Lanthanide, atomic number 62.
Samarium is a chemical element with symbol Sm and atomic number 62. It is a moderately hard silvery metal that readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3.
Symbol Sm. Atomic mass 150.362 u. Group 3, period 6. Electron configuration [Xe] 4f6 6s2. Electrons per shell 2, 8, 18, 24, 8, 2. State at room temperature: Solid. Melting point 1071.8 °C, boiling point 1899.8 °C. Discovered by Lecoq de Boisbaudran.
Element data from Wikipedia, CC BY-SA 3.0.