Silicon: properties of free atoms

Silicon atoms have 14 electrons and the shell structure is  2.8.4.

The ground state electron configuration of ground state gaseous neutral silicon is  [Ne].3s2.3p2 and the term symbol is  3P0.

Atomic spectrum


A representation of the atomic spectrum of silicon.

Electronic configuration of neutral atomic silicon

Electronic configuration of silicon

The electronic configuration of silicon.

Kossel shell structure of silicon

The Kossel shell structure of silicon.

Ionisation Energies and electron affinity

The electron affinity of silicon is 133.6 kJ mol‑1. The ionisation energies of silicon are given below.

Ionisation energies of silicon
Ionisation energy number Enthalpy / kJ mol‑1

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 silicon
2s9.02 2p9.95  
3s4.90 3p4.29 3d(no data)  
4s(no data) 4p(no data) 4d(no data) 4f(no data)
5s(no data) 5p(no data) 5d(no data)  
6s(no data) 6p(no data)  


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 silicon. 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 1s1839 [1]
L I2s149.7 [2, values derived from reference 1]
L II2p1/299.8 [2]
L III2p3/299.2 [2]


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).


  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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