Fermium

Fermium

Fermium is a synthetic element with symbol Fm and atomic number 100. It is a member of the actinide series. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared. A total of 19 isotopes are known, with 257Fm being the longest-lived one with a half-life of 100.5 days.

It was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Nobel laureate Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical of the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and its short half-life, there are currently no uses for it outside of basic scientific research. Like all synthetic elements, isotopes of fermium are extremely radioactive and are considered highly toxic.

Occurrence

Because of the short half-life of all isotopes of fermium, all primordial fermium, that is fermium that could possibly be present on the Earth during its formation, has decayed by now. Synthesis of fermium from naturally occurring actinides uranium and thorium in the Earth crust requires multiple neutron capture, which is an extremely unlikely event. Therefore, most fermium is produced on Earth in scientific laboratories, high-power nuclear reactors, or in nuclear weapons tests, and is present only within a few months from the time of the synthesis. Einsteinium and fermium did occur naturally in the natural nuclear fission reactor at Oklo, but no longer do so.

Symbol		Fm
Atomic Number		100
Atomic Weight		257.0951
Oxidation States		+3
Electronegativity, Pauling		1.3
State at RT		Solid, Metal
Melting Point, K
Boiling Point, K

Appearance and Characteristics

Harmful effects:

Fermium is harmful due to its radioactivity.

Characteristics:

• Fermium is a synthetic, highly radioactive metal and has only been produced in miniscule amounts.
• Under normal conditions, it behaves in aqueous solution as expected for a trivalent actinide ion.
• Fermium metal has not been prepared. 

Uses of Fermium

• Fermium is of scientific research interest only.