tantalum

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Symbol:

Ta

Atomic Number:

73

Relative Atomic Mass:

180.9479 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

8 x 10^-4% (mass fraction)

Electron Configuration:

[Xe]4f¹⁴5d³6s²

Oxidation States:

V

Atomic Radius:

143pm

Covalent Radius:

134pm

Ionic Radius:

64pm (for +5 oxidation state, 6 coordinate)

74pm (for +5 oxidation state, 8 coordinate)

Melting Point:

2996°C

Density:

16.68 g cm^-3 (at 20°C)

First Ionisation Energy:

7.89 eV

Reduction Potential:

-0.750V

for TaO_5/2 + 5H⁺ + 5e^- a Ta_(s) + 5/2H₂O

Electronegativity (Allred and Rochow):

1.3

Number of Natural Isotopes:

2

Mass Number of the Most Abundant Isotopes:

180 g mol^-1 a 0.01% abundance

181 g mol^-1 a ~100% abundance