These are highly reactive because they have seven valence electrons.

它们具有很高的反应性，因为它们有七个价电子。

They tend to have the same number of valence electrons.

它们往往具有相同数量的价电子。

How many Valence electrons does sodium have?

钠有多少个价电子？

So large, that the valence electrons aren't held very strongly by the nucleus.

如此之大，以至于价电子不会被原子核牢固地保持。

They would love nothing more than to get one more valence electron.

他们只想再得到一个价电子。

Once again, it has one valence electron, one electron in its outermost shell.

同样，它有一个价电子，一个位于最外层的电子。

All of the elements in group two are going to have two Valence electrons.

第二组中的所有元素都有两个价电子。

We could depict them as one, two, three, four Valence electrons.

我们可以将它们描述为一个、两个、三个、四个价电子。

And valence electrons are electrons in the outermost shell they tend to coincide, although there's a slightly different variation.

价电子是最外层的电子，它们往往重合，尽管变化略有不同。

Because they have eight valence electrons.

因为它们有八个价电子。