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gray blue
General properties
Name, symbol, number tantalum, Ta, 73
Group, period, block 56, d
Standard atomic weight {{{atomic mass}}} g/mol
Electron configuration [Xe] 4f14 5d3 6s2
Electrons per shell 2, 8, 18, 32, 11, 2 (Image)
Physical properties
Phase solid
Density (near r.t.) 16.69 g/cm3
Liquid density at m.p. 15 g/cm3
Melting point 3290 K, 3017 °C, 5463 °F
Boiling point 5731 K, 5458 °C, 9856 °F
Heat of fusion 36.57 kJ/mol
Heat of vaporization 753 kJ/mol
Specific heat capacity (25 °C) 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
Atomic properties
Oxidation states 5, 4, 3, 2, 1, −1, −3
((a mildly acidic oxide))
Electronegativity 1.5 (Pauling scale)
Ionization energies 1st: {{{1st ionization energy}}} kJ/mol
2nd: {{{2nd ionization energy}}} kJ/mol
Atomic radius 146 pm
Covalent radius 170±8 pm
Crystal structure body-centered cubic
Crystal structure note α-Ta
Magnetic ordering paramagnetic
Electrical resistivity (20 °C) 131Ω·m
Thermal conductivity (300 K) 57.5 W/(m·K)
Thermal expansion (25 °C) 6.3 µm/(m·K)
Speed of sound (thin rod) (20 °C) 3400 m/s
Young's modulus 186 GPa
Shear modulus 69 GPa
Bulk modulus 200 GPa
Poisson ratio 0.34
Mohs hardness 6.5
Vickers hardness 870–1200 MPa
Brinell hardness 440–3430 MPa
CAS registry number 7440-25-7
Most stable isotopes
Main article: Isotopes of tantalum
iso NA half-life DM DE (MeV) DP
177Ta syn 56.56 h ε 177Hf
178Ta syn 2.36 h ε 178Hf
179Ta syn 1.82 y ε 179Hf
180Ta syn 8.125 h ε 180Hf
β 180W
180mTa 0.012% stable
181Ta 99.988% stable
182Ta syn 114.43 d β 182W
183Ta syn 5.1 d β 183W
Tantalum in a glass tube

Tantalum is a chemical element. Tantalum was named tantalium. It has the chemical symbol Ta. It has the atomic number 73. It is a rare metal. It is hard and blue-gray. In chemistry it is placed in a group of metal elements named the transition metals.

Tantalum does not easily corrode. It is found in the mineral tantalite.

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