Neptunium is an actinide that is a silver metallic color in its natural solid state. It has radioactive properties, is chemically reactive, and it is a transuranic element. Neptunium has an atomic number of 237, a melting point of 1179 °F, and a boiling point of 7232 °F. Neptunium is not used commercial as it is rare, radioactive, and toxic. The main use for neptunium today is as a basis to create the isotope, number 238, of plutonium which is used for military and spacecraft purposes.