(chemistry) The hypothetical charge of an atom within a molecule.

(organic chemistry) An epoxide.

(organic chemistry) The simplest epoxide; used as a sterilizing agent and in the production of ethylene glycol.

(chemistry) the state of an atom having a particular oxidation number

(chemistry) The compound obtained by the reaction of oxygen on iron. Either iron(II) oxide (old term ferrous oxide, chemical formula FeO) or iron(III) oxide (old term ferric oxide, chemical formula Fe₂O₃). Generally known as rust when hydrated.

(inorganic chemistry) A white solid, of empirical formula B₂O₃; it is an inorganic polymer used in making glass and enamel and for synthesizing other boron compounds.

(inorganic chemistry) A yellow oxide of lead, PbO, used in the manufacture of paints and glass.

(inorganic chemistry) The simple systematic name for water, H₂O.

(chemistry) Any of a class of organic compound formed by addition of an oxygen atom to an amine - R₃N⁺-O⁻, but sometimes written R₃N=O.

(chemistry) An aminoxyl radical.