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And a sigma bond forms any time you have two orbitals coming together and interacting on that internuclear axis.
当你把两个轨道合在一起,并在核间轴上有相互作用时,就形成了sigma键。
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So it's going to be a sigma bond, 1s and we have oxygen 2 s p 3 and hydrogen 1 s.
它是sigma键，我们有氧2sp3和氢。
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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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Any time two orbitals come straight on together in that internuclear axis, you're going to have a sigma bond.
任何时候两个轨道,在核间轴上直接到一起，你就能得到sigma键。
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If we think about that, that's a sigma bond, right, they're coming together along the nuclear axis.
如果我们考虑它的话，它是sigma键，对吧，它们沿着核轴方向靠近。
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If we have the molecule ethane, then what we're going to have first is our sigma bond that we described between the two carbons.
如果我们有乙烷分子，那我们首先有,碳碳之间的sigma键。
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So that's exactly what our definition of a pi bond is, so we have one sigma bond, and one pi bond.
这是我们对π键的定义，我们有一个sigma键，和一个π键。
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But once you have a double bond here, we have our pi bond, as well as our sigma bond.
但一旦你有了双键，我们有π键，也有sigma键。
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So if we have a single bond here, would you consider that a sigma bond or a pi bond?
如果这里有个单键，你觉得这是sigma键还是π键？
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sigma2sp It's going to be a sigma bond. So, we have sigma 2 s p, carbon 2 s p. So they're two s p bonds combining.
是sigma键，我们有，碳2sp。，所以它们是两个sp键结合。
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These 2 are going to come together like this, and the first bond that we're going to form is going to be a sigma bond, right, so we see that here. If we're looking head on, we see they form a sigma bond.
它们两个会靠近到一起，首先会形成的是,一个sigma键，对吧，我们在这里可以看出来，我们看到它们形成一个sigma键。
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It's a sigma bond, - and it's going to be -- N2sp3 no. OK, it's going to be nitrogen 2 s p 3, because it's a nitrogen atom, 1s and then hydrogen 1 s.
它是sigma键，它是-,不，OK，它是，因为这是个氮原子，然后是氢。
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If we have a double bond, we know we need to have only one sigma bond, and we're also going to have one pi bond.
如果我们有双键，我们知道我们需要一个sigma键，还需要一个π键。
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So, as they're very quietly handing out your class notes, let's think about what this bond is here, this boxed bond, is it a pi bond or a sigma bond?
在他们发讲义的同时，我们来看看这个键，方框里的这个键，它是sigma键还是π键？
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A triple bond, again is going to have one sigma bond on the internuclear axis.
一个三键，同样的也有沿着核间轴sigma键。
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So in terms of the carbon hydrogen bond, it's a sigma bond, - because we define it -- any time we are bonding to an atom, we have to keep redefining our bond axis to whatever two atoms we're talking about.
对于碳氢键，它是sigma键，因为我们定义它-,任何时候我们有原子成键，我们要重新定义键轴方向,为我们所讨论的两个原子方向。
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So in this first case here, what we're seeing is a sigma bond.
在第一个例子里，我们看到的是sigma键。
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In contrast, if we talk about a double bond, what we're now talking about is having both a sigma bond and also one pi bond. And I apologize, I intended to set this up right before class, but that didn't happen today.
相反，如果我们讨论一个双键，我们现在讨论的是,一个sigma键和π键，抱歉，我应该在课前就把这个装好的，今天没装好。
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PROFESSOR: Yup, it's a sigma bond.
教授：它是sigma键。
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So if we go ahead and name this bond, what we're going to name it is sigma, - because that's the -- basically the shape of the bond or that's how our bond is coming together.
所以如果我们继续并且命名这一键，就是我们要命名的这个键，因为这是-,基本上键的形状,或者这就是键是怎么到一起的。
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So would you expect this to be a pi bond or a sigma bond her PROFESSOR: OK, so I'm hearing some mixed answers.
你们觉得这是一个π键还是sigma键？,我听到有不同的答案。
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All right, so if we think about b h bond here, again, it's the sigma bond, and we're going to say it's a boron 2 s p 2 hybrid orbital interacting with a hydrogen 1 s orbital.
这可以告诉我们，为什么它倾向于周围只有6个电子，好了，考虑一下这里的BH键,同样的，它是sigma键,我们说。
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The reason that it's a sigma bond is sp3 because the s p 3 hybrid orbital is directly interacting with the 1 s orbital of the hydrogen atom, and that's going to happen on the internuclear axis, they're just coming together.
它是sigma键的原因,是因为,杂化轨道直接和氢原子1s轨道相互作用，它们作用发生在核间轴上，它们会到一起。
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PROFESSOR: Right, it's a sigma bond.
对，这是sigma键。
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It turns out that it's a sigma bond.
实际上它是sigma键。
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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。
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What about this second bond here sigma where we're going to have interaction of 2 p orbitals, is that sigma or pi?
那2p轨道相互作用的第二个键呢,它是，还是π？
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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。
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So in the first case of this first bond here that I've put in a square, what type of a bond is this, is the sigma or pi?
在这第一个键里,我用方框把它标出来了，这个键是什么类型的，sigma还是π？
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But keep in mind sigma orbitals have no nodal planes along the bond axis.
但记住sigma轨道沿着,键轴方向是没有节点的。
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