Other treatments25 have led to scales that are based on different principles, for example, the average of the ionization potential and the electron affinity,26 the average one-electron energy of valence-shell electrons in ground-state free atoms,27 or the ‘‘compactness’’ of an atom’s electron cloud.24 In some of these treatments electronegativities can be calculated for different valence states, for different hybridizations (e.g., sp carbon atoms are more electronegative than sp2, which are still more electronegative than sp3),28and even differently for primary, secondary, and tertiary carbon atoms. Also, electronegativities can be calculated for groups rather than atoms (Table 1.2).29