iron

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Symbol:

Fe

Atomic Number:

26

Relative Atomic Mass:

55.845 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

4.7% (mass fraction)

Electron Configuration:

[Ar]3d⁶4s²

Oxidation States:

VI, III, II, 0, -II

Atomic Radius:

124.1pm

Covalent Radius:

116pm

Ionic Radius:

65pm (for +3 oxidation state)

78pm (for +2 oxidation state)

(Values are for high-spin complexes)

Melting Point:

1535°C

Density:

7.87 g cm^-3 (at 20°C)

First Ionisation Energy:

7.870 eV

Reduction Potential:

-0.447V

for Fe²⁺ + 2e^- a Fe_(s)

Electronegativity (Allred and Rochow):

1.6

Number of Natural Isotopes:

4

Mass Number of the Most Abundant Isotopes:

54 g mol^-1 a 5.8% abundance

56 g mol^-1 a 91.8% abundance

57 g mol^-1 a 2.1% abundance