Periodic TableAll elementsFermium
No. 100
Fm
257 u
Element · Actinide

Fermium

Fermium (镄, symbol Fm) is chemical element number 100, an Actinide in period 7 of the periodic table, with a standard atomic weight of about 257. Heaviest actinide that can be created by neutron capture. Named for Enrico Fermi.

Period 7Group —[Rn] 5f¹² 7s²

Properties

Atomic number100
SymbolFm
Atomic mass257 u
CategoryActinide
Period7
Group
Electron configuration[Rn] 5f¹² 7s²
Electronegativity1.3
Covalent radius
Density9.7 g/cm³
Melting point1800 K
Boiling point
DiscoveryGhiorso et al., 1952

Overview

Heaviest actinide that can be created by neutron capture. Named for Enrico Fermi. Fermium (symbol Fm) is chemical element number 100, sitting in period 7 of the periodic table and classed as an Actinide. As an actinide it is typically radioactive and closely tied to nuclear technology.

With 2 electrons in its outermost shell, Fermium bonds accordingly; full configuration [Rn] 5f¹² 7s², electronegativity 1.3. At room temperature it is normally a solid; it melts near 1800 K (1526.9 °C), has a density around 9.7 g/cm³.

Common applications range across Research. It is regarded as a high-hazard element, so handle it with appropriate care. It was first described by Ghiorso et al. in 1952. Browse elements of the same category in the browse view.

Electron shells

Fm100

Electrons per shell: 2 · 8 · 18 · 32 · 30 · 8 · 2

Main uses

Hazard

HighRadioactive

Compounds containing Fermium

No compounds in this knowledge base contain Fermium yet.

Data sources

Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.