The electronic factor, or electronic effect, is the influence on a reaction rate that arises from how charge or partial charge is distributed and stabilised within a molecule. It matters because stabilising the charge that develops in an intermediate or transition state lowers the energy barrier and speeds the reaction. In nucleophilic substitution, for example, stabilising the positive charge of the carbenium ion favours the SN1 reaction. It is distinguished from the steric factor, which concerns the size of groups rather than charge.

电子因素(电子效应)是指由分子内电荷或部分电荷的分布与稳定程度引起的、对反应速率的影响。它之所以重要,是因为稳定中间体或过渡态中产生的电荷会降低能垒、加快反应。例如在亲核取代中,稳定碳正离子的正电荷有利于 SN1 反应。它与空间因素相区别,后者关乎基团的大小而非电荷。