这就是成键分子轨道的概念。
这是成键和反键。
各类有机磷化合物的电子结构与成键。
The electronic structure and bonding of various phosphorus compounds.
这是反键分子轨道，我们有了成键，现在我们讨论反键。
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.
本质上就是由于，未配对电子配对导致的成键。
Essentially what you have is bonds resulting from the pairing of unpaired electrons.
你应该了解考虑成键时，去考虑内层电子，是毫无意义的。
You can see that there is no value in studying inner shell electrons to ask questions about bonding.
在成键时，会释放大量能量，这比补偿激发电子，的能量要多。
We're going to release a lot of energy for bonding, it's going to more than make up for the fact that we actually had to spend some energy to promote that electron.
我们现在可以考虑，怎么在价电子成键理论中描述这个键。
So, we can think about now how do we describe this bond in valence bond theory.
所以能级较低的轨道叫做成键轨道，这就是成键分子轨道。
And so this lower level is called a bonding orbital, and it is a bonding molecular orbital.
在这之前我们要引入价电子成键理论，和杂化轨道的概念。
And to do this we're going to introduce valence bond theory, and the idea of hybridization of orbitals.
任何时候如果你有两个原子成键，键轴就是它们成键的方向。
So any time you have two atoms bonding, the bond axis is just the axis that they're bonding along.
那么我们有十八个电子，下一步要做的是判断,我们有多少个成键电子。
So we have 18 electrons, and the next thing that we need to figure out is how many bonding electrons we have.
记住，这在我们讨论到，成键的时候很重要，现在你们还不用太多的考虑它。
Remember, that's going to become important when we talk about bonding, we don't need to worry about it too much right now.
体温下聚合物和水之间的化学键变弱，聚合物分子彼此更易于成键。
At body temperature, the polymer-water bonds weaken, and the polymer molecules prefer to bond with each other.
但是，在周五我们,会用一种新的办法来讨论,不止两个原子的分子的成键。
However, on Friday we will use a different approach so we can talkabout bonding within atoms that have more than two atoms, molecules with more than two atoms.
我们知道是两个原子核之间的，电子密度保持两个原子在一起成键的。
And we know that it's electron density between the nuclei that holds two atoms together in a bond.
我们现在可以考虑成键了，现在我们有4个等价的轨道，每个上面有1个电子。
So we can think about now doing bonding, and now we have four equal orbitals with one electronic each.
因为我们有一对，在2s轨道里已经配对了，所以只剩下两个电子可以用来成键。
Because we have paired set in a 2 s orbital, so all we're left essentially is two electrons that are available for bonding.
我们这里一共有四个氢原子成键，我们可以考虑怎么来-，描述碳碳键。
So we can have four total hydrogens bonding here, - and we can think about how to describe these carbon - carbon bonds.
目前为止任何时候我们尝试要，描述分子内的成键，我们都是利用Lewis结构。
So far we've exclusively been using Lewis structures any time we've tried to describe bonding within molecules.
我们还有6个地方可以供氢原子成键，我们可以继续把这些电子填充进去。
We also have six spots available to form hydrogen bonds, so we can go ahead and fill in those electrons as well.
因为第五步要做的是将我们的成键电子填在这，所以我们开始在每个键处填上两个电子。
Because step five is that we need to fill in our bonding electrons, and we start it with filling in two electrons per 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。
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.
如果我们考虑有六个氢原子，每个都会合起来，碳杂化轨道成键，每个氢的1s轨道。
And if we think about the six hydrogens, now each of those are going to bind by combining one of the carbon hybrid orbitals to a 1 s orbital of hydrogen.
那么你就会有一个碳原子在中心，三个氢原子围绕着它，那么它只能再和一个原子成键。
Then what you have is a carbon in the middle with three hydrogens around it, and then it can only be bonded to one other thing.
这里三角形是因为,我们有3个原子核中心原子成键，如果你画它，它就是金字塔形的。
So it's trigonal because we have these three atoms that are bound to the central atom here, and if you picture it, it's actually shaped like a pyramid.
而第四步需要判断，我们有多少个成键电子，那么我们有十六减十，也就是六个成键电子。
And step four is going to have us figure out how many bonding electrons we have, so we have 16 minus 10, is going to be 6 bonding electrons.
但它们在预测分子内，成键时不总是正确的，这是因为Lewis结构，实际上不是基于量子力学的。
But they're not accurate all the time in predicting bonding within molecules, and the reason for this is because Lewis structures are not, in fact, based on quantum mechanics.
对，也是四个，我们从十个价电子开始，只用了六个来成键，因此我们还剩下四个，它们将成为孤对电子。
Yeah, so also 4. We started with 10 valence electrons, we used up 6 of those as bonding electrons, so we have 4 left, which will be lone pair electrons.
分析了石墨微晶结构与成键特征，研究了石墨微晶中边缘碳原子与基平面碳原子的电化学特性。
The electrochemical characteristics of carbon atoms on the edge and basal plane were determined by analyzing structure of graphite crystal and bond of different carbon atoms.
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