Niobium (Nb)

Gray metallic, bluish when oxidized

Niobium is a soft, gray Transition that makes jet engines stronger and MRI magnets colder, and with the anomalous [Kr] 4d⁴ 5s¹ configuration, niobium is used in superconducting RF cavities for particle accelerators and in NbTi alloys for MRI magnet wire. Its critical temperature is 9.3 K.

Key metrics

Density8.57g/cm³

Melting point2,750K

Boiling point5,017K

Electronegativity1.6Pauling

Discovery

1801discovered

Discovered by: Charles Hatchett
Reactivity profile: Resistant to corrosion
Reactivity: Low
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Kr]}\; \textcolor{#22c55e}{4_{d}^{4}}\; \textcolor{#ef4444}{5_{s}^{1}}

[Kr] 4d4 5s1

Wave function

\Psi_{\text{Nb}} \approx \frac{1}{\sqrt{41!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{41}(\mathbf{r}_{41}) \right|

Probability density $|\Psi|^2$ across the Nb valence shell.

Crystal structure

Body-Centered Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number8

Atoms per cell2

Atomic packing factor0.68

Physical properties

Atomic radius: 146 pm
Ionization energy: 652 kJ/mol
Electron affinity: 86 kJ/mol
Crystal structure: Body-centered cubic (bcc)

Oxidation states

+3+5

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

2750 K5017 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

405.9nmNb IViolet80%

408.0nmNb I (violet)Violet100%

534.5nmNb I (green)Green50%

Dominant line 408.0 nmRange 406–535 nmTransitions 3