Fermium

Koushik 26/06/2026 19:58:09 Updated 26/06/2026 19:58:09

Property	Value
Atomic Number	100
Element	Fermium
Symbol	Fm
Atomic Mass	[257] (most stable isotope)
Number of Neutrons	157 (Fermium-257)
Number of Protons	100
Number of Electrons	100
Period	7
Group	Actinide (no fixed group number)
Phase	Solid (predicted)
Radioactive	Yes
Natural	No (synthetic element)
Metal	Yes
Nonmetal	No
Metalloid	No
Type	Actinide
Atomic Radius	~190 pm (estimated)
Electronegativity	1.30 (estimated)
First Ionization Energy	6.50 eV (estimated)
Density	~9.7 g/cm³ (estimated)
Melting Point	1527 °C (estimated)
Boiling Point	— (not well established)
Number of Isotopes	No stable isotopes (Fm-257 most notable)
Discoverer	Albert Ghiorso and team
Year	1952
Specific Heat	— (not well established)
Number of Shells	7
Number of Valence Electrons	3