We want to discuss sigma bonds and pi bonds.

我们要讨论sigma键和π键。

youdao

So PI bonds have electron density both above and below the bond axis, but they actually have a nodal plane at this z, this bond axis here.

键在键轴之上，和之下都有电子密度，但它们在z方向有节面，这是键轴的地方。

youdao

So let's think about how we can classify single and double and triple bonds, which is what we're really used to dealing with in terms of these sigma bonds and these pi bonds.

让我们想想怎么来分类单键双键,和三键，这在我们在考虑sigma键,和π键是很有用的。

youdao

So let's have a clicker question here on how many total pi bonds do you expect to see in benzene?

让我们来做个课堂习题,你们觉得苯环里有一共多少个π键？

麻省理工公开课 - 化学原理课程节选

But, of course, what you saw in recitation, and hopefully, what you can now think very quickly by looking at this, is that this is not the only configuration of pi bonds that we could have in benzene.

当然，你们在习题课看到过，你们通过看这个可以很快的想到，这不是苯环里,唯一的π键构型。

麻省理工公开课 - 化学原理课程节选

How many pi bonds would you expe PROFESSOR: Two, great.

你们预计它有几个π键,两个，很好。

麻省理工公开课 - 化学原理课程节选