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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 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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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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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 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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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 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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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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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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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, 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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I am going to sum up the atomic orbitals that go into the molecular orbital, and they are going to have some coefficients.
我准备将原子轨道组合起来,进行分子轨道计算，这个过程还需添加一些系数。
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All right. So, today we're going to be talking about molecular orbital theory, but first I wanted to just mention, in case some of you didn't hear what the Nobel Prize was this morning, and this was in chemistry, it went to three different chemists.
好的，今天我们要讲的是,分子轨道理论，但首先我要说，以免有些同学没有听到,今天早上的诺贝尔奖，这是化学奖，它颁给了3个不同的化学家。
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So any time that you're drawing these molecular orbital diagrams you want to keep in mind that the number of electrons that you have in atomic orbitals, you need to add those together and put that many electrons into your molecule.
任何时候当你们画分子轨道图时,你们要记住,原子轨道里的电子数，你要把它们加在一起,并放到分子轨道里去。
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And again, I want to point out that a molecular orbital, we can also call that a wave function, they're the same thing.
同样，我要指出的是,一个分子轨道，我们也可以叫它波函数，这是一件事情。
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So in molecular orbital theory, what we did was we named orbitals based on their symmetry.
在分子轨道理论中，我们基于轨道的对称性给它们命名。
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Pi orbitals are a molecular orbital that have a nodal plane through the bond axis.
轨道是沿着键轴,有节面的分子轨道。
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It's the same thing with molecules a molecular wave function just means a molecular orbital.
这对于分子也是一样,分子波函数就意味着分子轨道。
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