Praseodymium vs Mendelevium

PropertyPr PraseodymiumMd Mendelevium
Atomic number59101
SymbolPrMd
NamePraseodymiumMendelevium
Categorylanthanideactinide
Standard Atomic Weight140.90766 u258 u
Period67
GroupN/AN/A
Blockss
Phase at STPsolidsolid
Electron configuration[Xe]6s24f3[Rn]7s25f13
Oxidation states[0, 1, 2, 3, 4, 5][2, 3]
Electronegativity (Pauling)1.131.3
Electron affinity0.962 eV0.997 eV
Density6770 kg/m³1.030000e+4 kg/m³
Melting point930.85 °C826.85 °C
Boiling point3519.85 °C-273.15 °C
Discovery year18851955