Fermium
Synthetic actinide element discovered in hydrogen bomb fallout.
It is an actinide and one of the heaviest elements that can be formed by neutron bombardment of lighter elements, but it cannot be prepared in macroscopic quantities—only microscopic amounts (picograms or less) are possible. Pure fermium metal has not been prepared yet.
- symbol
- Fm
- discovery_event
- Ivy Mike nuclear test
- oxidation_states
- +3 (preponderant), +2 (accessible)
- known_isotopes
- 20
Lore & Background
The discovery of fermium required more material, as the yield was expected to be at least an order of magnitude lower than that of element 99, so contaminated coral from the Enewetak atoll was shipped to Berkeley for processing. About two months after the test, a new component was isolated emitting high-energy α-particles (7.1 MeV) with a half-life of about a day, quickly identified as 255Fm.
Reader's Guide
Fermium holds significance as the heaviest element that can be formed by neutron bombardment of lighter elements and the last element that can be prepared in macroscopic quantities, though pure fermium metal has not been prepared. Its discovery in the debris of the first hydrogen bomb test demonstrated the power of neutron capture in nuclear explosions to create new elements, advancing understanding of nuclear physics. The element's chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts produced and all its isotopes having relatively short half-lives, there are currently no uses for fermium outside basic scientific research. The discovery was initially kept secret on U.S.
Did You Know?
- Fermium is produced only in microscopic quantities (picograms or less); einsteinium (element 99) is the heaviest element that can be prepared in macroscopic (milligram) amounts.
Frequently Asked Questions
Who is Fermium named after and why?
The element honors Enrico Fermi, the Italian-American physicist who oversaw the first self-sustaining nuclear chain reaction and laid much of the groundwork for modern nuclear physics. Following the actinide naming tradition, the new element was given his name to recognize that contribution.
Can anyone actually see or handle a piece of Fermium?
No—only trace, microscopic amounts (picograms or less) have ever been produced, far below the threshold for a visible metal sample. Pure fermium metal has therefore never been prepared, and all chemical work is done on dissolved, ultra-dilute solutions.
More in Periodic Table & Elements 1-21
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record