erbium

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Symbol:

Er

Atomic Number:

68

Relative Atomic Mass:

167.26 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

2 x 10^-4% (mass fraction)

Electron Configuration:

[Xe]4f¹²6s²

Oxidation States:

III

Atomic Radius:

173.4pm

Covalent Radius:

157pm

Ionic Radius:

89pm (for +3 oxidation state, 6 coordinate)

106pm (for +3 oxidation state, 9 coordinate)

Melting Point:

1522°C

Density:

9.05 g cm^-3 (at 20°C)

First Ionisation Energy:

6.10 eV

Reduction Potential:

-2.31V

for Er³⁺ +3e^- a Er_(s)

Electronegativity (Allred and Rochow):

1.1

Number of Natural Isotopes:

6

Mass Number of the Most Abundant Isotopes:

166 g mol^-1 a 33.6% abundance

167 g mol^-1 a 22.9% abundance

168 g mol^-1 a 26.8% abundance