Now let's think about this first pi bond, which will be above and below the bonding axis.

让我们先来看这个π键，它在键轴的上面和下面。

麻省理工公开课 - 化学原理课程节选

So there's electron density above the bond and below the bond.

所以在键轴上面和下面都有电荷密度。

麻省理工公开课 - 化学原理课程节选

Here for example we have the pitch C and either note above or below it is dissonant.

如果说这里用C音，那么不管是和它上面还是下面的音符搭配都不和谐。

耶鲁公开课 - 聆听音乐课程节选

All right, so what we see here is we have our sigma bond that's along the internuclear axis here, but we also have a pi bond, because each of these atoms now has electrons in it's in a p orbital, so we're going to overlap of electron density above and below the bond.

这里我们看到sigma键,是沿着核间轴的，但我们还有一个π键，因为每个原子的p轨道上,都有电子，所以电子密度在键的上面,和下面都有电子密度交叠。

麻省理工公开课 - 化学原理课程节选