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Fermium
Fm 100

Fermium

Fermium is a synthetic chemical element; it has symbol Fm and atomic number 100. It is an actinide and 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-257 with a half-life of 100.5 days was only made in picogram amounts in 1997. Fermium was named in honor of Enrico Fermi. It has no commercial uses.

Actinide b31fba
Atomic number 100Z
Atomic mass 257u
Valence e⁻ 2
Electron config. 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f12
Density
—
Melting point
1527°C
Crustal abundance
1e-16ppm
Annual production
—
Recycling rate
0%(Radioactive synthetic element; no recycling)

Why This Element

Fermium is the heaviest element that can be created by neutron bombardment — heavier elements (Es through Lr) require alpha particle bombardment or heavy-ion fusion. No commercial applications; Fm-252 emits neutrons from its 3% spontaneous fission decay.

Applications

Research

Applications in DepthElement & compound uses

Main Uses of the Element

Fermium is the actinide element with atomic number 100, discovered by U.S. scientists in 1952 in the radioactive debris of the first hydrogen bomb test, in the same year as einsteinium. Even its longest-lived known isotope has a half-life of only about one hundred days, the amounts that can actually be prepared are limited to the atomic scale, and it does not occur in nature at all. It therefore has no practical uses and serves only in basic research on the nuclear structure and chemical behavior of superheavy elements.

Key Compounds and Their Uses

Fermium compounds, such as fermium(III) oxide (Fm2O3), have only ever been observed in single-atom on-line chemistry studies of accelerator reaction products; they have never been isolated or weighed in macroscopic quantities, have no scale of application, and do not appear in any civilian product.

Element History

Discovered in 1952 by Albert Ghiorso's team in Ivy Mike thermonuclear fallout — fermium-255 (20.1-hour half-life) was identified alongside einsteinium. Named for Enrico Fermi, the pioneer of nuclear fission. Fm-252 (258-day half-life) is the most stable isotope. Production limited to trace amounts.

Related Elements

Ac · Actinium Th · Thorium Pa · Protactinium U · Uranium Np · Neptunium Pu · Plutonium Am · Americium Cm · Curium

Frequently Asked QuestionsLong-tail Q&A · data-driven

What is the melting point of Fermium?
1527 °C
What is the boiling point of Fermium?
0 °C
What is the density of Fermium?
0.0 g/cm³
What are the atomic number and category of Fermium?
100 · Actinide
Which ore is Fermium mainly extracted from?
None (synthetic)
What are the main uses of Fermium?
Fermium is the heaviest element that can be created by neutron bombardment — heavier elements (Es through Lr) require alpha particle bombardment or heavy-ion fusion. No commercial applications; Fm-252 emits neutrons from
Who discovered Fermium and when?
Lawrence Berkeley National Laboratory · 1952