which straightforwardly describes that moving to the neighboring carbon atom makes a π rad ≡ 180 • change in phase. It does directly correspond to the atom-wise charge alternation related to the law of alternating polarity. Chemically, the external negative point charge pushes out the electron density from the closest carbon atom, thus polarising the nearest C-C bond. Such polarization then propagates farther down the chain via the mesomeric effect, alternatingly.