Cerium (Ce)

Cerium ([Xe]4f¹⁵d¹⁶s²) (CAS 7440-45-1) is an iron-gray, soft, ductile, and malleable metal. It is the most abundant of the rare earth elements. It is a reactive metal, rapidly oxidizing in air forming a superficial oxide coating. The metal reacts rapidly with water, readily dissolves in mineral acids and will react with most nonmetals on heating. Cerium has many uses, including as an alloying agent with iron and other metals.