Oxidation states

Oxidation states are typically represented by integers which may be positive, zero, or negative. In some cases, the average oxidation state of an element is a fraction, such as ⁠8/3⁠ for iron in magnetiteFe₃O₄ (see below). The highest known oxidation state is +9, displayed by iridium in the tetroxoiridium(IX) cation (IrO₄). An even higher +10 is predicted to be possible for platinum in tetroxoplatinum(X), PtO₄. The lowest oxidation state is −5, as for boron in Al₃BC and gallium in pentamagnesium digallide (Mg₅Ga₂).