Fermium (Fm)
Isotopes of Fermium
| Isotope | Atomic Mass | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
| Fm-251 | 251.08157 | 5.30 hours | EC to Es-251; α to Cf-247 |
9/2 | No data available |
| Fm-252 | 252.08246 | 1.058 days | α to Cf-248; SF | 0 | No data available |
| Fm-253 | 253.08517 | 3 days | EC to Es-253; α to Cf-249 |
1/2 | No data available |
| Fm-254 | 254.08685 | 3.24 hours | α to Cf-250; SF | 0 | No data available |
| Fm-255 | 255.08995 | 20.10 hours | α to Cf-251; SF | 7/2 | No data available |
| Fm-256 | 256.09177 | 2.63 hours | α to Cf-252; SF | 0 | No data available |
| Fm-257 | 257.095099 | 100.50 days | α to Cf-253; SF | 9/2 | No data available |
Fermium is a radioactive rare earth metal, discovered in 1952 by workers at Argonne and Los Alamos National Laboratories and by Albert Ghiorso and colleagues at the University of California - Berkeley, USA. It was identified in the radioactive debris from a thermonuclear explosion in the Pacific. The longest living isotope is is Fermium-257, with a half-life of 80 days. Fermium takes its name from that of Enrico Fermi, a pioneer in nuclear physics.
Because of the small amounts of produced fermium, as well as the relatively short half-lives of its isotopes, there are no current uses for fermium outside of basic scientific research.
Properties of Fermium
| Name | Fermium |
| Symbol | Fm |
| Atomic number | 100 |
| Atomic weight | [257] |
| Standard state | Presumably a solid at 298 °K |
| CAS Registry ID | 7440-72-4 |
| Group in periodic table | N/A |
| Group name | Actinoid |
| Period in periodic table | 7 (Actinoid) |
| Block in periodic table | f-block |
| Color | Unknown, but probably metallic and silvery white or grey in appearance |
| Classification | Metallic |
| Melting point | About 1800 °K [or 1527 °C or 2781 °F] |
| Boiling point | No data available |
| Electronegativity | 1.3 |
| Electron configuration | [Rn]5f127s2 |
