Berkelium vs Mendelevium

PropertyBk BerkeliumMd Mendelevium
Atomic number97101
SymbolBkMd
NameBerkeliumMendelevium
Categoryactinideactinide
Standard Atomic Weight247 u258 u
Period77
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Rn]7s25f9[Rn]7s25f13
Oxidation states[2, 3, 4, 5][2, 3]
Electronegativity (Pauling)1.31.3
Electron affinity-0.5 eV0.997 eV
Density1.400000e+4 kg/m³1.030000e+4 kg/m³
Melting point1049.85 °C826.85 °C
Boiling point-273.15 °C-273.15 °C
Discovery year19491955