And the last thing we do for any of our structures to check them and figure out are these valid or not valid, are these good Lewis structures is to check the formal charge.

而为了检验任何一个结构是否有效,看它们是不是好的路易斯结构,我们要做的最后一件事就是检查形式电荷。

麻省理工公开课 - 化学原理课程节选