Comparison of Niobium and Tantalum

Attribute	Tantalum ×	Niobium ×
Atomic mass (u)	180.9479	92.90637
Standard state	Solid	Solid
Oxidation states	+5	+3 +5
Electron configuration	[Xe]6s²4f¹⁴5d³	[Kr]5s¹4d⁴
Atomic radius (van der waals) (pm)	217	207
Electronegativity (pauling scale)	1.5	1.6
Electron affinity (eV)	0.322	0.893
Ionization energy (eV)	7.89	6.759
Boiling point (K)	5731	5017
Melting point (K)	3290	2750
Density (g/cm³)	16.4	8.57
Atomic number	73	41
Group name	Transition metal	Transition metal
Discovered (year)	1802	1801
Symbol	Ta	Nb