So, today we're moving on, we're talking about Lewis structures.
那么，今天我们接着讲，继续讨论路易斯结构。
We remember that Lewis structures are an idea that are pre-quantum mechanics.
我们记得路易斯结构是一个，早于量子力学的概念。
So, to do this, what I'm going to do is introduce the topic of Lewis structures.
那么，了做到这一点，我将开始介绍,路易斯结构。
All right. So let's try one more example of drawing Lewis structures before we talk about formal charge.
好，让我们在讲形式电荷之前，再给一个例子画一下路易斯结构。
So far we've exclusively been using Lewis structures any time we've tried to describe bonding within molecules.
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, when we talked about Lewis structures, we actually assigned electrons to individual atoms or to individual bonds.
当我们讨论Lewis结构时，我们把每个电子指派到，各个原子或键上去。
So now that we have enough practice drawing Lewis structures let's talk about actually figuring out this formal charge.
那么现在我们已经做了足够多的画路易斯结构的练习，让我们来讨论一下如何得出形式电荷。
This was something we could not predict using Lewis structures, but we can predict using MO theory that we have a radical species here.
这是我们从Lewis结构里不能预测的，但我们可以用分子轨道理论,预测自由基。
So that's a really important type of an application that we can use MO theory for that we weren't able to do with our Lewis structures.
这是MO理论，在Lewis结构，不能用时的，非常重要的应用。
So we'll talk specifically about drawing Lewis structures and then about formal charge and resonance, which are within Lewis structures.
因此我们会专门讲一讲，如何来画路易斯结构，然后再讨论形式电荷与共振论，它们也属于路易斯结构的范畴。
So, these are the different ways that we can actually go ahead and use formal charge when we're choosing between different types of Lewis structures.
那么，这些就是在我们需要在,不同的路易斯结构之间做选择的时候,我们如何用形式电荷来进行判断的各种方法。
And I mean this means way past all the chemistry they've taken, they're now graduate students or they're now professors, and they're still writing out Lewis structures.
我想说的是这意味着尽管他们早就学完了所有的化学，他们现在都已经是研究生甚至是教授了，但他们依然在不断地写路易斯结构。
So in terms of remaining valence electrons we have 12, so we can finish off each of our Lewis structures, so that's our first structure there, and our second structure there.
那么关于剩下的价电子，我们有十二个，因此我们可以完成这两个路易斯结构了，那么这是我们的第一个结构，而那是我们的第二个结构。
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.
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。
And the last thing we do for any of our structures to check them and figure out are these valid or not valid, are these good Lewis structures is to check the formal charge.
而为了检验任何一个结构是否有效，看它们是不是好的路易斯结构，我们要做的最后一件事就是检查形式电荷。
So, we can also get into a case where we have similar values in terms of absolute values of formal charge between two different molecules we're deciding between in their Lewis structures.
我们还可能遇到另外一种情况，那就是在我们需要进行，选择的两种路易斯结构中，形式电荷具有相似的绝对值。
And the idea is that when you do these Lewis dot structures, we're representing electrons with dots, which we'll see in a minute, and each dot is going to represent a valence electron.
而当你遇到这些路易斯点结构时，我们会将电子用点来表示，我们马上就会看到，每个点都代表了一个价电子。
Acetylation between alcohol and benzoyl oxide was carried out using ZnBr_2 as a Lewis acid catalyst in solvent-free condition. Some structures were characterized by NMR and IR.
以溴化锌为催化剂，在无溶剂条件下实现了醇与苯甲酸酐的酰化反应，部分产物经NMR和IR表征。
Acetylation between alcohol and benzoyl oxide was carried out using ZnBr_2 as a Lewis acid catalyst in solvent-free condition. Some structures were characterized by NMR and IR.
以溴化锌为催化剂，在无溶剂条件下实现了醇与苯甲酸酐的酰化反应，部分产物经NMR和IR表征。
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