Anion

An anion (pronounced with 3 syllables, as in "an eye on") is a negatively charged ion. It is the opposite of a cation. It is so named because, during electrolysis, it migrates toward the anode. Anions consist of electronegativity nonmetals, especially oxygen, sulfur, and the halogens, often in combination with other elements. In a sodium chloride solution the Na⁺ ions are cations and the Cl^- ions are anions.