Terbium vs Einsteinium

PropertyTb TerbiumEs Einsteinium
Atomic number6599
SymbolTbEs
NameTerbiumEinsteinium
Categorylanthanideactinide
Standard Atomic Weight158.92535 u252 u
Period67
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Xe]6s24f9[Rn]7s25f11
Oxidation states[0, 1, 2, 3, 4][2, 3, 4]
Electronegativity (Pauling)N/A1.3
Electron affinity1.124 eV-0.3 eV
Density8230 kg/m³8840 kg/m³
Melting point1355.85 °C859.85 °C
Boiling point3229.85 °C-273.15 °C
Discovery year18431952