thulium

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Symbol:

Tm

Atomic Number:

69

Relative Atomic Mass:

168.93421 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

2 x 10^-5% (mass fraction)

Electron Configuration:

[Xe]4f¹³6s²

Oxidation States:

III, II

Atomic Radius:

172.4pm

Covalent Radius:

156pm

Ionic Radius:

88pm (for +3 oxidation state, 6 coordinate)

105pm (for +3 oxidation state, 9 coordinate)

Melting Point:

1545°C

Density:

9.32 g cm^-3 (at 20°C)

First Ionisation Energy:

6.18 eV

Reduction Potential:

-2.31V

for Tm³⁺ + 3e^- a Tm_(s)

Electronegativity (Allred and Rochow):

1.1

Number of Natural Isotopes:

1

Mass Number of the Most Abundant Isotopes:

169 g mol^-1 a 100% abundance