Fermium vs Mendelevium

PropertyFm FermiumMd Mendelevium
Atomic number100101
SymbolFmMd
NameFermiumMendelevium
Categoryactinideactinide
Standard Atomic Weight257 u258 u
Period77
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Rn] 5f12 7s2[Rn]7s25f13
Oxidation states[2, 3][2, 3]
Electronegativity (Pauling)1.31.3
Electron affinity0.339 eV0.997 eV
Density9700 kg/m³1.030000e+4 kg/m³
Melting point1526.85 °C826.85 °C
Boiling point-273.15 °C-273.15 °C
Discovery year19521955