Helium: orbital properties

Valence shell orbital radii

The following are calculated values of valence shell orbital radii, Rmax

Table: valence shell orbital radii for helium.
Orbital Radius [/pm] Radius [/AU]
s orbital 30.1 0.569176
p orbital no data no data
d orbital no data no data
f orbital no data no data

Valence shell radii (valence s-orbital)


The Rmax values for neutral gaseous element valence orbitals are abstracted from reference 1.

  1. J.B. Mann, Atomic Structure Calculations II. Hartree-Fock wave functions and radial expectation values: hydrogen to lawrencium, LA-3691, Los Alamos Scientific Laboratory, USA, 1968.

Effective Nuclear Charges

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

Table: effective nuclear charges for helium
1s 1.69  
2s no data 2p no data  
3s no data 3p no data 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  

Effective nuclear charge (Clementi): 1s orbital


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

This table contains electron binding energies for helium.
Label Orbital eV [literature reference]
K 1s 24.6 [2]

Electron binding energy for K shell


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.

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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helium atomic number