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/2 So the bond order is going to be equal to 1/2, and then it will be 2 minus 2.
它的键序等于，然后乘以2减去2。
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And if we put that in our bond here, we have 1, 2, 3 bonds, plus we have one lone pair left over.
如果我们把它们放到键里，我们有1，2，3个键，还剩下一对孤对在这里。
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The price of the two-period bond is 1/2 and the price of the one-period bond is 1/.
所以两年期债券的价格是1/^2,一年期债券的价格则是1/
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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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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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Clearly, we put 2 for each bond, and now we end up having 2 remaining bonding electrons left.
显然，我们在每个键处放上两个电子，那么最后我们还剩下两个成键电子。
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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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Then minus 1/2 of 2, because we only have one bond or 2 electrons in a bond.
然后减去二的二分之一，因为我们只有一个键，一个键就是两个电子。
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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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For hydrogen our bond order is going to equal 1/2, 2 minus 0.
对于氢原子键序等于1/2，2减去。
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So if I try to rotate my 2 atoms, you see that I have to break that pi bond, because they need to be lined up so that the electron density can overlap.
如果我要试着转动两个原子，你会看到我必须要打破一个π键，因为他们需要连接起来,让那些电子能够重叠。
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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 it's going to be a sigma bond, 1s and we have oxygen 2 s p 3 and hydrogen 1 s.
它是sigma键，我们有氧2sp3和氢。
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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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/2 So this would mean the bond order is equal to 1/2, and in terms of valence electrons, how many bonding valence electrons do we have?
这意味着键序等于，对于价电子，有多少个成键价电子？
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Because if we think about wave behavior of electrons and we're forming bonds, then what we have to do is have constructive interference of 2 different electrons, right, to form a bond, we want to and together those probabilities.
如果我们考虑,电子的波动行为,并且，我们要成键的话,我们要,把，这些概率，加在一起,如果。
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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, in talking about covalent bonds, we should be able to still apply a more general definition of a chemical bond, which should tell us that the h 2 molecule is going to be lower in energy than if we looked at 2 separate hydrogen atom molecules.
那么，既然提到了共价键，我们应该还可以,给化学键下一个更普遍的定义,那就是告诉我们氢分子能量应该更低,与两个分开的氢的单原子分子相比。
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So, if we talk about dissociating h 2, we're going from the h 2 molecule, and breaking this bond right in half, so we now have two individual hydrogen atoms here.
那么，如果我们讨论的是离解氢分子，我们将从氢分子开始，使这个键断裂，一分为二，那么就得到了两个分开的氢原子。
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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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/2 PROFESSOR: Yup, it's going to be a 1 and 1/2 bond.
嗯，是1又1/2。它是1又。
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So, let's change our graph where we now have this zero point set as the two individuals hydrogen atoms, and then we see that our h 2 molecule is at the negative of the dissociation energy, or the negative what that bond strength is.
那么让我们把曲线图中的零点能改到,两个分离的氢原子处，那我们就会看到,氢分子就是负的离解能，或者负的键的强度。
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sigma2sp It's going to be a sigma bond. So, we have sigma 2 s p, carbon 2 s p. So they're two s p bonds combining.
是sigma键，我们有，碳2sp。，所以它们是两个sp键结合。
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But since in drawing Lewis structures actually, in some cases you do, you can draw a dotted line that means a 1 and 1/2 bond, but most in most cases, we just draw out both resonance structures, and the way that we say it's a resonance structure is that we put it in the brackets and we put an arrow between it.
但是由于在画路易斯结构时,其实，在某些情况下是可以的，你可以画一条虚线来表示一又二分之一键，但是在多数情况下，我们就把两个结构都画出来，而我们说这是一个共振结构的表示的方法是,把它们放在括号里，并在中间放一个双箭头。
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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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So it's along the bond axis and it's between a carbon s p 2 hybrid, and then the hydrogen is just a 1 s orbital that we're combining here.
所以它是沿着键轴方向的,而且这里是一个碳sp2杂化轨道，和一个氢的1s轨道的结合,在这里我们可以合并他们。
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These 2 are going to come together like this, and the first bond that we're going to form is going to be a sigma bond, right, so we see that here. If we're looking head on, we see they form a sigma bond.
它们两个会靠近到一起，首先会形成的是,一个sigma键，对吧，我们在这里可以看出来，我们看到它们形成一个sigma键。
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What about this second bond here sigma where we're going to have interaction of 2 p orbitals, is that sigma or pi?
那2p轨道相互作用的第二个键呢,它是，还是π？
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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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All right, so if we think about b h bond here, again, it's the sigma bond, and we're going to say it's a boron 2 s p 2 hybrid orbital interacting with a hydrogen 1 s orbital.
这可以告诉我们，为什么它倾向于周围只有6个电子，好了，考虑一下这里的BH键,同样的，它是sigma键,我们说。
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