41NbNiobium92.90637 u
Niobium (Nb)
Niobium is a transition metal with atomic number 41, in period 5 and group 5 of the periodic table. Its atomic mass is 92.90637 u and its electron configuration is [Kr] 4d⁴ 5s¹. Solid at 25 °C.
Key facts
| Atomic number | 41 |
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| Atomic mass | 92.90637 u |
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| Category | Transition Metal |
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| Period | 5 |
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| Group | 5 |
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| Block | d |
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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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| Electronegativity (Pauling) | 1.6 |
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| Oxidation states | −3, −1, +1, +2, +3, +4, +5common in bold |
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| State at 25 °C | Solid |
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| Melting point | 2750 K2476.85 °C |
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| Boiling point | 5017 K4743.85 °C |
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| Density | 8.57 g/cm³ |
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Atomic properties
| First ionization energy | 6.759 eV |
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| Electron affinity | 86.1 kJ/mol |
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| Atomic radius | 146 pm |
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| Covalent radius | 164 pm |
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| Van der Waals radius | 207 pm |
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| Common ions | Nb⁵⁺, Nb³⁺ |
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| Protons, neutrons, electrons | 41, 52, 41 |
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Physical and thermal properties
| Molar volume | 10.83 cm³/mol |
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| Heat of fusion | 26.8 kJ/mol |
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| Heat of vaporization | 690 kJ/mol |
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| Specific heat | 265 J/(kg·K) |
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| Thermal conductivity | 54 W/(m·K) |
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| Thermal expansion | 7.3 × 10⁻⁶ K⁻¹ |
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| Mohs hardness | 6 |
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| Young’s modulus | 105 GPa |
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| Crystal structure | Body-centered cubic |
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| Magnetic type | Paramagnetic |
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Identification and history
| CAS number | 7440-03-1 |
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| Latin name | Niobium |
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| Discovered by | Charles Hatchett · 1801 |
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| Named by | --- |
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Natural isotopes
| Isotope | Mass (u) | Abundance |
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| 93Nb | 92.906373 | 100 % |
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
See Niobium in the app
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Periodic Table