That happens because of space issues that you were asked to do that, because you can always assume that all of the core orbitals are already going to be filled.

这是出于空间的考虑,要求你这么做是因为，你总是可以假定所有的,芯电子轨道都已经填满了。

麻省理工公开课 - 化学原理课程节选

So let's do a quick clicker question, and you tell me how many valence electrons does fluorine have? Remember, valence electrons are different from core, they're only the outer-most electrons in the outer-most shell.

那么让我们来做一个小选择题，请大家来告诉我,氟有多少个价电子，要记得，价电子与芯电子不同，它们是在最外壳层的最靠外面的电子。

麻省理工公开课 - 化学原理课程节选

we very rarely would see these core electrons actually being involved in any type of a reaction.

我们极少见到芯电子,会参与任何类型的反应。

麻省理工公开课 - 化学原理课程节选

So, hopefully, you remember what we mean by valence electrons versus core electrons.

希望大家还记得,价电子与芯电子的定义。

麻省理工公开课 - 化学原理课程节选

It makes a lot of sense when we look at it energetically, because if we think about a 1 s core electron, that's going to be held really, really tightly to the nucleus.

从能量的观点来看这是非常合理的，因为如果我们考虑一下，1，s，芯电子，它会被原子核束缚得非常非常紧。

麻省理工公开课 - 化学原理课程节选

Core electrons are all those electrons held in really tight with the nucleus in the inner shells, whereas the valence electrons are only those electrons that are in the outer-most shell, or at your highest value of n of the principal quantum number.

芯电子是那些,在内壳层被原子核束缚得非常紧的电子，而价电子只包括,最外层的电子，或者说主量子数，n，的值最大的那些电子。

麻省理工公开课 - 化学原理课程节选