caesium

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Symbol:

Cs

Atomic Number:

55

Relative Atomic Mass:

132.90545 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

6 x 10^-4% (mass fraction)

Electron Configuration:

[Xe]6s

Oxidation States:

I

Atomic Radius:

265.5pm

Covalent Radius:

253pm

Ionic Radius:

167pm (for +1 oxidation state, 6 coordinate)

174pm (for +1 oxidation state, 8 coordinate)

Melting Point:

28.4°C

Density:

1.90 g cm^-3 (at 20°C)

First Ionisation Energy:

3.894 eV

Reduction Potential:

-2.92V

for Cs⁺ + e^- a Cs_(s)

Electronegativity (Allred and Rochow):

0.9

Number of Natural Isotopes:

1

Mass Number of the Most Abundant Isotopes:

133 g mol^-1 a 100% abundance