← Periodic Table
100
f🧱
Fm
257.0000

Fermium

Actinide

Atomic Properties

Atomic Number
100
Atomic Mass
257.0000 u
Electron Configuration
[Rn] 5f12 7s2
Electronegativity
1.30
Block
f-block
Group
Period
7

🌡 Physical Properties

Phase (STP)
solid
Melting Point
1800.00 K
Boiling Point
Density
9.7000 g/cm³

About Fermium

Named after Enrico Fermi; discovered in hydrogen bomb debris.

🔬 Isotopes of Fermium

Fermium has 0 naturally occurring isotopes, plus 1 notable radioactive isotope.

IsotopeMass NumberAtomic Mass (u)AbundanceType
257Fm257257.0951061Radioactive

Data source: NIH PubChem (aggregated from IUPAC, NIST)