Iron: properties of free atoms

Iron atoms have 26 electrons and the shell structure is  2.8.14.2.

The ground state electron configuration of ground state gaseous neutral iron is  [Ar].3d6.4s2 and the term symbol is  5D4.

Atomic spectrum

 

A representation of the atomic spectrum of iron.

Electronic configuration of neutral atomic iron

Electronic configuration of iron

The electronic configuration of iron.

Kossel shell structure of iron

The Kossel shell structure of iron.

Ionisation Energies and electron affinity

The electron affinity of iron is 15.7 kJ mol‑1. The ionisation energies of iron are given below.

Ionisation energies of iron
Ionisation energy number Enthalpy / kJ mol‑1
1st762.5
2nd1561.9
3rd2957
4th5290
5th7240
6th9560
7th12060
8th14580
9th22540
10th25290
11th28000
12th31920
13th34830
14th37840
15th44100
16th47206
17th122200
18th131000
19th140500
20th152600
21st163000

Effective Nuclear Charges

The following are "Clementi-Raimondi" effective nuclear charges, Zeff. Follow the hyperlinks for more details and for graphs in various formats.

Effective nuclear charges for iron
1s25.38  
2s18.60 2p22.09  
3s13.68 3p12.78 3d11.18  
4s5.43 4p(no data) 4d(no data) 4f(no data)
5s(no data) 5p(no data) 5d(no data)  
6s(no data) 6p(no data)  
7s   

References

These effective nuclear charges, Zeff, are adapted from the following references:

  1. E. Clementi and D.L.Raimondi, J. Chem. Phys. 1963, 38, 2686.
  2. E. Clementi, D.L.Raimondi, and W.P. Reinhardt, J. Chem. Phys. 1967, 47, 1300.

Electron binding energies

Electron binding energies for iron. All values of electron binding energies are given in eV. The binding energies are quoted relative to the vacuum level for rare gases and H2, N2, O2, F2, and Cl2 molecules; relative to the Fermi level for metals; and relative to the top of the valence band for semiconductors.
Label Orbital eV [literature reference]
K 1s7112 [1]
L I2s844.6 [3]
L II2p1/2719.9 [3]
L III2p3/2706.8 [3]
M I3s91.3 [3]
M II3p1/252.7 [3]
M III3p3/252.7 [3]

Notes

I am grateful to Gwyn Williams (Jefferson Laboratory, Virginia, USA) who provided the electron binding energy data. The data are adapted from references 1-3. They are tabulated elsewhere on the WWW (reference 4) and in paper form (reference 5).

References

  1. J. A. Bearden and A. F. Burr, "Reevaluation of X-Ray Atomic Energy Levels," Rev. Mod. Phys., 1967, 39, 125.
  2. M. Cardona and L. Ley, Eds., Photoemission in Solids I: General Principles (Springer-Verlag, Berlin) with additional corrections, 1978.
  3. Gwyn Williams WWW table of values
  4. D.R. Lide, (Ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 81st edition, 2000.
  5. J. C. Fuggle and N. Mårtensson, "Core-Level Binding Energies in Metals," J. Electron Spectrosc. Relat. Phenom., 1980, 21, 275.

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