# Relation between ionic resonance energy and polarity

The ionic resonance of the bonds are given as follows:

$$\begin{array}{cr} \ce{A-B} & 24.3 \\ \ce{A-C} & 50.6 \\ \ce{A-D} & 102.3 \\ \ce{A-E} & 105.9 \end{array}$$

Which of the bonds is the most polar?

a) $$\ce{A-B}$$
b) $$\ce{A-C}$$
c) $$\ce{A-D}$$
d) $$\ce{A-E}$$

I thought that more the resonance energy, more is the electron delocalisation and less polar is the bond, but this is not the case with the answer given. I was getting a), but the answer is d).

• Ionic resonance means including contributions to the structure from species such as $A^+B^-$ or $A^-B^+$ in a molecule of type AB. In this case (d) would seem to be correct. – porphyrin May 2 '19 at 18:03