An oxide is a compound in which oxygen is combined with another element, usually with oxygen formally in oxidation state . Ionic metal oxides and covalent nonmetal oxides can have very different structures.
For example, magnesium oxide is a lattice solid, whereas carbon dioxide is molecular. Peroxides contain an oxygen-oxygen unit with a different oxidation-state assignment, so they should not be treated as ordinary oxides merely because they contain oxygen.
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