Chemical shifts in core electron binding energies can be predicted by the equation ..delta..E/sub B/ = aF + bR, where the parameters a and b are characteristic of the class of molecule and atom to which the binding energies pertain, and the parameters F and R are characteristic of substituent groups. The F and R parameters are analogous to the Swain and Lupton ''F'' and ''R'' parameters; i.e., they measure the sigma and ..pi.. electronegativities, respectively, of substituents. However, the F and R values are appropriate only for processes in which a localized positive charge develops on an atom, whereas the ''F'' and ''R'' values are appropriate for ordinary chemical reactions (including both electrophilic and nucleophilic substitutions). Thus lone-pair ionization potentials and proton affinities can be correlated with F and R values more satisfactorily than with ''F'' and ''R'' values.