- Fermium (Fm) is a synthetic, silvery, radioactive metal with atomic number 100, belonging to the actinide series.
- Its electron configuration is [Rn] 5f¹² 7s², and it most commonly exhibits the +3 oxidation state, though +2 can be achieved under strongly reducing conditions. The atomic structure contains one hundred protons, typically one hundred and fifty-seven neutrons in fermium-257 (²⁵⁷Fm), and one hundred electrons arranged in seven shells.
- Fermium does not occur naturally and is produced only in minute amounts by neutron bombardment of lighter actinides, such as plutonium or curium, in high-flux nuclear reactors. The most important isotope is fermium-257 (²⁵⁷Fm), with a half-life of 100.5 days, as it is the longest-lived fermium isotope suitable for laboratory study.
- Fermium was first discovered in late 1952 by Albert Ghiorso and his research team while examining the debris from the first U.S. hydrogen bomb test, “Ivy Mike,” conducted on Enewetak Atoll. The intense neutron flux generated during the thermonuclear explosion caused multiple neutron captures and beta decays in uranium-238, eventually forming fermium isotopes. Its discovery, like that of einsteinium, was initially classified due to Cold War security concerns and was not made public until 1955. The element was named in honor of Enrico Fermi, the Italian-American physicist who was a pioneer in nuclear physics and the development of the first nuclear reactor.
- Because fermium can only be produced in nanogram to microgram quantities, it has no commercial applications. Its primary use is in scientific research, particularly in studying the properties of heavy actinides and the processes of nuclear synthesis. Fermium is also notable for marking a practical limit in neutron irradiation: beyond fermium, production of heavier elements becomes increasingly inefficient due to rapid decay and spontaneous fission.
- Chemically, fermium behaves like other trivalent actinides, forming compounds such as fermium(III) oxide (Fm₂O₃) and fermium(III) chloride (FmCl₃). In aqueous solution, the Fm³⁺ ion is stable and forms complexes with common inorganic ligands like nitrates and sulfates. The +2 oxidation state can be achieved, for instance, in fermium(II) sulfate, but it is less stable.
- Biologically, fermium has no known function and is extremely radiotoxic, emitting alpha particles and, in some isotopes, low-level gamma radiation. Handling fermium requires remote techniques, heavy shielding, and strict containment protocols to prevent radiological exposure.
- Environmentally, fermium is found only in specialized nuclear reactors or as a byproduct of thermonuclear explosions. It does not exist in nature and has a negligible environmental presence due to its rapid decay and limited production.
