Actinium vs Berkelium

PropertyAc ActiniumBk Berkelium
Atomic number8997
SymbolAcBk
NameActiniumBerkelium
Categoryactinideactinide
Standard Atomic Weight227 u247 u
Period77
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Rn]7s26d1[Rn]7s25f9
Oxidation states[3][2, 3, 4, 5]
Electronegativity (Pauling)1.11.3
Electron affinity0.35 eV-0.5 eV
Density1.007000e+4 kg/m³1.400000e+4 kg/m³
Melting point1050.85 °C1049.85 °C
Boiling point3197.85 °C-273.15 °C
Discovery year18991949