Fermium
Fermium, a radioactive, metallic chemical element. Fermium does not occur in nature; it is produced artificially in trace amounts. Some isotopes of fermium are produced in nuclear reactors by irradiating plutonium 239 with neutrons; others are produced in linear accelerators by bombarding isotopes of plutonium or uranium with carbon, oxygen, or beryllium ions. The longest-lived isotope is fermium 257, with a half-life period of about 80 days. Fermium has no commercial uses, but is important as a radioactive tracer in nuclear research.
Fermium was discovered in 1953 by a team of United States scientists headed by Albert Ghiorso while studying the debris of the first hydrogen bomb explosion. The element was named for Enrico Fermi.
Symbol: Fm. Atomic number: 100. Atomic weight of most stable isotope: 257. Fermium has 10 known isotopes, Fm-248 to Fm-257. It is a transuranium element belonging to the actinide series of the Periodic Table and has a valence of +3.