thorium

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Symbol:

Th

Atomic Number:

90

Relative Atomic Mass:

232.0381 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

10^-3% (mass fraction)

Electron Configuration:

[Rn]6d²7s²

Oxidation States:

IV

Atomic Radius:

179.8pm

Covalent Radius:

165pm

Ionic Radius:

94pm (for +4 oxidation state, 6 coordinate)

105pm (for +4 oxidation state, 8 coordinate)

Melting Point:

1750°C

Density:

11.72 g cm^-3 (at 20°C)

First Ionisation Energy:

6.95 eV

Reduction Potential:

-1.90V

for Th⁴⁺ + 4e^- a Th_(s)

Electronegativity (Allred and Rochow):

1.1

Number of Natural Isotopes:

2

Mass Number of the Most Abundant Isotopes:

232 g mol^-1 a 100% abundance