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A covalent bond is any time we have a pair of electrons that is shared between two different atoms.
所谓共价键就是我们有两个原子,共用一对电子。
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Let's re-draw this, so it looks a little bit neater, where we have a triple bond in the middle instead, and again, we need our negative 1 charge there.
让我们重写这个，这样看起来更整洁一点，我们有一个三键在中间，同样地，我们这里需要一个负电荷。
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So, we have this security and a ten-year bond would have twenty coupons attached, each with a date on them.
我们持有这样的证券，是十年期的债券,并附有二十张息票，每一个都有日期在上面。
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On the other hand, if we have a perfect covalence bond, we have identical equal sharing.
另一方面，如果我们有一个完美的共价键，有相同程度的电子共享。
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This is very easy molecule because we know exactly where to put them without even having to think, we only have one option, and we'll make a triple bond between the carbon and the nitrogen.
这个分子非常简单,因为我们知道应该把它们放在哪里,甚至不用去想，我们只有一个选择，我们将在碳与氮之间形成一个三键。
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So even though we see a nodal plane down the center, I just want to really point out that it's only when we have a nodal plane in the internuclear or the bond axis that we're calling that a pi orbital.
虽然在中间有个节面，我想要指出的是,只有节面在核间轴,或者键轴上时,我们才叫它π轨道。
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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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They want to get as far away from each other possible, the ideal angle is 120. But what we have here is a four-membered ring, so what angle does 90° that have to be, that bond? 90 degrees.
它们想要尽量远离彼此，最理想的是形成120°键角,但现在是个四元环,所以这键角应该多大？
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We can know this information even if we just knew that the bond was stronger, we wouldn't need to look at a graph here, because it turns out that if you have a stronger bond, -- that also means that you have a shorter bond -- those two are correlated.
我们依然可以得到上面的信息,即使我们所知道仅仅是这个键更强，我们不需要去看这个图，因为事实上如果你有一个更强的键，这也就意味着你有一个更短的键-,这两点是互相关联的。
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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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So we want to have constructive interference to form a bond, where as if we had destructive interference, we would not be forming a bond.
我们需要,相干相长来成键，如果，相干相消了，就不能成键，所以这时候。
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So we know we always want to have our systems in as low an energy as possible, so it makes sense that a bond would happen any time we got a lower energy when we combine two atoms, versus when we keep them separate.
我们知道我们总是希望使我们的系统,处于能量尽可能低的状态，因此就应该有化学键产生,一旦我们合并两个原子之后体系的能量变得更低，相较于分开时。
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We only have the one bond so the actual HF molecule is polar, it has a net dipole.
但HF中只有一根键,所以分子也是极性的而甲烷中有一个网状偶极。
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What we're going to do in forming a molecule is just bring these two orbitals close together such that now we have their nucleus, the two nuclei, at a distance apart that's equal to the bond length.
我们在形成一个分子时要做的就是,把这两个轨道放到一起,这样我们有他们的原子核，两个原子核，它们之间的距离为键长。
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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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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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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 we know every time we have two electrons, that's a bond.
我们知道每当我们有两个电子，这就是一个键。
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So we have h, then we can draw our bond as a line.
那么我们有氢，可以把我们的键画成一条线。
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Finally, I just want to say that we have also a kind of bond called an indexed bond, which is a bond whose coupons are indexed to inflation.
最后一点是,一种叫物价指数债券的债券,这种债券的票息被通胀指数化了
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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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And then we have a triple bond there because we have 3 pairs of electrons.
然后那里还有一个三键,因为我们有三对电子。
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And the last bond that we have here is a carbon-carbon bond, and this is our last p orbitals that are coming together.
最后一个键是碳碳键，这是最后一个组合的p轨道。
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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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So that's exactly what our definition of a pi bond is, so we have one sigma bond, and one pi bond.
这是我们对π键的定义，我们有一个sigma键，和一个π键。
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So, we're going to start with talking about bonding, and any time we have a chemical bond, basically what we're talking about is having two atoms where the arrangement of their nuclei and their electrons are such that the bonded atoms results in a lower energythan for the separate atoms.
那么，下面我们将从成键开始讲起，无论什么时候我们有一个化学键，基本上我们所讨论的,都是如何安排两个原子的原子核的位置,与电子的位置使得成键的两个原子,最终比分开时的能量更低。
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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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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 in sigma orbitals, you have no nodal planes along the bond axis, so if we had a nodal plane here, we'd see an area where the wave function was equal to zero.
但在sigma轨道里，沿着轴向是没有节点平面的，如果我们有个节点，我们就会看到某个地方波函数等于0。
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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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