Pi bond

So our second bond is going to be a pi bond .

第二个键是π键。

And so both of these lobes together constitute a pi bond .

上下两片叶一起组成了一根π键。

Now let 's think about this first pi bond , which will be above and below the bonding axis .

让我们先来看这个π键，它在键轴的上面和下面。

Is that a sigma or a pi bond ?

这是sigma键还是π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？

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 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。

So we can kind of flip it this way this will be one pi bond , this will be another interacting between these p orbitals .

我们可以把它这样翻一下，这是一个π键，这是另外一个p轨道之间，相互作用的π键。

We 're already using it up in this pi bond here , so that means we 're limited to only two other spots on the molecule , so we have three .

我们已经把它用到这个π键里去了，所以这意味着，我们在分子里只剩下两个位置，所以一共是三个。

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 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。

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。

So if I try to rotate my2 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。

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？

Nano-particles of SiO2 form the hydrogen bond with carbonyl of PI , which changes the geometrical and electronic structure of PI , but the bond order changes a little .

SiO2纳米颗粒与PI上的羰基形成氢键，使得PI的几何结构和电子结构发生了变化，但键级基本没有变化。