Atomic Element Z = 100 • Actinide
Fermium (Fm) — Atomic Data, Electron Shells & Reactions
Fermium (symbol Fm, atomic number 100) has a standard atomic weight of 257 u and ground-state configuration [Rn] 5f12 7s2.
Atomic Number (Z)
100
IUPAC Symbol
Fm
Standard Atomic Weight
257 g/mol
Period / Group / Block
7 / f-block / f-block
Condensed Electron Config
[Rn] 5f12 7s2
Full Subshell Config
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f12 6s2 6p6 7s2
Principal Shell Occupancy
[2, 8, 18, 32, 30, 8, 2]
Pauling Electronegativity
1.3
First Ionization Energy
627 kJ/mol
Covalent Radius
167 pm
Melting Point
1800 K (1526.85 °C)
Boiling Point
—
Density
9.7 g/cm³
Oxidation States
+3
Fm (Z=100) — Valence shell highlighted in vermilion