AP Chemistry; Introductory Vocab Words

Activation Energy

Minimum energy needed to be added to a system for a chemical reaction to occur.

Alpha Particle

He2+; 2 protons, mass number = 4, 2+ charge; highly ionizing particle with low energy.

Anion

Negatively charged ion.

Arrhenius Acid

Donates a H+ ion.

Arrhenius Base

Donates a OH- ion.

Atom

Smallest unit of ordinary matter with the properties of a chemical element.

Atomic Mass

Average of all naturally occurring isotopes.

Atomic Number

Number of protons that defines the atom.

Beta Particle

-1 proton, mass number = 0; medium ionizing ability and medium energy.

Boiling

Phase change from a liquid to a gas.

Bronsted-Lowry Acid

Donates a proton (H+).

Bronsted-Lowry Base

Accepts a proton (H+).

Calorimetry

Method for measuring heat gained/lost by a system during a chemical reaction.

Catalyst

Lowers activation energy; not a reactant or product.

Cation

Positively charged ion.

Chemical Equilibrium

Rate of the forward reaction equals the rate of the reverse reaction.

Condensation

Phase change from a gas to a liquid.

Covalent Bond

Bond formed by sharing electrons between atoms.

Deposition

Phase change from a gas to a solid.

Dipole-Dipole

Permanent intermolecular force present in polar molecules.

Direct Relationship

Relationship where one variable changes in the same manner as another.

Dissociate

To break into ions.

Dissolve

To break into smaller pieces.

Distillation

Process of separating liquids based on boiling temperature differences.

Double Bond

Two shared pairs of electrons.

Electrolyte

Dissociates into charged particles capable of conducting electricity.

Electrolytic Cell

Redox reaction that is spontaneous.

Electronegativity

Ability of an atom to attract electrons; fluorine is the most electronegative element.

Electron Affinity

Energy released when an atom gains an electron; chlorine has the highest electron affinity.

Electron

Negatively charged particle with a charge of -1, mass ~ 0 amu, located in orbitals around the nucleus.

Empirical Formula

Lowest whole number ratio of atoms in a compound.

Molecular Formula

True formula representing the actual number of each atom in a substance.

Endothermic

Energy is gained by the system.

Evaporation

Process of removing water from an aqueous solution, leaving the solute behind.

Exothermic

Energy is released by the system.

Filtrate

Liquid that passes through filter paper.

Filtration

Process of separating a precipitate from its aqueous solution.

Formula Unit

Ionically bonded atoms.

Freezing

Phase change from a liquid to a solid.

Galvanic / Voltaic Cell

Redox reaction that is spontaneous.

Gamma Ray

0 protons, mass number = 0; low ionizing ability and high energy.

Halogen

Elements in group 17 that form halides as ions.

Hydrogen Bonding

Strong dipole-dipole interaction when H is bonded to F, O, or N.

Indirect Relationship

Relationship where one variable changes in the opposite manner to another.

Insoluble

Does not dissolve in water.

Intermediate

Species produced in one step and consumed in another.

Intermolecular Forces (IMF)

Attractive forces between molecules.

Ion

Charged particle.

Ionic Bond

Bond formed by transferring electrons from the least electronegative atom to the more electronegative atom.

Ionization Energy

Energy required to remove the outer electron.

Kinetic Energy

Energy of motion; temperature measures kinetic energy.

Limiting Reactant

Reactant that runs out first, limiting product formation.

London Dispersion Forces

Temporary IMF caused by electron movement; present in all substances.

Lone Pair

Unbonded electrons.

Mass Number

Total mass of protons and neutrons.

Melting

Phase change from a solid to a liquid.

Molar Mass

Grams per 1 mole.

Molarity

Moles of solute per liter of solution.

Molecular Formula

Actual number of moles of each atom in a compound.

Molecule

Covalently bonded atoms.

Neutron

Neutral particle with no charge, mass = 1 amu, located in the nucleus.