Electronegativity (Mulliken-Jaffe) p-orbital

R.S. Mulliken proposed an electronegativity scale in which the Mulliken electronegativity, ΧM is related to the electron affinity EAv (a measure of the tendency of an atom to form a negative species) and the ionization potential IEv (a measure of the tendency of an atom to form a positive species) by the equation:

ΧM = (IEv + EAv)/2

The subscript v denotes a specific valence state - so for trigonal boron compounds, a values of electronegativity can be defined for sp2 hybrid orbitals. If the values of IE and EA are in units of MJ mol-1, then the Mulliken electronegativity ΧM can be expressed on the Pauling scale by the relationship:

ΧM = 3.48[(IEv + EAv)/2 - 0.602]

Image showing periodicity of electronegativity (Mulliken-Jaffe) p-orbital for group 5 chemical elements.
Image showing periodicity of electronegativity (Mulliken-Jaffe) p-orbital for group 5 chemical elements.

Units

Pauling scale

Notes

Values presented here are largely from reference 1. Mulliken's proposals are to be found in references 2 and 3. Tables of values are also given in references 4 and 5 as well.

You can look at visual representations of the various electronegativity scales using the following links.

Literature sources

  1. S.G. Bratsch, J. Chem. Ed., 1988, 65, 34.
  2. R.S. Mulliken, J. Chem. Phys., 1934, 2, 782.
  3. R.S. Mulliken, J. Chem. Phys., 1935, 3, 573.
  4. J.E. Huheey, E.A. Keiter, and R.L. Keiter in Inorganic Chemistry : Principles of Structure and Reactivity, 4th edition, HarperCollins, New York, USA, 1993.
  5. A.M. James and M.P. Lord in Macmillan's Chemical and Physical Data, Macmillan, London, UK, 1992.
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