In chemistry an arsenite is a chemical compound containing an arsenic oxoanion where arsenic has oxidation state +3. Examples of arsenites include sodium arsenite which contains a polymeric linear anion, [AsO₂⁻]_n, and silver arsenite, Ag₃AsO₃, which contains the trigonal, AsO₃³⁻ anion. The arsenite ion is sometimes called ortho-arsenite.