thallium

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Symbol:

Tl

Atomic Number:

81

Relative Atomic Mass:

204.3833 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

3 x 10^-5% (mass fraction)

Electron Configuration:

[Xe]4f¹⁴5d¹⁰6s²6p

Oxidation States:

III, I

Atomic Radius:

170pm

Covalent Radius:

155pm

Ionic Radius:

89pm (for +3 oxidation state)

150pm (for +1 oxidation state)

Melting Point:

303.5°C

Density:

11.85 g cm^-3 (at 20°C)

First Ionisation Energy:

6.108 eV

Reduction Potential:

-0.336V

for Tl⁺ + e^- a Tl_(s)

Electronegativity (Allred and Rochow):

1.4

Number of Natural Isotopes:

2

Mass Number of the Most Abundant Isotopes:

203 g mol^-1 a 29.5% abundance

205 g mol^-1 a 70.5% abundance