原子核对最外层电子的作用受到屏蔽。

The outermost electron is shielded from the nucleus.

youdao

这些元素，不像过渡金属那样显示出可变的化合价，他们只有最外层电子参加反应。

These elements, unlike the transition elements, do not exhibit variable oxidation states, and their valence electrons are only present in their outer shell.

youdao

所有的稀有气体元素的最外层电子数都是该层最大的可能数目：氦的最外层电子有两个，其它的稀有气体最外层电子数是八。这使稀有气体非常稳定。

All noble gases have the maximum number of electrons possible in their outer shell (two for helium, eight for all others), making them highly stable.

youdao

There is a huge difference between the energies in the outermost shell and the inner shells, which tells you that it's unlikely that any electrons except those in the outermost shell are going to be active.

最外层和最里层所具有的能量,有很大差异，而这告诉我们有一点是不太可能的,那就是除了最外层的电子,别的电子都是应该是活泼的。

麻省理工公开课 - 固态化学导论课程节选

And remember, we're only talking about valence electrons, so the outer-most shells.

要记得，我们讨论的只是价电子，也就是最外层的电子。

麻省理工公开课 - 化学原理课程节选

And, one other thing that I failed to point out, if you take a look at the energies associated with the outermost electrons, in this case, lithium, you see it's 0.5 megajoules per mole, and then what's the 6.26?

还有另外一点我忘记提到的是，如果你观察离最外层,的电子的能量，在这种情况，对于锂，你可以得到，它是每摩尔0。5兆焦，那么6。26是什么呢？

麻省理工公开课 - 固态化学导论课程节选