Fermium (Fm)
Fermium is the chemical element with atomic number 100 and symbol Fm. It is a actinoid in period 7, with a standard atomic weight of 257 u.
Key facts
- Z
- 100
- Atomic weight
- 257 u no stable isotope
- Category
- actinoid
- State at 298 K
- Unknown
- Occurrence
- synthetic, radioactive
- Discovered
- 1952
- CAS
- 7440-72-4
Measured properties
| Property | Value | Source |
|---|---|---|
| Electronegativity | 1.3 | National Center for Biotechnology Information (NIH) |
| Melting point | 1,800 K | National Center for Biotechnology Information (NIH) |
| Ionization energy 1st | 627.2 kJ/mol | National Center for Biotechnology Information (NIH) |
Electron configuration
- Noble gas notation
- [Rn] 5f¹² 7s²
- Full notation
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f¹² 6s² 6p⁶ 7s²
- Electrons per shell
- 2, 8, 18, 32, 30, 8, 2