L.C. Allen suggests that electronegativity is the average one-electron energy of the valence shell electrons in the ground state free atoms. This means that values of the Allen electronegativity can be calculated from spectroscopic data. The values obtained correlate well with Pauling electronegativity and with Allred-Rochow electronegativity. The Allen electronegativity is given the symbol Χspec.
The Allen electronegativity is given the symbol Χspec. For the s- and p-block elements, then:
Χspec = (mεs + nεp)/(m + n)
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