Discovery date : 1953
Discovered by: Albert Ghiorso and colleagues
Origin of the name: Fermium is named after the nuclear physicist Enrico Fermi.
Allotropes :
~>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.
| FACT BOX | |||
| Group | Actinides | Melting point | 1527°C, 2781°F, 1800 K |
| Period | 7 | Boiling point | Unknown |
| Block | f | Density (g cm−3) | Unknown |
| Atomic number | 100 | Relative atomic mass | [257] |
| State at 20°C | Solid | Key isotopes | 257Fm |
| Electron configuration | [Rn] 5f127s2 | CAS number | 7440-72-4 |
| ChemSpider ID | 22434 | ChemSpider is a free chemical structure database | |
Fermium was discovered in 1953 in the debris of the first thermonuclear explosion which took place on a Pacific atoll on 1 November 1952. In this a uranium-238 bomb was used to provide the heat necessary to trigger a thermonuclear explosion. The uranium-238 had been exposed to such a flux of neutrons that some of its atoms had captured several of them, thereby forming elements of atomic numbers 93 to 100, and among the last of these was an isotope of element 100, fermium-255. News of its discovery was kept secret until 1955.
Meanwhile a group at the Nobel Institute in Stockholm had independently made a few atoms of fermium by bombarding uranium-238 with oxygen nuclei and obtained fermium-250, which has a half-life of 30 minutes.