Niobium vs Tantalum

PropertyNb NiobiumTa Tantalum
Atomic number4173
SymbolNbTa
NameNiobiumTantalum
Categorytransition-metaltransition-metal
Standard Atomic Weight92.90637 u180.94788 u
Period56
Group55
Blockss
Phase at STPsolidsolid
Electron configuration[Kr]5s14d4[Xe]6s24f145d3
Oxidation states[-3, -1, 0, 1, 2, 3, 4, 5][-3, -1, 0, 1, 2, 3, 4, 5]
Electronegativity (Pauling)1.61.5
Electron affinity0.893 eV0.322 eV
Density8570 kg/m³1.640000e+4 kg/m³
Melting point2476.85 °C3016.85 °C
Boiling point4743.85 °C5457.85 °C
Discovery year18011802