Tantalum, 73Ta |
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| Pronunciation | (TAN-təl-əm) |
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| Appearance | gray blue |
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| Atomic number (Z) | 73 |
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| Group | group 5 |
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| Period | period 6 |
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| Block | d-block |
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| Electron configuration | [Xe] 4f14 5d3 6s2 |
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| Electrons per shell | 2, 8, 18, 32, 11, 2 |
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| Phase at STP | solid |
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| Melting point | 3290 K (3017 °C, 5463 °F) |
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| Boiling point | 5731 K (5458 °C, 9856 °F) |
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| Density (at 20° C) | 16.678 g/cm3 |
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| when liquid (at m.p.) | 15 g/cm3 |
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| Heat of fusion | 36.57 kJ/mol |
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| Heat of vaporization | 753 kJ/mol |
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| Molar heat capacity | 25.36 J/(mol·K) |
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Vapor pressure
| P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
| at T (K) |
3297 |
3597 |
3957 |
4395 |
4939 |
5634 |
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| Oxidation states | common: +5
−3, −1, 0, +1, +2, +3, +4 |
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| Electronegativity | Pauling scale: 1.5 |
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| Ionization energies | - 1st: 761 kJ/mol
- 2nd: 1500 kJ/mol
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| Atomic radius | empirical: 146 pm |
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| Covalent radius | 170±8 pm |
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| Spectral lines of tantalum |
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| Natural occurrence | primordial |
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| Crystal structure | body-centered cubic (bcc) (cI2) |
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| Lattice constant | a = 330.29 pm (at 20 °C) |
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| Thermal expansion | 6.3 µm/(m⋅K) (at 25 °C) |
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| Thermal conductivity | 57.5 W/(m⋅K) |
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| Electrical resistivity | 131 nΩ⋅m (at 20 °C) |
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| Magnetic ordering | paramagnetic |
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| Molar magnetic susceptibility | +154.0×10−6 cm3/mol (293 K) |
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| Young's modulus | 186 GPa |
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| Shear modulus | 69 GPa |
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| Bulk modulus | 200 GPa |
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| Speed of sound thin rod | 3400 m/s (at 20 °C) |
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| Poisson ratio | 0.34 |
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| Mohs hardness | 6.5 |
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| Vickers hardness | 870–1200 MPa |
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| Brinell hardness | 440–3430 MPa |
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| CAS Number | 7440-25-7 |
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| Naming | after Tantalus, Greek mythological figure |
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| Discovery | Anders Gustaf Ekeberg (1802) |
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| Recognized as a distinct element by | Heinrich Rose (1844) |
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Tantalum is a chemical element; it has symbol Ta and atomic number 73. It is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is highly corrosion-resistant. It is part of the refractory metals group, which are widely used as components of strong high-melting-point alloys. It is a group 5 element, along with vanadium and niobium, and it always occurs in geologic sources together with the chemically similar niobium, mainly in the mineral groups tantalite, columbite, and coltan.
The chemical inertness and very high melting point of tantalum make it valuable for laboratory and industrial equipment such as reaction vessels and vacuum furnaces. It is used in tantalum capacitors for electronic equipment such as computers. It is being investigated for use as a material for high-quality superconducting resonators in quantum processors.