100Fm[257]
Fermium
ActinidesHeavy, radioactive metals. Most of them are made only in laboratories.
[Rn] 5f¹² 7s²
- Atomic number
- 100
- Atomic mass
- [257]
- Protons
- 100
- Neutrons
- 157
- Electrons
- 100
- Shells
- 2, 8, 18, 32, 30, 8, 2
- State at 25 °C
- Solid
- Position
- Period 7, f-block
Proton (+)Neutron (0)Electron (−)
Discovered byAlbert Ghiorso's team, 1952Albert Ghiorso: 12 elementsGlenn T. Seaborg: 10 elementsStanley G. Thompson: 5 elements
Found in the same bomb debris as einsteinium, and named after Enrico Fermi.
Did you know?
- It is the heaviest element that can be made by adding neutrons one at a time.
- No visible sample has ever been made.
Where it's found
- Made only in laboratories, a few atoms at a time
What it's used for
- Scientific research only
Try it
There's no safe home experiment for Fermium. Explore it with the animated atom above instead.