Samarium - chemistry.

Samarium - chemistry. Samarium, symbol Sm, hard, brittle, lustrous metallic element. Samarium is one of the rare earth elements in the lanthanide series of the periodic table (see Periodic Law). The atomic number of samarium is 62. Samarium was discovered in 1879 by the French chemist P. E. Lecoq de Boisbaudran in the mineral samarskite. The element is named for the mineral. The metal ignites in air at about 150°C (about 302°F). Like other rare earth metals, it is found in minerals such as monazite, bastnasite, cerite, gadolinite, and samarskite. Samarium is about 40th in order of abundance of the elements in Earth's crust. The element forms chiefly trivalent compounds; the salts are pale yellow in color. Samarium oxide is used in the control rods of some nuclear reactors. Samarium melts at about 1074°C (about 1965°F), boils at about 1794°C (about 3261°F), and has a specific gravity of 7.52. The atomic weight of samarium is 150.4. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.