What I just spent many lectures discussing is the fact that we can not know how far away an electron is from the nucleus, so we can't actually know the radius of a certain atom.

我花了这么多课时所讨论的正是我们,不可能知道电子离原子核有多远这一事实，因此我们不可能知道某个原子的半径。

麻省理工公开课 - 化学原理课程节选

So, actually we don't have to worry about this fact any time we're dealing with neutrals.

所以事实上当我们在处理,中性原子的时候我们不必担心。

麻省理工公开课 - 化学原理课程节选

I would say with the aid of an energy level diagram explain the fact that helium is found as atomic gas and not molecular. How about this one?

我要说的是，在能级图的帮助下,可以解释氦气是单原子气体,而不是分子气体这一事实,那么这个呢？

麻省理工公开课 - 固态化学导论课程节选