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And the technique is called, watch because this is a six-letter initialization, linear combination of atomic orbitals LCAO-MO into molecular orbital, LCAO-MO.
这项技术是，一个6字母初始设定，原子轨道的线性叠加,成分子轨道。
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So any time in a molecular orbital diagram you draw in orbitals, you need to draw the corresponding molecular orbitals.
任何时候你在分子轨道图里画轨道，你都要画出相对应的分子轨道。
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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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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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So we can go ahead and name our molecular orbital, just like we know how to name our atomic orbitals.
我们可以继续命名分子轨道，就想我们知道如何命名原子轨道一样。
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Right, we had one from each atom, so that means we need a total of two in our molecular orbital.
对吧，每个原子有一个电子，这意味着在分子轨道里我们一共需要两个电子。
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So, in this case, we're just drawing the molecular orbital diagram for the valence electrons, so we have three for each.
所以在这个例子里面，我们只需要画出,价电子的分子轨道图，所以每个有3个电子。
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So, I think we have these molecular orbital energies down, so let's move on to talking about more complex molecules.
分子轨道能量就说到这里，让我们继续来讨论一下更复杂的分子。
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Whereas in molecular orbital theory, what I'm telling you is instead we understand that the electrons are spread all over the molecule, they're not just associated with a single atom or a single bond.
而在分子轨道理论里，我要告诉你们的时,我们任为电子分布在整个分子中,它们不仅仅是和,一个原子或者一个键有关。
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All right, so we can now see a little bit of what the power of molecular orbital theory is in predicting what kind of bonds we're going to see in molecules, or whether or not we'll see this bonding occur at all.
好了，我们已经可以看到一点,分子轨道理论在预测分子中,所成的键或者分子，能不能成键方面的能力了。
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So when you go ahead and draw these on your problem-sets or on your exams, it's a good idea to put these dashed lines in, both for you and for people reading it to see exactly where your molecular orbitals are coming from.
所以当你在做课后题,或者考试的时候要画这些图时，最好把这些虚线放进去，既方便你自己也方便别人知道,这些分子轨道是从哪里来的。
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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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If we overlay what the actual molecular orbital is on top of it, what you see is that in the center you end up cancelling out the wave function entirely.
如果我们把真实的分子轨道覆盖在上面，你可以看到中间的,波函数是完全抵消掉了。
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So, we'll start by taking a look at constructive interference, and another way to explain this is just to say again, molecular orbitals are a linear combination of atomic orbitals.
我们先来看一看相长干涉，另外一个解释它的方法就是说，分子轨道是原子轨道的组合。
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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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OK PROFESSOR: Valence electrons. OK, sometimes you're going to be asked to draw a molecular orbital diagram where you're asked to include all electrons, and sometimes it will specifically say only include valence electrons.
教授：价电子，有时候你画一幅分子轨道图,有时候要求你画出所有的电子，有时候特别要求,只包括价电子。
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So, let's draw in our electrons there, so we have our two electrons now in the molecular orbital.
让我们把电子画在这里，我们现在有两个电子在分子轨道里。
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Here is the atomic nitrogen, here is the atomic nitrogen and these are the orbitals of molecular nitrogen.
这是氮原子，这是氮原子,然后这是氮气的分子轨道。
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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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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 if we have constructive interference between the two, what we're going to see is our molecular orbital looks something like this.
如果两者是相干干涉，我们看到分子轨道,看起来是这个样子的。
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So it's going to be favorable for the electrons instead to go to that lower energy state and be within the molecular orbital.
所以对于电子来说,更倾向于能量更低的轨道,呆在分子轨道里。
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What we've seen is we have a net lowering of energy of the molecule versus the individual atoms.
分子轨道对于单个原子轨道来说,我们可以看到的是一个净的能量降低。
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So, if we have two atomic orbitals coming together from two different atoms and they combine, what we end up forming is a molecular orbital.
如果我们有两个,不同原子的原子轨道,而且它们组合到一起，我们最后就能得到一个分子轨道。
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So, this means we have a total of six electrons that we need to put into molecular orbitals.
这意味着我们一共有,6个电子要放进分子轨道。
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So, if we look at the molecular orbital, that's actually going to be lower in energy than either of the two atomic orbitals.
如果我们看分子轨道的话，它实际上要比,两个原子轨道都要低。
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It might not have any electrons in it, but it still exists, so you need to draw these into your molecular orbital diagram.
也许它里面没有电子，但它是存在的，所以你需要在分子轨道图里画出来。
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Molecular orbital theory, even at this very basic level, allowed us to predict that no, we're not going to see a true bond here, a strong bond.
即使在最基础的层次，分子轨道理论预计，我们不会看到一个键，一个强的键，。
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So we're going to limit in our discussion in 511-1 for molecular orbital theory to diatomic molecules.
我们在这个课堂上对分子轨道1,理论的讨论仅限于双原子分子。
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