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|
Niobium
Chemical Properties & Compounds
| Symbol | Atomic Number | Atomic Weight | Melting Point | Boiling Point | Phase | Density | Classification |
| Nb | 41 | 92.906 | 2477 °C | 4744 °C | Solid | 8.57 g/cm3 | Metal |
|
|
|
| General |
| Name, Symbol, Number |
niobium, Nb, 41 |
| Chemical series |
transition metals |
| Group, Period, Block |
5, 5, d |
| Appearance |
gray metallic
 |
| Standard atomic weight |
92.90638(2) g·mol−1 |
| Electron configuration |
[Kr] 4d4 5s1 |
| Electrons per shell |
2, 8, 18, 12, 1 |
| Physical properties |
| Phase |
solid |
| Density (near r.t.) |
8.57 g·cm−3 |
| Melting point |
2750 K
(2477 °C, 4491 °F) |
| Boiling point |
5017 K
(4744 °C, 8571 °F) |
| Heat of fusion |
30 kJ·mol−1 |
| Heat of vaporization |
689.9 kJ·mol−1 |
| Heat capacity |
(25 °C) 24.60 J·mol−1·K−1 |
Vapor pressure
| P(Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
| at T(K) |
2942 |
3207 |
3524 |
3910 |
4393 |
5013 |
|
| Atomic properties |
| Crystal structure |
cubic body centered |
| Oxidation states |
5, 3
(mildly acidic oxide) |
| Electronegativity |
1.6 (scale Pauling) |
Ionization energies
(more) |
1st: 652.1 kJ·mol−1 |
| 2nd: 1380 kJ·mol−1 |
| 3rd: 2416 kJ·mol−1 |
| Atomic radius |
145 pm |
| Atomic radius (calc.) |
198 pm |
| Covalent radius |
137 pm |
| Miscellaneous |
| Magnetic ordering |
no data |
| Electrical resistivity |
(0 °C) 152 nΩ·m |
| Thermal conductivity |
(300 K) 53.7 W·m−1·K−1 |
| Thermal expansion |
(25 °C) 7.3 µm·m−1·K−1 |
| Speed of sound (thin rod) |
(20 °C) 3480 m/s |
| Young's modulus |
105 GPa |
| Shear modulus |
38 GPa |
| Bulk modulus |
170 GPa |
| Poisson ratio |
0.40 |
| Mohs hardness |
6.0 |
| Vickers hardness |
1320 MPa |
| Brinell hardness |
736 MPa |
| CAS registry number |
7440-03-1 |
| Selected isotopes |
|
|
| References |
|
Niobium Compounds
|
Source: Wikipedia article Niobium
|
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Chemistry Quick Facts
