为什么没有壳她还能活下去？

Why can she live without a shell?

youdao

大多数蜗牛背上有壳。

Most snails have shells on their backs.

youdao

然后我将木板都和我们有壳的形状。

Then I'll plank both and we have the hull shape.

youdao

The reason is because we already have a full valence shell for our hydrogen, it doesn't want any more electrons.

原因是因为我们的氢,已经有一个排满的价壳层了，它不再需要多余的电子了。

麻省理工公开课 - 化学原理课程节选

And we can generalize to figure out, based on any principle quantum number n, how many orbitals we have of the same energy, n and what we can say is that for any shell n, there are n squared degenerate orbitals.

我们可以总结出来，在，主量子数为n的情况下，同一个能量上，有多少个轨道，我们可以说，对任何壳层，有n平方个简并轨道。

麻省理工公开课 - 化学原理课程节选