SULFIDE

also spelled Sulphide, any of three classes of chemical compounds containing the element sulfur. Inorganic sulfides are ionic compounds containing the negatively charged sulfide ion S2-; these compounds may be regarded as salts of the very weak acid hydrogen sulfide (q.v.). Several inorganic sulfides are important ores of such metals as lead, copper, and zinc. Organic sulfides, sometimes called thioethers, are compounds in which a sulfur atom is covalently bonded to two organic groups. Organic phosphines react with sulfur to form phosphine sulfides, in which a sulfur atom is linked to the phosphorus by a bond that has both covalent and ionic properties.