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OK, then it says draw a single bond from each surrounding atom to the central atom, and subtract two valence electrons.
后将中心原子与其相邻原子之间,连上单键，然后减掉2个价电子。
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So if we look at its length, it's actually shorter than a single bond, but longer than a double bond.
因此如果我们看它的键长的话，它实际上比单键更短，却比双键更长。
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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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So, if we take a look at what a single bond is, and let me grab some molecules here.
如果来我们看一下单键，让我拿个分子。
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And we find the same thing for these two atoms here, it's not actually a double bond, it's somewhere between a single bond and a double bond.
而且我们发现这两个原子的情况是一样的，它其实不是一个双键，而是介于单键与双键之间的。
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And something that we'll see later on is that triple bonds, for example, are going to be stronger than a corresponding double bond or a corresponding single bond.
而我们以后还会看到三键，举例来说，应该更强，相较于相应的双键,或者相应的单键来说。
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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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So, for example, down here I wrote that it was n 2 and that it was h 2, but when I re-wrote the molecules up here, you saw that it's an h h single bond where it's a nitrogen-nitrogen triple bond.
比如，在这下面我写的是氮分子2,而这个是氢分子，但我在上面把这些分子的形式改写了，大家可以看到,这是一个氢与氢之间的单键，含一个氮与氮之间的三键。
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If we're talking about a single bond, we're talking about 2 orbitals overlapping in the internuclear axis.
如果我们讨论的是单键，我们讨论的是两个轨道,在核间轴中重叠。
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Or if we look at how strong it is, it's actually stronger than a single bond, but weaker than a double bond.
或者如果我们看键的强度的话，它实际上比单键更强，而比双键更弱。
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We would predict to see a single bond between lithium, and it turns out that's what we see.
我们可以预测在锂中会看到一个单键，而实际上确实是这样的。
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And by that what we mean is that they're absolutely identical, and it turns out that this here is not a double bond, it's not a single bond either, it's actually something in between.
这意味着它们是绝对完全相同的，实际情况应该是这不是一个双键，这也不是一个单键，而是介于两者之间的状态。
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And the bond order you get out will either be, for example, zero, which would mean that you have no bond, 5 or you could have 1, a single bond, 1 . 5, a 1 and 1/2 bond, 2, a double bond, and so on.
你得到的键序要么是比如说是零，这意味着没有键，或者你会得到1，单键1。,1又二分之一键，2，一个双键，等等等等。
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When we have just a single bond in them molecule, you have all the free rotation you want, you can just spin it around, there's nothing keeping it in place.
当我们在分子力只有一个单键时，你可以随意旋转，你可以让它转起来，没有什么东西能固定住它。
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It's a 1 and 1/2 because it's halfway between a double bond and a single bond.
是因为它介于,单键和双键中间。
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So for b 2, which is a single bond, that's 289 kilojoules per mole to break it, and it takes us more energy to break this double bond for carbon, which is 599 kilojoules per mole.
对于B2，它是单键，需要289千焦每摩尔来打破它，而对于碳双键,打破它要更多的能量，等于599千焦每摩尔。
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So, if we talked about a nitrogen-nitrogen single versus double versus triple bond, the triple bond will be the shortest and it will be the strongest.
因此，如果我们讨论的是氮与氮之间的单键,双键与三键，那么三键应该是其中最短的一个，同时也是最强的一个。
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So this is the energy of a single ionic bond.
这就是单离子键的能量。
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So, in general what we see, and this is always true if we're comparing the same atom, and in general, if we're comparing different types of molecules, but we know that a single bond is always weaker than a double bond, which is weaker than a triple bond.
通常我们会看到，这对比较相同原子来说总是正确的，通常，如果我们要比较不同种类的分子，但我们知道单键,总是要比双键弱，双键总是要比三键弱。
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Remember, every time we have two electrons that are being shared, that's a single bond.
还记得，每次我们有两个电子被共用，我们就有了一个单键。
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Yeah, we'd expect to see a single bond in hydrogen.
嗯，我们预计在氢分子里会看到一个单键。
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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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N 2 So any chemist should be able to just look at n 2 and know that it's a triple bond, but that's not something that we've learned how did to do yet, so let's go ahead and start a new topic that's going to allow us to have some sort of sense of what the valence electron configuration, which includes whether something's a single or double or a triple bond can be figured out for any given molecule.
任何一个化学家都应该能够仅仅通过看到2,就知道它有一个三键,但是我们还没学习如何做到这点，因此下面我们就开始进入一个新的主题,它将使我们能够有一定的认识,对于价电子的排布情况，包括可以对任何一个给定分子中的键是单键双键,还是三键作出判断。
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