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

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。

麻省理工公开课 - 化学原理课程节选

Another way to represent a point in a plane is I've got a radius and I've got an angle from the x-axis, right, and that's a standard thing you might do.

平面上面的点的方法,也就是极坐标,上面那种方法其实是，如果你们喜欢我这么说的话,笛卡尔坐标表示法。

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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。

麻省理工公开课 - 化学原理课程节选

The reason that it's sigma is if you look at the bonding axis here, is that there is no nodal plane along the bonding axis.

它是sigma键的原因是,因为如果你看键轴，上面是没有节面的。

麻省理工公开课 - 化学原理课程节选

But in sigma orbitals, you have no nodal planes along the bond axis, so if we had a nodal plane here, we'd see an area where the wave function was equal to zero.

但在sigma轨道里，沿着轴向是没有节点平面的，如果我们有个节点，我们就会看到某个地方波函数等于0。

麻省理工公开课 - 化学原理课程节选

So again, we can name these molecular orbitals and these we're going to call also to point out there is now a bond axis along this nodal plane, which is something we didn't see before when we were combining the s orbitals.

同样的，我们可以,命名这些分子轨道,这些轨道叫做-同样要指出的是,现在沿着键轴是一个节点面，这是我们讨论s轨道的时候,从没有看到过的。

麻省理工公开课 - 化学原理课程节选