Electronegative difference, Pauling

Calculated by the SHOMAKER-STEVENSON equation corrected for electronegativity differences (PAULING). 

Pauling s electronegativity difference, where represents the electronegativity of atom X. 

See Pauling, note 14, pp. 97ff. Coulson, note 21, p. 141, states Now there must be some relation between the percentage ionic character and the electronegativity difference xB — xA. It is of the very essence of the idea of an electronegativity scale that this should be so. ... 

One classical example that apphes the electroneutrality principle is the electronic structure of carbon monoxide, a diatomic molecule with a very small dipole moment of 0.110 debye. The only electronic structure that satisfies the octet rule for CO is C=0 , a structure that corresponds to C and O, if the shared electron pairs are equally devided by the two atoms. Pauling showed that the electronegativity difference of 1.0 would correspond to about 22% partial ionic character for each bond, and to charges of and 0° +. A second possible electronic structure, C=O , does not complete the octet for carbon. The partial ionic character of the bonds corresponds to C0.44+ If these two structures contribute... 

The electronegativity difference between boron and nitrogen (2.0 and 3.0, respectively, on the Pauling scale) results in a polar B-N bond. The regio-selectivity of the reactions of borazines with electrophiles and nucleophiles can be understood in this context. Thus the reaction of borazine with three equivalents of HCl produces (C1HBNH2)3 in which the proton seeks out the nitrogen centres and the chloride ions become attached to boron. ... 

In Eq. 2.49a, the arithmetic mean of Daa and Dab is taken, as is usual, but some authors use the geometric mean as in Eq. 2.49b to avoid negative ZIab values in a few cases involving very weak bonds. Either way, the Pauling electronegativity difference between A and B is defined by... 

Gordy s electronegativity differences are very nearly proportional to Pauling s (0.62 Gordy unit per Pauling unit) the two scales become almost identical if 0.80 is added to each of Gordy s values ... 

At the present stage of theoretical development it is hardly possible to go far enough, in terms of either band theory or the Pauling valence bond approximation, with a quantitative treatment of crystals involving free electrons and a relatively large electronegativity difference between the components. Nevertheless, the matter merits more attention. 

Table 7.1. Degree of covalence of different ceramics according to the scale of electronegativity of Pauling (1960).

On the basis of electronegativity concept, Pauling formulated the following rule the larger is the difference between the electronegativities of elements, the higher is the energy of the bond between atoms. 

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