And in contrast, in the lower left hand part of the periodic table, these 2 quantities are low, so also what we're going to see is low electronegativity.

相反地，在周期表的左下部分，这两个量的值都很小，因此我们会看到这里的电负性也很低。

麻省理工公开课 - 化学原理课程节选

And we know as we go across a row in the periodic table, what's happening is that z effective or the effective pull on the nucleus is increasing.

而我们知道沿着周期表的某一行向右看，有效核电量,或者说原子核的有效引力是在逐渐增大的。

麻省理工公开课 - 化学原理课程节选

So it looks like not too many more than half of you got this correct, so make sure you can look at your periodic table and figure out how to think about ionization energy in terms of z effective, not just in terms of memorizing what that trend is.

看起来只有一半多一点的人,做对了，所以请大家务必做到能够通过观察周期表,并在考虑电离能时,从有效核电量的观点出发，而不是仅仅依靠记住这个规律。

麻省理工公开课 - 化学原理课程节选

So, for example, we have this average level, and then it can go high where we have the peak, or it can go very low. We can also discuss sound waves, so again it's just the periodic variation of some property -- in this case we're talking about density, so we have high density areas and low density areas.

例如这是平均位置，在峰的位置水位高，在谷水位低，我们也可以,讨论声波它也是某种,量的周期变化，在这里我们,讨论的是密度,我们有高密度区和低密度区。

麻省理工公开课 - 化学原理课程节选