seaborgium (Sg) /sēbôr″gē·əm/ [Glenn T. Seaborg, American chemist and educator, 1912–1999] , a synthetic radioactive element, with a half-life of 0.9 second. Its atomic number is 106; its atomic mass is 266. It was first synthesized in 1974 by scientists working independently in the United States and Russia.
