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Pronunciation | (ny-OH-bee-əm) |
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Appearance | gray metallic, bluish when oxidized |
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Group | group 5 |
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Period | period 5 |
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Block | d-block |
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Electron configuration | [Kr] 4d4 5s1 |
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Electrons per shell | 2, 8, 18, 12, 1 |
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Phase at STP | solid |
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Melting point | 2750 K (2477 °C, 4491 °F) |
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Boiling point | 5017 K (4744 °C, 8571 °F) |
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Density (near r.t.) | 8.57 g/cm3 |
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Heat of fusion | 30 kJ/mol |
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Heat of vaporization | 689.9 kJ/mol |
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Molar heat capacity | 24.60 J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
2942 |
3207 |
3524 |
3910 |
4393 |
5013 |
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Oxidation states | −3, −1, 0, +1, +2, +3, +4, +5 (a mildly acidic oxide) |
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Electronegativity | Pauling scale: 1.6 |
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Ionization energies | - 1st: 652.1 kJ/mol
- 2nd: 1380 kJ/mol
- 3rd: 2416 kJ/mol
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Atomic radius | empirical: 146 pm |
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Covalent radius | 164±6 pm |
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Spectral lines of niobium |
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Natural occurrence | primordial |
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Crystal structure | body-centered cubic (bcc) |
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Thermal expansion | 7.3 µm/(m⋅K) |
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Thermal conductivity | 53.7 W/(m⋅K) |
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Electrical resistivity | 152 nΩ⋅m (at 0 °C) |
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Magnetic ordering | paramagnetic |
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Young's modulus | 105 GPa |
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Shear modulus | 38 GPa |
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Bulk modulus | 170 GPa |
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Speed of sound thin rod | 3480 m/s (at 20 °C) |
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Poisson ratio | 0.40 |
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Mohs hardness | 6.0 |
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Vickers hardness | 1320 MPa |
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Brinell hardness | 736 MPa |
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CAS Number | 7440-03-1 |
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Heinrich Rose (1844) |
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Category: Niobium | references |