Niobium
Main page |
| Other names/abbreviations: | Nb Columbium |
| Element no: | 41 |
| Element group: | 5 (IUPAC) V B (American labelling) V A (European labelling) |
| Element type: | Transition metals |
| CAS-Number: | 7440-03-1 |
| EINECS-Number: | 231-113-5 |
Physical properties
Appearance | ||
| Physical state @ 20°C: | Solid | |
| Color: | Shiny white | |
Bulk properties | ||
| Molecular weight (g/mol): | 92.90638(2) [1] | |
| Melting point (°C): | 2468 [1] | |
| Boiling point (°C): | 4758 [1] | |
| Density (g/cm3): | 8.57 [1] | |
| Molar volume (cm3): | 10.80 (20 °C) [2] | |
| Elastic properties: Youngs modulus (GPa): Rigidity modulus (GPa): Bulk modulus (GPa): Poissons ratio |
103-105 [2] 37.5 [2] 170 [2] 0.34-0.38 [2] | |
Thermodynamic properties | ||
| ΔfH°gas (kJ/mol): | 724 (monoatomic) [1] 725.9 [3] | |
| ΔfH°solid (kJ/mol): | 0.0 [3] | |
| ΔH°fusion (kJ/mol): | 30.00 [3] | |
| ΔH°vaporization (kJ/mol): | 680.2 [1] | |
| S°gas (J/K·mol): | 186.3 [3] | |
| S°solid (J/K·mol): | 36.4 [3] | |
| ΔfG°gas (kJ/mol): | 681.1 [3] | |
| Cp (gas) (J/K·mol): | 20.2 (25 °C) [3] | |
| Cp (solid) (J/K·mol): | 24.8870 (20 °C) [2]
24.60 (25 °C) [3] 25.1592 (200 °C) [2] 26.3647 (400 °C) [2] 27.1424 (600 °C) [2] 27.9590 (800 °C) [2] 28.8145 (1000 °C) [2] | |
| Coeff. of linear thermal expansion (106 K-1): | 7.3 (25 °C) [3] 7.19 (200 °C) [2] 7.39 (400 °C) [2] 7.56 (600 °C) [2] 7.72 (800 °C) [2] 7.88 (1000 °C) [2] | |
Crystal structure | ||
| Crystal type: | Body centered cubic [2] | |
Electronic properties | ||
 |
Electron configuration: | 1s2-2s2-2p6-3s2-3p6-4s2-3d10-4p6-4d4-5s1 |
| Ionic radius (Å): | Nb(V): 0.64 (6-coordinate) [1] Nb(IV): 0.68 (6-coordinate) [1] Nb(III): 0.72 (6-coordinate) [1] | |
Conductivity | ||
| Electrical resisitvity (μΩ·cm): | 14.6 (20 °C) [2] 25.00 (200 °C) [2] 36.6 (400 °C) [2] 48.1 (600 °C) [2] 59.1 (800 °C) [2] 71.3 (1000 °C) [2] | Thermal (W/m·K): | 53.7 (27 °C) [3] 56.6 (200 °C) [2] 60.7 (400 °C) [2] 65.3 (600 °C) [2] |
References
1: Greenwood,N.N., Earnshaw,A. Chemistry of the elements2nd edition (1997) Edited by Greenwood,N.N., Earnshaw,A. pp. 1-1340, Butterworth-Heinemann. Oxford. Great Britain
2: Buch,A. Pure Metals Properties. A Scientific-Technical Handbook
1st edition (1999) Edited by Buch,A. pp. 1-306, ASM International and Freund Publishing House Ltd. Ohio. USA
3: CRC Handbook of Chemistry and Physics
75th edition (1994) Edited by Lide,D.R. , CRC Press Inc. Boca Raton, USA
© Michael Pilgaard
Created: October 3, 2008