Peroxide
= Peroxide
A <peroxide> contains an oxygen-oxygen unit, formally $\mathrm{O_2^{2-}}$ in an ionic description or an O-O single bond in compounds such as <hydrogen peroxide>. The oxygen oxidation state differs from that in an ordinary oxide.
Cleavage or transfer involving the oxygen-oxygen bond contributes to characteristic redox and radical chemistry. A peroxide is therefore not defined merely by having two oxygen atoms anywhere in its formula.