73TaTantalum

Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as tantalium, 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. Tantalum is considered a technology-critical element by the European Commission.

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Atomic properties

Standard atomic weight180.947 ±2·10-5
Atomic mass180.947 u

Atomic radii

Radius (empirical)146 pm
Radius (calculated)200 pm
Covalent radius170 ±8 pm

Atomic shell

Electron configurationXe 4f14 5d3 6s2
Ionization energy(1st) 7.549571 eV
(2nd) 16.2 eV
(3rd) 32.1 eV
(4th) 35 eV
(5th) 48.272 eV
Shell model
Electrons
k-shell:2
l-shell:8
m-shell:18
n-shell:32
o-shell:11
p-shell:2

Physical properties

Phasesolid
Density16.65 g·cm−3 (293.1 K)
Molar volume1.085·10-5 m3·mol−1
Speed of sound3,400 m·s−1 (293.1 K)

Temperatures

Melting point3,290 K
Boiling point5,731 K
Liquid range2,441 K
Transition temperature4.4 K

Enthalpies

Melting enthalpy36 kJ·mol-1
Enthalpy of vaporization735 kJ·mol-1
Binding energy782 kJ·mol-1

Heat and conductivity

Specific heat capacity140 J·kg−1·K−1
Thermal conductivity57 W·m-1·K-1
Expansion coefficient6.3·10-6 K-1

Hardnesses

Mohs hardness6.5
Brinell hardness800 NM·m-2
Vickers hardness873 NM·m-2

Elastic properties

Young’s modulus186 GPa
Shear modulus69 GPa
Bulk modulus200 GPa
Poisson’s ratio0.34

Electrical properties

Electrical conductivity7.61·106 S·m-1
Resistance1.35·10-7 Ωm

Magnetism

Magnetismparamagnetic
Magnetic susceptibility1.54·10-4 cm3·mol−1 (293 K)

Optical properties

Reflectivity78 %

Chemical properties

Basicityslightly acidic
Oxidation state5
Standard potential-0.81 V (½Ta2O5 + 5H+ + 5e- → Ta + 2½H2O)

Electronegativity

Pauling scale1.5
Allred-Rochow scale1.33
Nagle scale1.26
Pearson absolute negativity4.11 eV

Other properties

Natural occurrenceprimordial
Crystal structureBody-centered cubic
Goldschmidt Classificationlithophile
Superconductorwith transition tempperature (solid body, normal pressure)
Price/kg305 ±7 USD

Natural abundances

satellite_alt
Universe
0.08 ppb ≈ 8.04·108 M☉
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destruction
Meteorite
20 ppb ≈ 20 mg
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Earth’s crust
1,700 ppb ≈ 47,000 Mt
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Oceans
0.002 ppb ≈ 2.74 kt
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