Plutonium vs Fermium

PropertyPu PlutoniumFm Fermium
Atomic number94100
SymbolPuFm
NamePlutoniumFermium
Categoryactinideactinide
Standard Atomic Weight244 u257 u
Period77
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Rn]7s25f6[Rn] 5f12 7s2
Oxidation states[2, 3, 4, 5, 6, 7, 8][2, 3]
Electronegativity (Pauling)1.281.3
Electron affinity-0.5 eV0.339 eV
Density1.984000e+4 kg/m³9700 kg/m³
Melting point639.85 °C1526.85 °C
Boiling point3227.85 °C-273.15 °C
Discovery year19411952