Iron becomes rusted especially in damp air but never in a dry air, this is one of the many unique characteristics of iron. Iron is also ductile and malleable. It is found in the seventh group of the periodic table. It has four different and unique crystalline forms and completely dissolves in dilute acids. The two chemical compounds that can be found or made from iron are the bivalent iron also known as ferrous and the trivalent iron or known as ferric compounds.