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And I am going to superscript it molecular orbital, and this upper one, to indicate that it's antibonding, has the asterisk.
我将给分子轨道加上标，这个上标，表示反键轨道，有一个星号。
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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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So, we'll start today talking about the two kinds of molecular orbitals, we can talk about bonding or anti-bonding orbitals.
今天我们先来,讨论两种分子轨道，我们要讨论成键和反键轨道。
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You can certainly hit Enter but as we saw-- seen that very quickly makes a mess of your code and such and so backslash N is new line.
你也可以敲回车键-,但是会让你的代码看起来乱七八糟,反斜杠n就是换行符。
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And because of the way those antibonding orbitals are stacked, the two electrons go one each into those antibonding.
因为这样,反键轨道被堆积了，这两个电子都填到各自的反键轨道。
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All right, so the bonding order, you're correct, should be 2, if we subtract the number of bonding minus anti-bonding electrons and take that in 1/2.
好，你们是对的，键序为，如果我们用成键数,减去反键数除以2。
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so you can see that there is going to be two sets in antibonding, three sets in bonding for a net of one, giving us the single bond.
因此你能看到,反键轨道上有两组，三组成键，得到一组净成键，所以成的是单键。
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The way that we can figure this out is using something called bond order, and bond order is equal to 1/2 times the number of bonding electrons, minus the number of anti-bonding electrons.
我们可以用叫做,键序的概念来弄明白它，键序等于1/2乘以成键电子,数目减去反键电子数目。
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And this one, just for completeness, is what the antibonding orbital would look like.
然而这个，只是为了其完全性，把反键轨道也表示出来。
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So specifically, what we do associate them instead is within molecular orbitals, and what we say is that they can be either in bonding or anti-bonding orbitals.
特别的，我们把它们和,分子轨道相联系起来，我们说它们可以成为,成键轨道或者反键轨道。
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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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So for the bond order we want to take 1/2 of the total number of bonding electrons, so that's going to be 4 minus anti-bonding is 4, so we end up getting a bond order that's equal to 0.
键序等于1/2乘以,总的成键电子数，也就是4，减去反键电子数，也就是4。,所以最后得到键序为0。
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Here is the antibonding and here is the bonding.
这是反键轨道，这是成键轨道。
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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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And then the antibonding which we don't care about.
然后他们的反键轨道我们不去管了。
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s plus 1s gives you this oval ellipsoid which is the bonding, and here are the antibonding, and then these are the energy levels that I have been drawing for you.
s和1s上两个电子组成的键合电子成椭圆形,这是成键，这是反键电子，这些是刚刚已经画过的能级,我也给你们画了。
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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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We can also talk about anti-bonding orbitals where we have destructive interference.
我们也可以讨论,相消干涉的反键轨道。
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PROFESSOR: All right, what about anti-bonding?
嗯，那反键呢？
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So it's an Anti-bonding orbital.
这是一个反键轨道。
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So it helps us predict, will we see this, for example, h 2, which we're going to be about to do, we'll see is stabilized because it has more bonding than anti-bonding.
这帮助我们预测，我们等会会看到，比如H2O，我们等会要讲到，我们会看到它更稳定是,因为成键比反键更多。
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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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And what we see here is now when we're combining the p, we have our 2 p x and our 2 p y orbitals that are lower in energy, and then our pi anti-bonding orbitals that are higher in energy.
这里我们看到,当我们结合p轨道时，在低能处我们有,2px和2py轨道，π反键轨道在更高的能级处。
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So you can see that this is non-bonding, this is even worse than non-bonding, it's anti-bonding, because we're actually getting rid of electron density between the two nuclei.
所以你可以看到这是不成键的，它甚至比不成键还糟糕，它是反键，因为我们实际上是去掉了,两个原子核之间的电子。
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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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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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And this one here, because it is at a higher energy is called antibonding molecular orbital.
这里的这个，因为处在一个较高的能级,被叫做反键分子轨道能级。
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So we know that it's 1, because we have 1, 2, 3, 4 bonding, minus 2 anti-bonding, and 1/2 of that is a bond order of 1.
我们知道它是，因为我们有1，2，3，4个成键，减去2个反键，它的一半就是键序为1。
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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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