The scientific name for rust is iron oxide, and its chemical formula is Fe2O3. The scientific name for rust as a verb, the process of rusting, is oxidation.
Iron oxide forms on the surface of iron or steel as it oxidizes, creating a coating that is red or brown. For oxidation to occur, the iron must come into contact with water and air. The water on the iron's surface combines with the carbon dioxide in air to form a weak carbonic acid, which dissolves the iron. As the iron dissolves, some of the water breaks down into hydrogen and oxygen; the newly freed oxygen bonds with the dissolved iron to form iron oxide. Chemical compounds in acid rain and seawater accelerate the process of oxidation.