promethium

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Symbol:

Pm

Atomic Number:

61

Relative Atomic Mass:

146.9151 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

10^-19% (mass fraction)

Electron Configuration:

[Xe]4f⁵6s²

Oxidation States:

III

Atomic Radius:

163pm

Ionic Radius:

97pm (for +3 oxidation state, 6 coordinate)

114pm (for +3 oxidation state, 9 coordinate)

Melting Point:

1080°C

Density:

7.22 g cm^-3 (at 20°C)

First Ionisation Energy:

5.55 eV

Reduction Potential:

-2.29V

for Pm³⁺ + 3e^- a Pm_(s)

Electronegativity (Allred and Rochow):

1.1