Allen electronegativity scale

L. C. Allen, Electronegativity is the average one-electron energy of the valence-shell electrons in ground-state free atoms. J. Am. Chem. Soc., Ill, 9003-9014 (1989) L. C. Allen, Electronegativity scales. Acc. Chem. Res., 23, 175 (1990). 

The electronegativity scale proposed by Allen is defined in terms of the average energy of the electrons in the valence s and p orbitals of an atom ... 

In spite of the widespread use of electronegativity as a unifying concept in organic chemistry, the electronegativity of an element is almost never included in the periodic table. Redressing this deficiency, Allen strikingly showed his electronegativity scale as the third dimension of the periodic table, and his vivid picture is adapted here as Fig. 1.55. 

Analyzing the electronegativity scales, Leland Allen has written much on criteria which good models has to fulfill see (Murphy et al., 2000) and the references therein. 

The ionization energies of ground-state atoms are considerably larger than their electron afiinities, hence EN is defined mostly by Iq. Therefore Allen et al. [406-408] introduced the atomic electronegativity scale based upon the spectroscopic (averaged) ionization energies of the valence electrons in a ground-state free atom ... 

Allen, L. C.J.Arn. Chem. Stic. 1989. 111,9003-9014, Acc. Client. Res. IWO,23, 173-176 A Am. Chem. Stic. 1992.114,1510-1511 Can. J. Chem. 1992,70.631-635. Note that Allen s spectroscopic electronegativity, like Mulliken s. will normally be expressed in terms of electron volts, but can he converted to the Pauling scale if desired. 

More recently, in 1989, Allen developed his spectroscopic scale, xs, where he equated the electronegativity of an atom to its configuration energy (CE)... 

Other scales have been proposed, namely by Allred and Rochow, in 1958 (ref. 75), and by Allen, in 1989 (ref. 76). In the first case, the electronegativity, xarj is an atomic property taken proportional to the force exerted by the effective nuclear charge at the periphery of the atom ... 

Figure 8.8 Plots of the Mulliken, scaled Pauling, and scaled Allen Rochow electronegativities of the elements versus the atomic number to illustrate the consistency and differences between the measures of electronegativity [41, 42].

TABLE 5.12 Electronegativities of selected elements using the revised Pauling scale, the Mulliken-Jaffe scale, and Allen s spectroscopic configuration energies. The iatter scales have been converted to the revised Pauling scale. The Mulliken-Jaffe values are listed for the sp valence hybridization, uniess otherwise indicated. 

---