and do not appear in the balanced equation.

Rate determining step

The slowest elementary step in a reaction mechanism that determine the overall speed of the reaction.

Enthalpy of formation ($\Delta H_f$)

The change in energy when one mole of a compound is formed from its component pure elements under standard conditions ($25^\circ\text{C}/298\,\text{K}$).

Specific heat

The amount of heat required to raise the temperature of one gram of a substance by one degree $\text{C/K}$.

Enthalpy of fusion

The energy required to melt a solid.

Le Chatelier’s principle

The principle that if a system at equilibrium is disturbed, the system will shift to favor the side that opposes the change.

Common ion effect

When newly added ions from a separate solution affect the equilibrium of an initial solution due to a shared element.

Amphoteric

The property of a substance, such as water, that allows it to act as either an acid or a base.

Buffers

Solutions with a stable pH created by mixing large amounts of a weak acid or base with its conjugate salt.

Indicators

Weak acids that change colors in certain pH ranges due to the shift in equilibrium between protonated and deprotonated states.

Entropy ($S$)

A measure of the randomness or dispersion of a system.

Gibbs free energy ($G$)

A thermodynamic potential used to predict spontaneity; a negative $\Delta G$ indicates a favored or spontaneous reaction.

Galvanic cells

Electrochemical cells where a favored redox reaction generates a flow of current from an oxidation anode to a reduction cathode.

Electrolytic cells

Cells that use an outside source of voltage to force an unfavored redox reaction to occur.

Salt bridge

A component in an electrochemical cell that maintains electrical neutrality by allowing cations and anions to flow between chambers.