Neptunium vs Rutherfordium

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PropertyNp NeptuniumRf Rutherfordium
Atomic number93104
SymbolNpRf
NameNeptuniumRutherfordium
Categoryactinidetransition-metal
Standard Atomic Weight237 u263 u
Period77
GroupN/A4
Blockss
Phase at STPsolidsolid
Electron configuration[Rn]7s25f46d1[Rn]7s25f146d2
Oxidation states[2, 3, 4, 5, 6, 7][3, 4]
Electronegativity (Pauling)1.36N/A
Electron affinity0.48 eV0.65 eV
Density2.025000e+4 kg/m³2.330000e+4 kg/m³
Melting point643.85 °C2126.85 °C
Boiling point3901.85 °C5526.85 °C
Discovery year19401964