Iron forms bivalent and trivalent combination with oxygen. The phenomenon of oxidation of iron is called rust.
Ferrous oxide, FeO (II), is obtained by direct burning iron. It is stable only at temperatures above 833 K (560oC) and black.
Ferric oxide, Fe2O3 (III), also known as hematite, a mineral brown is produced by oxidation of iron when there is a surplus of oxygen. He is the main source for obtaining iron.
Ferric-ferrous oxide, Fe3O4 (II, III), also known as magnetite, is natural material with the best magnetic properties.
Although these oxide coatings formed on the surface of parts, and porosity of these layers is such that objects of iron rust atmospheric effects constantly exposed to their complete destruction.
Ferric oxide is opaque to ultraviolet and infrared radiation, which finds applications in property windows thermo-absorbents manufacture.
In combination with carbon, iron can form solid solutions of iron carbide Fe 3 (also called cementite). Depending on temperature and carbon content, are solid solutions ferrite, austenite and ferrite δ.
Penta-carbon iron, Fe (CO) 5 is obtained by reacting under pressure, iron with carbon monoxide. The decomposition of carbonyl iron to achieve a purity of 97.5%. It also is used to obtain many of the iron compounds used in organic synthesis.