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And so this lower level is called a bonding orbital, and it is a bonding molecular orbital.
所以能级较低的轨道叫做成键轨道，这就是成键分子轨道。
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And what you find is when you have a bonding orbital, the energy decreases compared to the atomic orbitals.
你们发现当你有个成键轨道的时候，相比原子轨道能量要降低。
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It turns out that the antibonding orbital is a little bit higher from the atomic orbital level than the bonding orbital is lower.
这证明了,反键轨道,比原子轨道高,成键轨道比原子轨道第。
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And the other thing to point out is that the energy that an anti-bonding orbital is raised by, is the same amount as a bonding orbital is lowered by.
另外一个要指出的事情是,反键轨道引起的能量升高，和成键轨道引起的能量降低是相同的。
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So again, this is an anti-bonding orbital, and what you see is that there is now less electron density between the two nuclei than there was when you had non-bonding.
同样的，这是反键轨道，你们看到当你有反键轨道的时候,两个原子核中间的电子密度更小了。
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Now, from your book as well, this is the pz's of the two atomic orbitals forming the bonding orbital.
现在，也是你们书上，这是两个pz轨道,组成的成键轨道。
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So any time I draw these molecular orbitals, I do my best, and I'm not always perfect, yet trying to make this energy different exactly the same for the anti-bonding orbital being raised, versus the bonding orbital being lowered.
所以我在画这些分子轨道的时候，虽然不是很完美，但我总是尽量,让反键轨道引起的，能量升高和成键轨道。
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I want to finish this discussion by including the anti-bonding orbital, and this is a tip for you when you're drawing your molecular orbital diagrams, any time you draw a bonding orbital, there is also an anti-bonding orbital that exists.
我想要以包含反键轨道,来结束这个讨论，告诉你们一个,画分子轨道图的小技巧，任何时候你画一个成键轨道，都会存在一个反键轨道。
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So we'll start to look at molecules and we'll see if we take two atoms and we fill in our molecular orbital and it turns out that they have more anti-bonding orbitals than bonding, that's -- a diatomic molecule we'll never see.
我们要看开始看一看分子,并且我们会发现如果我们,取两个原子并且填入分子轨道,结果是它们的反键轨道,比成键轨道更多，这就是-一个我们不会看到的二元子分子。
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And this again is what we're going to call a bonding orbital.
同样，我们叫它成键轨道。
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So any time you see a star that means an anti-bonding orbital.
任何时候你看到有个星，这意味着它是反键轨道。
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And then this means we'll have a total of sigma1s two electrons in our hydrogen molecule, so we can fill both of those into the sigma 1 s orbital, the bonding orbital. We don't have to put anything into the anti-bonding orbital, so that's great.
我们可以把这两个,都填入，轨道里去，成键轨道,我们不需要把什么放到反键轨道里去，这很好。
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So, let's start our discussion of a bonding orbital.
让我们开始来讨论成键轨道。
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So it's an Anti-bonding orbital.
这是一个反键轨道。
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So you should remember that any time we combine 2 s orbitals, what we're going to find is if we constructively interfere those two orbitals, we're going to form a bonding orbital.
你们要记住，任何时候我们组合两个2s轨道，我们会发现,如果我们把它们相长叠加，我们会得到一个成键轨道。
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So we would label our anti-bonding orbital higher in energy than our 1 s atomic orbitals.
我们应该把反键轨道标在,高于1s原子轨道能量的地方。
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So we have two electrons in our bonding orbital, but because we use the same rules to fill up molecular orbitals as we do atomic orbitals, so the Pauli exclusion principle tells us we can't have more than two electrons per orbital, so we have to go up to our anti-bonding orbital here.
所以在成键轨道上有两个电子，但因为我们用了和原子轨道时,用的相同的规则，所以Pauli不相容原理告诉我们,一个轨道上不能有两个以上的电子，所以我们需要填充到反键轨道上去。
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You might have thought before we started talking about molecular orbital theory that non-bonding was the opposite of bonding, it's not, anti-bonding is the opposite of bonding, and anti-bonding is not non-bonding.
你也许在我们讨论分子轨道之前,就想过非成键时成键的反面，它不是，反键才是成键的反面，反键不是非成键。
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When we talk about p orbitals the phase of the orbital becomes important once we talk about bonding, which hopefully you were happy to hear at the beginning of class we will get to soon.
对于ｐ轨道,当我们讨论到成键时，轨道的相位就变得非常重要了,这个我们马上就要讲到了。
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So if we name this orbital, this is an anti-bonding molecular orbital So we had bonding and now we're talking about anti-bonding.
这是反键分子轨道,我们有了成键，现在我们讨论反键。
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Also, it is cylindrically symmetric around the bonding axis, so this is how we know that it's a sigma orbital.
此外，它关于键轴是圆柱对称的，这就是为什么我们知道它是sigma轨道。
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So we're going to finish talking about molecular orbital theory, we'll switch over to discussing bonding in larger molecules, even larger than diatomic, so we'll move on to talking about valence bond theory and hybridization.
我们要结束关于分子轨道理论的讨论，转向讨论大分子的成键，比二原子分子更大的分子，我们会继续讨论价电子成键理论,和杂化。
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So that's the idea of a bonding molecular orbital.
这就是成键分子轨道的概念。
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if we move up one of our electrons into an empty p orbital, what were going to see is now we have three unpaired electrons that are ready for bonding.
教授：嗯，如果我们把其中,一个电子填入p轨道。
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Because we have paired set in a 2 s orbital, so all we're left essentially is two electrons that are available for bonding.
因为我们有一对，在2s轨道里已经配对了,所以只剩下两个电子可以用来成键。
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