-
This is because most fraternities and sororities are named after a series of Greek letters, such as Alpha Delta Pi or Sigma Phi.
VOA: special.2009.09.25
-
So let's fill it out in this way, 2p keeping in mind that we're going to fill sigma out the pi 2 p's before the sigma.
让我们这样填上去，记住我们先填π,轨道再填。
-
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。
-
sigma That is one pi orbital. There is one sigma, one pi and there is a second pi, and that is how we are getting the triple bond.
那是一个pi轨道，有一个，一个pi，还有第二个pi轨道，这就是我们如何得到三线态的。
-
Again, we're going to take the linear combination of those p atomic orbitals and make what are called pi or some more sigma molecular orbitals.
同样的，我们需要得到,原子p轨道的线性组合,然后组成我们所说的,π分子轨道或者sigma分子轨道。
-
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。
-
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？
-
So z equals 7 -- this is the cut-off where, in fact, the sigma orbital is going to be higher in energy than the pi 2 p orbitals.
所以z等于7-这是分界点，实际上，sigma轨道能量,要比π2p轨道高。
-
Another thing I want to point out about every sigma orbital that you see, and it will make more sense when we contrast it with pi orbitals later.
另外一个我要指出的事情就是,关于每个sigma轨道你能看到,当我们把它和π轨道对比的时候会看的更清楚。
-
So let's think about how we can classify single and double and triple bonds, which is what we're really used to dealing with in terms of these sigma bonds and these pi bonds.
让我们想想怎么来分类单键双键,和三键，这在我们在考虑sigma键,和π键是很有用的。
-
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？
-
So would you expect this to be a pi bond or a sigma bond her PROFESSOR: OK, so I'm hearing some mixed answers.
你们觉得这是一个π键还是sigma键？,我听到有不同的答案。
-
So this is very similar to what we saw i n terms of sigma orbitals and pi orbitals.
这和我们在sigma轨道,和π轨道中看到的很像。
-
So in the first case of this first bond here that I've put in a square, what type of a bond is this, is the sigma or pi?
在这第一个键里,我用方框把它标出来了，这个键是什么类型的，sigma还是π？
-
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。
-
So, as they're very quietly handing out your class notes, let's think about what this bond is here, this boxed bond, is it a pi bond or a sigma bond?
在他们发讲义的同时，我们来看看这个键，方框里的这个键，它是sigma键还是π键？
-
So some p orbitals form pi molecular orbitals, and some form sigma p orbitals.
有些p轨道会形成π分子轨道，有些会形成p轨道。
-
Do you predict that this will be a sigma or a pi orbital?
你们认为这是sigma轨道还是π轨道？
-
So that's why these are pi orbitals instead of sigma orbitals.
这就是为什么它们是π轨道而不是sigma轨道。
-
z And what you need to remember is if the z 8 is equal to eight or greater, such as oxygen being the cut-off point, this sigma 2 p orbital is actually lower in energy than the pi 2 p orbitals, the molecular orbitals.
你们要记住如果,等于或者大于，就像O是分界点，这时sigma2p轨道,比π2p轨道能量更低。
-
Would this be a sigma or a pi?
这是sigma还是π？
-
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。
-
We want to discuss sigma bonds and pi bonds.
我们要讨论sigma键和π键。
-
Is that a sigma or a pi bond?
这是sigma键还是π键？
-
Is this pi or sigma?
它是sigma键吗？
-
All right, so what we see here is we have our sigma bond that's along the internuclear axis here, but we also have a pi bond, because each of these atoms now has electrons in it's in a p orbital, so we're going to overlap of electron density above and below the bond.
这里我们看到sigma键,是沿着核间轴的，但我们还有一个π键，因为每个原子的p轨道上,都有电子，所以电子密度在键的上面,和下面都有电子密度交叠。
应用推荐