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It's Elemental

The Element Fermium

[Click for Isotope Data]


100 Fm Fermium 257

Atomic Number: 100

Atomic Weight: 257

Melting Point: 1800 K (1527°C or 2781°F)

Boiling Point: Unknown

Density: Unknown

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 7

Group Number: none

Group Name: Actinide

Special Notes: Radioactive and Artificially Produced

What's in a name? Named after the scientist Enrico Fermi.

Say what? Fermium is pronounced as FER-mee-em.

History and Uses:

Fermium was discovered by a team of scientists led by Albert Ghiorso in 1952 while studying the radioactive debris produced by the detonation of the first hydrogen bomb. The isotope they discovered, fermium-255, has a half-life of about 20 hours and was produced by combining 17 neutrons with uranium-238, which then underwent eight beta decays. Today, fermium is produced though a lengthy chain of nuclear reactions that involves bombarding each isotope in the chain with neutrons and then allowing the resulting isotope to undergo beta decay.

Fermium's most stable isotope, fermium-257, has a half-life of about 100.5 days. It decays into californium-253 through alpha decay or decays through spontaneous fission.

Due to the small amounts produced and its short half-life, there are currently no uses for fermium outside of basic scientific research.

Estimated Crustal Abundance: Not Applicable

Estimated Oceanic Abundance: Not Applicable

Number of Stable Isotopes: 0 (View all isotope data)

Ionization Energy: 6.50 eV

Oxidation States: +3

Electron Shell Configuration:


2s2   2p6

3s2   3p6   3d10

4s2   4p6   4d10   4f14

5s2   5p6   5d10   5f12

6s2   6p6


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For questions about this page, please contact Carol McKisson.