Comparison of Fermium and Mendelevium

Attribute	Mendelevium ×	Fermium ×
Atomic mass (u)	258.09843	257.09511
Standard state	Solid	Solid
Oxidation states	+2 +3	+3
Electron configuration	[Rn]7s²5f¹³	[Rn]5f¹²7s²
Ionization energy (eV)	6.58	6.5
Electronegativity (pauling scale)	1.3	1.3
Melting point (K)	1100	1800
Atomic number	101	100
Group name	Actinide	Actinide
Discovered (year)	1955	1952
Symbol	Md	Fm