A compound containing the hydroxide ion (OH⁻) and having the general formula M(OH)_n, where M represents a metal. Hydroxides are a subset of compounds containing the hydroxyl group (–OH) and range in chemical character from strongly basic, to amphoteric (having both acidic and basic characteristics), to essentially acidic. The hydroxide ion has a closed-shell electronic structure with a singlet ground state (¹Σ⁺).