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Niobium |
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Pronunciation | (ny-OH-bee-əm) |
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Appearance | gray metallic, bluish when oxidized |
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Standard atomic weight Ar, std(Nb) | 7001929063700000000♠92.90637(1)[1] |
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Niobium in the periodic cairt |
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Atomic nummer (Z) | 41 |
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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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Element category | Transeetion metal |
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Electron confeeguration | [Kr] 4d4 5s1 |
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Electrons per shell | 2, 8, 18, 12, 1 |
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Pheesical properties |
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Phase at STP | solid |
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Meltin pynt | 2750 K (2477 °C, 4491 °F) |
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Bylin pynt | 5017 K (4744 °C, 8571 °F) |
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Density (near r.t.) | 8.57 g/cm3 |
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Heat o fusion | 30 kJ/mol |
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Heat o vapourisation | 689.9 kJ/mol |
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Molar heat capacity | 24.60 J/(mol·K) |
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Vapour pressur
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
2942 |
3207 |
3524 |
3910 |
4393 |
5013 |
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Atomic properties |
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Oxidation states | −3, −1, +1, +2, +3, +4, +5 (a mildly acidic oxide) |
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Electronegativity | Pauling scale: 1.6 |
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Ionisation 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 o niobium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | cubic bouk-centred |
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Speed o soond thin rod | 3480 m/s (at 20 °C) |
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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 orderin | 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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Poisson ratio | 0.40 |
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Mohs haurdness | 6.0 |
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Vickers haurdness | 870–1320 MPa |
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Brinell haurdness | 735–2450 MPa |
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CAS Nummer | 7440-03-1 |
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History |
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Namin | after Niobe in Greek meethologie, dochter o Tantalus (tantalum) |
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Diskivery | Charles Hatchett (1801) |
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First isolation | Christian Wilhelm Blomstrand (1864) |
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Recognised as a distinct element bi | Heinrich Rose (1844) |
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Main isotopes o niobium |
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Isotope |
Abundance |
Hauf-life (t1/2) |
Decay mode |
Product |
90Nb |
syn |
15 h |
β+ |
90Zr |
91Nb |
syn |
680 y |
ε |
91Zr |
91mNb |
syn |
61 d |
IT |
91Nb |
92m1Nb |
syn |
10 d |
ε |
92Zr |
γ |
– |
92Nb |
trace |
3.47×107 y |
ε |
92Zr |
γ |
– |
93Nb |
100% |
stable |
93mNb |
syn |
16 y |
IT |
93Nb |
94Nb |
trace |
20.3×103 y |
β− |
94Mo |
γ |
– |
95Nb |
syn |
35 d |
β− |
95Mo |
γ |
– |
95mNb |
syn |
4 d |
IT |
95Nb |
96Nb |
syn |
24 h |
β− |
96Mo |
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| references |