 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 . Compounds of samarium ( II ) are also known , most notably the monoxide SmO , monochalcogenides SmS , SmSe and SmTe , as well as samarium ( II ) iodide . The last compound is a common reducing agent in chemical synthesis . Samarium has no significant biological role and is only slightly toxic . 
