ions

• atom or molecule with a net electric charge, from losing or gaining electrons
• cation (positive, e.g. Na⁺), anion (negative, e.g. Cl⁻), polyatomic ions (e.g. SO₄²⁻)
• carry electric current in solutions (salt water conducts, see dissociation)
• plasma: gas ionised enough to be dominated by free electrons and ions (stars, ionosphere)