To develop a model that best represents these resonance, inductive and other effects mentioned above, we first investigated how far the resonance and inductive effects could travel. As can be seen in Figures and, electron-withdrawing and donating groups (EWG, EDG) in aliphatic molecules modulate pKa even if it is as far as seven bonds away. Thus, our method should include the effect of atoms at least up to 7 bonds away from the ionization center but could ignore atoms further away without an expected loss of accuracy.