โ–ธโ–ธ
  • ๐Ÿ‡ฌ๐Ÿ‡ง Helium
  • ๐Ÿ‡จ๐Ÿ‡ณ ๆฐฆ
  • ๐Ÿ‡ณ๐Ÿ‡ฑ Helium
  • ๐Ÿ‡ซ๐Ÿ‡ท Hélium
  • ๐Ÿ‡ฉ๐Ÿ‡ช Helium
  • ๐Ÿ‡ฎ๐Ÿ‡ฑ ื”ืœื™ื•ื
  • ๐Ÿ‡ฎ๐Ÿ‡น Elio
  • ๐Ÿ‡ฏ๐Ÿ‡ต ใƒ˜ใƒชใ‚ฆใƒ 
  • ๐Ÿ‡ต๐Ÿ‡น Hélio
  • ๐Ÿ‡ท๐Ÿ‡บ ะ“ะตะปะธะน
  • ๐Ÿ‡ช๐Ÿ‡ธ Helio
  • ๐Ÿ‡ธ๐Ÿ‡ช Helium

Helium: properties of free atoms

Helium atoms have 2 electrons and the shell structure is  2.

The ground state electron configuration of ground state gaseous neutral helium is  1s2 and the term symbol is  1S0.

Kossel shell structure of helium
Schematic electronic configuration of helium.
Kossel shell structure of helium
The Kossel shell structure of helium.

Atomic spectrum

 

A representation of the atomic spectrum of helium.

Ionisation Energies and electron affinity

The electron affinity of helium is 0 kJ mol‑1. The ionisation energies of helium are given below.

Ionisation energies of helium
Ionisation energy number Enthalpy / kJ mol‑1
1st2372.32
2nd5250.51
Ionisation energies of helium
Ionisation energies of helium.

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 helium
1s1.6875  
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)  
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 helium. 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 1s24.6 [2]

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.