Tantalum is a chemical element ; it has symbol Ta and atomic number 73. Previously known as tantalium , it is named after Tantalus , a figure in Greek mythology.[7] 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 .
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Tantalum, 73 Ta Pronunciation (TAN -təl-əm ) Appearance gray blue
Atomic number (Z ) 73 Group group 5 Period period 6 Block d-block Electron configuration [ Xe ] 4f14 5d3 6s2 Electrons per shell 2, 8, 18, 32, 11, 2 Phase at STP solid Melting point 3290 K (3017 °C, 5463 °F) Boiling point 5731 K (5458 °C, 9856 °F) Density (at 20° C) 16.678 g/cm3 [3] when liquid (at m.p. ) 15 g/cm3 Heat of fusion 36.57 kJ/mol Heat of vaporization 753 kJ/mol Molar heat capacity 25.36 J/(mol·K) Vapor pressure
P (Pa)
1
10
100
1 k
10 k
100 k
at T (K)
3297
3597
3957
4395
4939
5634
Oxidation states −3, −1, 0, +1, +2, +3, +4, +5 (a mildly acidic oxide) Electronegativity Pauling scale: 1.5 Ionization energies 1st: 761 kJ/mol 2nd: 1500 kJ/mol Atomic radius empirical: 146 pm Covalent radius 170±8 pm Spectral lines of tantalumNatural occurrence primordial Crystal structure body-centered cubic (bcc)[3] (cI2 )Lattice constant a = 330.29 pm (at 20 °C)[3] Thermal expansion 6.3 µm/(m⋅K) (at 25 °C) Thermal conductivity 57.5 W/(m⋅K) Electrical resistivity 131 nΩ⋅m (at 20 °C) Magnetic ordering paramagnetic [4] Molar magnetic susceptibility +154.0× 10−6 cm3 /mol (293 K)[5] Young's modulus 186 GPa Shear modulus 69 GPa Bulk modulus 200 GPa Speed of sound thin rod 3400 m/s (at 20 °C) Poisson ratio 0.34 Mohs hardness 6.5 Vickers hardness 870–1200 MPa Brinell hardness 440–3430 MPa CAS Number 7440-25-7 Discovery Anders Gustaf Ekeberg (1802)Recognized as a distinct element by Heinrich Rose (1844)
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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.[8] [9] Tantalum is considered a technology-critical element by the European Commission.[10]