Comparison of Berkelium and Fermium

Attribute	Fermium ×	Berkelium ×
Atomic mass (u)	257.09511	247.07031
Standard state	Solid	Solid
Oxidation states	+3	+3 +4
Electron configuration	[Rn]5f¹²7s²	[Rn]7s²5f⁹
Atomic radius (van der waals) (pm)	-	244
Electronegativity (pauling scale)	1.3	1.3
Melting point (K)	1800	1323
Ionization energy (eV)	6.5	6.23
Density (g/cm³)	-	14
Atomic number	100	97
Group name	Actinide	Actinide
Symbol	Fm	Bk
Discovered (year)	1952	1949