Fermium

General properties
Name, symbol, number	fermium, Fm, 100
Element category	actinide
Group, period, block	n/a, 7, f
Standard atomic weight	(257)
Electron configuration	[Rn] 5f12 7s2 2, 8, 18, 32, 30, 8, 2
History
Discovery	Lawrence Berkeley National Laboratory (1952)

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.

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