Electrode
A conducting substance that connects an electrolyte to an external circuit.

Electrolysis
The decomposition of a substance by an electric current.

Electrolyte
An ionic substance that has high electrical conductivity.

Electromotive force
The electrical potential produced by a chemical reaction. It was abbreviated as EMF.

Electron
A light subatomic particle with negative charge; found in orbitals surrounding an atomic nucleus.

Electronegativity
A number describing the attraction of an element for electrons in a chemical bond.

Element
A substance that cannot be decomposed; each chemical element is characterized by the number of protons in the nucleus. See the periodic table and the introduction for elements.

EMF
The electrical potential produced by a chemical reaction, or electromotive force.

Endothermic
Refers to a reaction that requires heat.

Energy
The concept of motion or heat.

Enthalpy
The thermodynamic quantity measuring the heat of a substance.

Entropy
The thermodynamic quantity measuring the disorder of a substance.

Equilibrium
A balanced condition resulting from two opposing reactions.

Equilibrium constant
The ratio of concentrations of products to reactants for a reaction at chemical equilibrium.

Exothermic
Refers to a reaction that releases heat.