It is of opposite charge and it exerts an influence, only that is minus to plus so that is going to give me a minus term here.

它具有相反的电性，所以它也会有影响，只有这个负值相对正值来说会起到减少的作用,所以这里将会引入一个负值的量。

麻省理工公开课 - 固态化学导论课程节选