Taft's substituent constants, σ* and σ I , and Huheey's group electronegativity

For 34 groups, Taft's substituent constants σ* and σ I are found to correlate well ( r = 0.962 and 0.948) with Huheey's group electronegativity (χ H ) when Taft's steric parameter E s for a group is mixed with σ* and σ I :From these equations, it follows that for a particular chemical group G, σ*(G) ≈ 8σ I (G). Since the σ* scale is essentially based on the σ I scale, the small inherent steric component in σ I is amplified in the case of the σ* by a factor of ca 8. An analysis shows that χ H represents the electronegativity of a group when the group is considered to be a mere collection of non‐bonded, charged and suitably hybridized atoms. Thus σ* and σ I are found to represent the electronegativity of a group in the spirit of the χ H . It is concluded that a chemical group can be viewed as a collection of non‐interacting atoms. Although there is evidence that a molecule can sometimes be treated similarly, for a group such a situation is novel.