Ions (Gr. Ion - Walking)

Ions are atoms or groups of atoms that carry an electrical charge, which can be positive (for cations) or negative (for anions).

Cations are formed when a neutral atom or molecule loses electrons. For example, the sodium cation Na+ is formed when the sodium atom loses one electron.

Anions are formed when a neutral atom or molecule gains electrons. For example, the chlorine anion Cl- is formed when a chlorine atom gains one electron.

Ions play an important role in many chemical processes. They participate in the formation of ionic bonds, charge transfer in solutions and living organisms, and catalysis of chemical reactions. The mobility of ions in solutions and melts determines their electrical conductivity.