This is copied from an old answer, and attempts to explain the difference between "oxides", "peroxides", and "superoxides"....
Most oxygen containing compounds are OXIDES....i.e. they feature oxygen in its stable stackrel(-II)O oxidation state. Water, certainly features oxygen with this designation....
Now hydrogen peroxide is HO-OH, and it clearly contains an O-O bond. Because our definition of oxidation number is "the charge left on the central atom when all the bonding pairs" "of electrons are BROKEN, with the charge assigned" "to the most electronegative atom," this exercise results in the sharing of the electrons (because the oxygen atoms have equal electronegativity):
i.e. HO-OHrarr2xxdotOH
(dotOH is the so-called hydroperoxyl radical). The oxygen in hydrogen peroxide has a formal oxidation of -I.
And when we write peroxide salts, i.e. sodium peroxide, we use a formula of Na_2O_2; i.e. a salt of ""^(-)O-O^-.
And for "superoxides", to continue the formalism, we write O_2^-, that is a mixed oxidation state dioxide of O^(0) and O^(-), to give an average oxidation number of O^(-1/2). In very old literature, this goes by the label "hyperoxide".
