If these bonds were all completely of equal distance apart, whether is was a lone pair or bonding electrons, 5° the angles would be 109 . 5 degrees.

如果不管它是孤对，还是成键，它们等距分开的话，键角是109。

麻省理工公开课 - 化学原理课程节选

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.

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。

麻省理工公开课 - 化学原理课程节选

That's because you have to satisfy this base pair matching in order to have hydrogen bonding in each of the struts of the ladder in order to form a stable structure.

NA双链要满足互补配对原则,以使碱基对之间,形成氢键,从而形成稳定的双链结构

耶鲁公开课 - 生物医学工程探索课程节选

So if we take a look at nitrogen here, what you'll notice is we have thre available for bonding, - and we already have our lone pair -- one of our orbitals is already filled up.

如果我们看一下氮原子，我们注意到我们可以成3个键，我们已经有一个孤对-,其中的一个轨道已经被填满了。

麻省理工公开课 - 化学原理课程节选

For the sulfur, we start off with 6 valence electrons, minus 4 lone pair electrons, minus 2, taking in account our bonding electrons, so we end up with a formal charge of 0.

对于硫，我们从六个价电子开始，减去四个孤对电子，再减去二，算上我们的成键电子，因此最终我们有零个形式电荷。

麻省理工公开课 - 化学原理课程节选

That's what we call when we have three bonding atoms and one lone pair.

这是当我们有3个成键电子,和一个孤对时这样称它。

麻省理工公开课 - 化学原理课程节选

So what we see is on ammonia here, 107 we know that it's less than a 109 . 5, it's actually 107, so it's less than a 109 . 5, because of that lone pair pushing down in the bonding electrons.

我们看到在氨分子里，我们知道它比１０９．５要小，它是，所以比109。5要小，因为孤对会把成键电子向下推。

麻省理工公开课 - 化学原理课程节选