Samarium, << suh MAR ee uhm >> (chemical symbol, Sm), is a chemical element and one of the lanthanide metals. Alloys of samarium and cobalt are excellent magnetic materials and have many commercial uses. Samarium has a silver color and slowly oxidizes in air. The common oxide has a pale yellow color and is rapidly soluble in most acids. Paul Emile Lecoq de Boisbaudran of France discovered samarium in 1879. The element is named after the Russian engineer Colonel V. E. Samarski.
Samarium’s atomic number (number of protons in its nucleus) is 62. Its relative atomic mass is 150.36. An element’s relative atomic mass equals its mass (amount of matter) divided by 1/12 of the mass of carbon 12, the most abundant form of carbon. Samarium’s density is 7.536 grams per cubic centimeter at 25 °C (see Density ). For information on the position of samarium on the periodic table, see the article Periodic table .
The metal melts at 1074 °C and boils at 1794 °C. Samarium is best separated from other lanthanides by ion-exchange or solvent-extraction processes.
