我们回到那个三角形：从上往下，你看能到三个平等的节点。

Let's go back to that triangle; seen from above there's three equal nodes.

youdao

一个节点，2减去1等于1,因为l等于1,我们有一个角向节点，那剩下径向节点有多少个呢？

Yup, so one total node, 2 minus 1 is 1, and that means since l is equal to 1, we have one angular nodes, and that leaves us with how many radial nodes?

youdao

当我们谈到角向节点时，一个轨道的，角向节点数等于l。

And when we talk about angular nodes, the number of angular nodes we have in an orbital is going to be equal to l.

youdao

So, let me get a little bit more specific about what we mean by nodal plane and where the idea of nodal plane comes from, and nodal planes arise from any place you have angular nodes.

关于节面的意义,或者节面概念的起源，让我们讲的更具体一点，节面起源于角向节点。

麻省理工公开课 - 化学原理课程节选

You can go ahead and use that equation, or you could figure it out every time, because if you know the total number of nodes, and you know the angular node number, then you know how many nodes you're going to have left.

你们可以直接用这个方程，或者每次都自己算出来，因为如果你们知道了总的节点数，又知道角向节点数，就知道剩下的节点数是多少。

麻省理工公开课 - 化学原理课程节选

Angular nodes, we're not going to have any of those, we'll have zero, l equals 0, so we have zero angular nodes.

角向节点，当然,是没有的，０个，ｌ等于０，所以是０个角向节点。

麻省理工公开课 - 化学原理课程节选