Pi orbitals are a molecular orbital that have a nodal plane through the bond axis.

轨道是沿着键轴,有节面的分子轨道。

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Sigma that is one PI orbital. There is one sigma, one PI and there is a second PI, and that is how we are getting the triple bond.

那是一个pi轨道，有一个，一个pi，还有第二个pi轨道，这就是我们如何得到三线态的。

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And this will be called pi of 2py molecular orbital.

我们会称它为2py分子轨道上的π键。

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So even though we see a nodal plane down the center, I just want to really point out that it's only when we have a nodal plane in the internuclear or the bond axis that we're calling that a pi orbital.

虽然在中间有个节面，我想要指出的是,只有节面在核间轴,或者键轴上时,我们才叫它π轨道。

麻省理工公开课 - 化学原理课程节选

The reason that I wanted to point out this nodal plane here is because this is why it is called a pi orbital.

我指出这个节面的原因是因为,它就是为什么这个叫做π轨道的原因。

麻省理工公开课 - 化学原理课程节选

sigma That is one pi orbital. There is one sigma, one pi and there is a second pi, and that is how we are getting the triple bond.

那是一个pi轨道，有一个，一个pi，还有第二个pi轨道，这就是我们如何得到三线态的。

麻省理工公开课 - 固态化学导论课程节选