Fermium · Fm Fermium
artificially synthesizes actinides, mainly used for nuclear structure research.
- atomic number / Atomic number
- 100
- atomic weight / Atomic mass
- 257.09511 u
- Family/Group
- Actinium series (independent row)
- Period · Block / Period · Block
- 7 · f
- Category / Category
- Actinium series · Actinide
- State / State
- solid state
- Electron configuration
- [Rn] 5f12 7s2
- Oxidation states / Oxidation states
- +3
- Electronegativity / Electronegativity
- 1.3（Pauling）
- Density / Density
- not included
- Melting point / Melting point
- 1800 K
- Boiling point / Boiling point
- not included
- Atomic radius / Atomic radius
- not included
- First ionization energy
- 6.50 eV
- Discovery year / Discovery
- 1952
attribute description and data source
properties taken from PubChem periodic table snapshot (2026-10-04). Atomic weights may be reference values or representative isotope masses and cannot be considered exact constants for all samples; density, phase transition points, and phase states depend on temperature, pressure, and allotropes. The solidification of helium requires pressure. Some properties of radioactive and superheavy elements are predicted values, and missing items are marked as not included. Please check the original source and experimental conditions for precise calculations.