Physical Chemistry Essentials - Hofmann A. 2018

The Chemical Bond
11.2 Electronegativity

The tendency of an atom to attract electrons when being part of a molecule is called electronegativity. The distribution of electrons in a heteronuclear molecules therefore can be seen as a direct result of differences in electronegativity. Accordingly, in an ionic bond, as discussed in the previous section, the difference in electronegativity between the two atoms is thus at its most extreme.

The most commonly used method to calculate electronegativity is the one proposed by Linus Pauling (Pauling 1932). In its original form, the Pauling scale of relative electronegativity values (arbitrarily) assigns a value of 4.0 to fluorine. The values of a subsequently refined scale are summarised in Table 11.1. Generally, caesium is the least electronegative element in the periodic table (0.79), while fluorine is the most electronegative (3.98).

Table 11.1

Electronegativities of the elements in their most common and stable oxidation states