potassium

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Symbol:

K

Atomic Number:

19

Relative Atomic Mass:

39.0983 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

2.4% (mass fraction)

Electron Configuration:

[Ar]4s

Oxidation States:

I

Atomic Radius:

227.2pm

Covalent Radius:

203pm

Ionic Radius:

138pm (for +1 oxidation state, 6 coordinate)

151pm (for +1 oxidation state, 8 coordinate)

Melting Point:

63.3°C

Density:

0.86 g cm^-3 (at 20°C)

First Ionisation Energy:

4.341 eV

Reduction Potential:

-2.93V

for K⁺ + e^- a K_(s)

Electronegativity (Allred and Rochow):

0.9

Number of Natural Isotopes:

3

Mass Number of the Most Abundant Isotopes:

39 g mol^-1 a 93.3% abundance

40 g mol^-1 a 0.01% abundance

41 g mol^-1 a 6.7% abundance