The nitrogen atoms of amines have what chemists call a lone pair of electrons, and it is this which attaches each amine molecule to the nanotube.

胺上的氮原子存在着一种电子对，化学家们管这叫孤对电子（译者：嘿嘿~高中知识竟然还未忘记），而正是这些孤对电子把胺分子牢牢绑在纳米管上。

youdao

So, which atom is in need of those lone pair electrons?

那么，哪个原子需要这对孤对电子呢？

youdao

So, if we want to figure out the formal charge on the carbon, we need to take the number of valence electrons, so that's 4. We need to subtract the lone pair, what number is that? It's 2.

如果我们想算出碳原子的形式电荷，我们需要将价电子的个数，也就是四，减去孤对电子的个数，它是多少？是二。

youdao

For the carbon, we start with 4 valence electrons, we have 0 lone pair electrons minus 4, and we end up with a formal charge of 0.

对于碳，我们从四个价电子开始，我们有零个孤对电子，再减去四，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

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