SymbolNb
Latin nameNiobium
Atomic number41
Period5
Element categoryTransition elements
Relative atomic mass92.90638
GroupV.B
Electronegativity
1.6
Oxidation numbers
3, 5
Electron configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d4 5s1
Density [g/cm3]
8.57
State
Solid
Melting point [°C]
2468
Boiling point [°C]
4742
Atomic radius [pm]
198
Covalent radius [pm]
137
Thermal conductivity [W m-1K-1]
53.7
Heat capacity [J K-1g-1]
0.265
Discovery
1801
Hardness [Mohs scale]
6.0
Vickers hardness [MPa]
1320
Brinell hardness [MPa]
736
Young's modulus [GPa]
105
Electrical conductivity [S m-1]
6.7 · 106
Shear modulus [GPa]
38
1.st ionization energy [eV]
6.7589
2.nd ionization energy [eV]
14.32
3.rd ionization energy [eV]
25.04
Stable isotopes
1
Unstable isotopes
21