<P> An oxide / ˈɒksaɪd / is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula . `` Oxide '' itself is the dianion of oxygen , an O atom . Metal oxides thus typically contain an anion of oxygen in the oxidation state of − 2 . Most of the Earth 's crust consists of solid oxides , the result of elements being oxidized by the oxygen in air or in water . Hydrocarbon combustion affords the two principal carbon oxides : carbon monoxide and carbon dioxide . Even materials considered pure elements often develop an oxide coating . For example , aluminium foil develops a thin skin of Al O ( called a passivation layer ) that protects the foil from further corrosion . Individual elements can often form multiple oxides , each containing different amounts of the element and oxygen . In some cases these are distinguished by specifying the number of atoms as in carbon monoxide and carbon dioxide , and in other cases by specifying the element 's oxidation number , as in iron ( II ) oxide and iron ( III ) oxide . Certain elements can form many different oxides , such as those of nitrogen . </P>
<P> An oxide / ˈɒksaɪd / is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula . `` Oxide '' itself is the dianion of oxygen , an O atom . Metal oxides thus typically contain an anion of oxygen in the oxidation state of − 2 . Most of the Earth 's crust consists of solid oxides , the result of elements being oxidized by the oxygen in air or in water . Hydrocarbon combustion affords the two principal carbon oxides : carbon monoxide and carbon dioxide . Even materials considered pure elements often develop an oxide coating . For example , aluminium foil develops a thin skin of Al O ( called a passivation layer ) that protects the foil from further corrosion . Individual elements can often form multiple oxides , each containing different amounts of the element and oxygen . In some cases these are distinguished by specifying the number of atoms as in carbon monoxide and carbon dioxide , and in other cases by specifying the element 's oxidation number , as in iron ( II ) oxide and iron ( III ) oxide . Certain elements can form many different oxides , such as those of nitrogen . </P>
what must be present for a compound to be referred to as an oxide
what must be present for a compound to be referred to as an oxide
at least one oxygen atom and one other element
at least one oxygen atom and one other element