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So any time in a molecular orbital diagram you draw in orbitals, you need to draw the corresponding molecular orbitals.
任何时候你在分子轨道图里画轨道，你都要画出相对应的分子轨道。
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OK PROFESSOR: Valence electrons. OK, sometimes you're going to be asked to draw a molecular orbital diagram where you're asked to include all electrons, and sometimes it will specifically say only include valence electrons.
教授：价电子，有时候你画一幅分子轨道图,有时候要求你画出所有的电子，有时候特别要求,只包括价电子。
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We can even understand it on a molecular or cellular level now.
如今我们已经能从,分子和细胞水平对机体进行研究
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This is sigma star with the antibonding orbital that came from 1s, and it is a molecular orbital.
这是sigma星，来自于1s的反键轨道,它是一个分子轨道。
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And as I will explain in a second there are many reasons why this sense hasn't really been elucidated at the molecular level.
难以真正从分子学的角度阐明,这种感官的原因是多方面的,有关这一点,稍后我会另行解释。
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So, if we have two atomic orbitals coming together from two different atoms and they combine, what we end up forming is a molecular orbital.
如果我们有两个,不同原子的原子轨道,而且它们组合到一起，我们最后就能得到一个分子轨道。
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But now we're talking not about an atomic wave function, we're talking about a molecular wave function.
但现在我们不是讨论原子的波函数，我们讨论的是分子的波函数。
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And the technique is called, watch because this is a six-letter initialization, linear combination of atomic orbitals LCAO-MO into molecular orbital, LCAO-MO.
这项技术是，一个6字母初始设定，原子轨道的线性叠加,成分子轨道。
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And so this lower level is called a bonding orbital, and it is a bonding molecular orbital.
所以能级较低的轨道叫做成键轨道，这就是成键分子轨道。
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So, we'll start by taking a look at constructive interference, and another way to explain this is just to say again, molecular orbitals are a linear combination of atomic orbitals.
我们先来看一看相长干涉，另外一个解释它的方法就是说，分子轨道是原子轨道的组合。
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And this one here, because it is at a higher energy is called antibonding molecular orbital.
这里的这个，因为处在一个较高的能级,被叫做反键分子轨道能级。
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If I look at a homonuclear molecule such as molecular hydrogen, this is perfect sharing.
如果我用这个测量表测氢分子,完全平均共价的分子。
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I want to finish this discussion by including the anti-bonding orbital, and this is a tip for you when you're drawing your molecular orbital diagrams, any time you draw a bonding orbital, there is also an anti-bonding orbital that exists.
我想要以包含反键轨道,来结束这个讨论，告诉你们一个,画分子轨道图的小技巧，任何时候你画一个成键轨道，都会存在一个反键轨道。
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This diagram at the top here is a very familiar one to most of you, it's sometimes called the central dogma of molecular biology.
顶部这个示意图,对大家来说都非常熟悉,这叫做分子生物学的中心法则
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This means we need a total of eight electrons in our molecular orbitals.
这意味着分子轨道里,一共有八个点子。
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The 1 s just comes from the fact that the molecular orbital is a combination of two 1 s atomic orbitals.
是因为分子轨道是两个,1s原子轨道的组合。
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So that's the idea of a bonding molecular orbital.
这就是成键分子轨道的概念。
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So maybe you could figure out how to use what we know about molecular biology, to engineer a new virus that's still immunogenic, but not pathogenic any longer.
也许你能指出如何使用,分子生物学的有关知识,来设计一个既能产生免疫性,但又不再有致病性的新病毒
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It's really been a powerful tool in molecular biology because I might have a very small copy of a gene that I'm interested in and I can make enough copies that I can start to do something else with it.
这确实是分子生物学的一项利器,因为我可能只有,很少量的感兴趣的基因拷贝,而我可以马上制造出足够数量的复制品,能使我用作其他用途
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Now the bases, and you don't need to memorize the structures of these I'm going - I'm describing the whole molecule to you in its molecular detail and then we're going to simplify it down to a version that we can talk about more easily.
现在讲碱基,你不需要记住这些结构,我将给你们详述整个分子,的结构细节,然后我们把它简化为一个模板,使我们更容易讨论
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And what I want to point out that we just figured out for molecular orbital theory, is that o 2 is a biradical, because remember, the definition of a radical is when we have an unpaired electron.
我要指出的是,我们刚利用分子轨道理论，指导了O2是二价自由基，因为记住，自由基的定义是,有个未配对的电子。
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And there's actually a way that we can make predictions here, and what I'll tell you is molecular orbital theory predicts that h e 2 does not exist because it's not stabilized in terms of forming the molecule.
其实我们有一种办法可以做出预测，我要告诉你们的是分子轨道,理论预测He2不存在,因为它形成分子不稳定。
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So again, we can name these molecular orbitals and these we're going to call also to point out there is now a bond axis along this nodal plane, which is something we didn't see before when we were combining the s orbitals.
同样的，我们可以,命名这些分子轨道,这些轨道叫做-同样要指出的是,现在沿着键轴是一个节点面，这是我们讨论s轨道的时候,从没有看到过的。
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So we can draw that for 1 s a, we can also draw it for 1 s b, and what I'm saying for the molecular wave function is that we have the interference between the two, and we have a constructive interference, so we end up adding these two wave functions together.
所以我们可以对1sa画出它来，我们也可以对1sb画出它来，对于分子波函数我要说的是,它们两者之间会干涉，这里我们有相长干涉，所以我们得到的是波两个波函数加起来。
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We don't need to really talk about all the molecular detail in order to completely describe a DNA or an RNA molecule because these structures repeat themselves.
我们在完整的描述一个DNA或RNA时,不需要说明,分子上的每一个细节,因为它们的结构都是重复的
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