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

So what we see is that those six pi electrons are actually going to be de-localized around all six of those atoms.

我们看到,六个π电子会,巡游在所有六个原子周围。

麻省理工公开课 - 化学原理课程节选

And we can simplify this expression as saying negative e squared over 4 pi, epsilon nought r squared. Epsilon nought is a constant, it's something you might see in physics as well.

也会遇到它,在这里，你可以就把它,理解为一个转换系数,我们需要做的。

麻省理工公开课 - 化学原理课程节选

So if I try to rotate my 2 atoms, you see that I have to break that pi bond, because they need to be lined up so that the electron density can overlap.

如果我要试着转动两个原子，你会看到我必须要打破一个π键，因为他们需要连接起来,让那些电子能够重叠。

麻省理工公开课 - 化学原理课程节选

So it's very important to be keeping in mind that any time you see a double bond, you have a pi bond there, so you're not going to see any rotation around the bond axis.

所以你们要记住,任何时候你们看到一个双键，这里面有π键，你们不会看到关于键轴的任何转动。

麻省理工公开课 - 化学原理课程节选

So, we're going to see two pi bonds.

我们可以看到两个π键。

麻省理工公开课 - 化学原理课程节选

When we look at this angular part, we see that it's always the square root of 1 over 4 pi, it doesn't matter what the angle is, it's not dependent on the angle.

当我们看这角向部分，可以看到它总是等于１除以４pai开根号，这和是什么角度没有关系，它和角度无关。

麻省理工公开课 - 化学原理课程节选

Another thing I want to point out about every sigma orbital that you see, and it will make more sense when we contrast it with pi orbitals later.

另外一个我要指出的事情就是,关于每个sigma轨道你能看到,当我们把它和π轨道对比的时候会看的更清楚。

麻省理工公开课 - 化学原理课程节选

You can see that we have two unpaired electrons in this molecule here one in the pi 2 p x star, and one in the pi 2 p y star orbital.

你们可以看到我们这个,分子力有两个未配对电子,一个在π2px星，一个在π2py星轨道。

麻省理工公开课 - 化学原理课程节选