And what we've been talking about with all of these properties are, of course, how can we figure out what that is for a certain atom by looking at the periodic table, so we want to think about the periodic trend for atomic radius.

对于我们讲过的这些性质，我们所讨论的一直都是,当然是，我们如何能够判断某一个原子的这些性质,通过观察周期表，因此我们需要思考一下原子半径的周期性规律。

麻省理工公开课 - 化学原理课程节选