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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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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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98 And so the double bond is 498.
双键是。
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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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So let's take a look at what actually happens if we're talking about a carbon-carbon double bond, we're going to have a double bond.
让我们来看一看碳碳双键的情况,例如在乙烷里，我们有个双键。
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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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So in order to rotate a double bond, you have to actually break the pi bond, so essentially what you're doing is breaking the double bond.
为了能够旋转双键，你必须打破一个π键，本质上我们要做的就是打破双键。
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All right, so let's think of a more complicated example of having a double bond, and maybe a more interesting example, and this is talking about benzene.
好了，让我们来看关于双键的,一个更复杂的例子，也许是更有趣的例子，我们要讨论苯环。
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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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So it's very important to be keeping in mind that any time you see a double bond, you have a pi bond there, so you're not going to see any rotation around the bond axis.
所以你们要记住,任何时候你们看到一个双键，这里面有π键，你们不会看到关于键轴的任何转动。
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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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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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So really, you can not ever rotate a double bond, it makes your molecule very rigid.
实际上，你不能转动一个双键，它使得你的分子很坚固。
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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 I show that here, so in green, you have what's called a carboxcylic acid group, a c o o h, which gets converted by s o c l 2 to a c double bond o c l or an acid chloride.
我在这里用绿色表示，我们所说的羧酸族化合物，碳，氧，氧，氢，它被亚硫酰氯转化为,一个碳氧双键与碳氯单键组成的酰氯。
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So it's very important that the double bond locks it in a particular conformation.
所以双键把它们锁定在某一特定形状,是十分重要的。
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But once you have a double bond here, we have our pi bond, as well as our sigma bond.
但一旦你有了双键，我们有π键，也有sigma键。
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This is incredibly important because if you picture having a double bond in a very large molecule, you could have all sorts of other atoms off this way and all sorts of other atoms off this way, and you can picture the shape would be very different if you have one confirmation versus another confirmation.
这是十分重要的,因为如果你想象在一个大分子里有一个双键，你可以在这里有各种各样的其它原子,在这里也有各种各样的其它原子，你可以想象一个构型,和另外一个构型之间的形状差别是非常大的。
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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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In this case we have a double bond between a and b, and in this case we have it between b and c.
在这种情况下，我们在，A，与，B，之间有一个双键，而在这种情况下，双键在，B，与，C，之间。
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If we have a double bond, we know we need to have only one sigma bond, and we're also going to have one pi bond.
如果我们有双键，我们知道我们需要一个sigma键，还需要一个π键。
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In contrast, if we talk about a double bond, what we're now talking about is having both a sigma bond and also one pi bond. And I apologize, I intended to set this up right before class, but that didn't happen today.
相反，如果我们讨论一个双键，我们现在讨论的是,一个sigma键和π键，抱歉，我应该在课前就把这个装好的，今天没装好。
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So that's two of our types of bonds in benzene, and we have one type left, that's going to actually be the double bond or the pi bond that So we can have one bond here between this carbon's p orbital and this carbon's p orbital.
这就是苯环里的两种键，我们还剩一种，那就是这些p轨道之间，形成的双键或者π键,我们可以在这个碳的p轨道,和这个碳的p轨道之间有个键。
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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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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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