If we have a higher z effective, it's pulled in tighter, we have to put in more energy in order to eject an electron, so it turns out that that's why case 2 is actually the lowest energy that we need to put in.

而如果有效核电量更高，原子核的束缚也就更紧，我们不得不输入更多的能量来打出一个电子，这就是第二种情况,所需要输入的,能量更少的原因。

麻省理工公开课 - 化学原理课程节选

You'll have... you know, shops will be tinier and they will just be right next to each other.

你会有……那儿的商店会更小，它们真的就是一间紧挨着下一间的。

哈莱姆很独特 - SpeakingMax英语口语达人

The reason it's aluminum is because aluminum has a lower z effective, so it's not being pulled in as tightly by the nucleus, and if it's not being pulled in as tightly, you're going to have to put in less energy in order to ionize it, so that's why it's actually going to have the smaller ionization energy.

原因是,铝的有效核电量更少，所以没有被原子核束缚得更紧，而如果没有被束缚得更紧，你为了电离它所需要注入的能量也就更少，这就是,它的电离能会更低的原因。

麻省理工公开课 - 化学原理课程节选