In the north London neighborhood of Haringey, some young people are using their energy to do positive things.

VOA: special.2011.08.13

Positive energy is repulsive, and negative energy is attractive.

正的能量值代表斥力，负的能量值代表引力。

麻省理工公开课 - 固态化学导论课程节选

So you don't want to put in a negative energy, that's not going to help you out, you need to put in positive energy to get an electron out of the system. So that's why you'll find binding energies are always negative, and ionization energies are always going to be positive, or you could look at the equation and see it from there as well.

因为这对电离没有帮助,你需要一个正的能量,使得电子脱离这个系统,这就是为什么你会发现,结合能总是负的而电离能总是正的,或者你们看这个方程也可以发现这一点。

麻省理工公开课 - 化学原理课程节选

And that makes sense, too, because the positive three pulling on minus one has a tighter binding energy than positive one pulling on minus one.

而这也是有意义的，因为+3和-1的相互吸引,产生了比+1和-1的吸引,更强的能量。

麻省理工公开课 - 固态化学导论课程节选

One major difference between electron affinity and ionization energy is that when we talked about ionization energy, remember ionization energy always has to be positive.

电子亲和能,与电离能之间最大的不同就在于,当我们提到电离能的时候，记得电离能总是正的。

麻省理工公开课 - 化学原理课程节选

So, I've got plus twos, zooming in at high energy against a wall of positive charge.

两个高能的正电荷,在正电荷壁垒时会遇到阻力。

麻省理工公开课 - 固态化学导论课程节选

We know that binding energy is always negative, ionization energy is always positive.

我们知道结合能，总是负的，电离能总是正的。

麻省理工公开课 - 化学原理课程节选

putting all those things together, if you looked at this question again we'd get 100% on it, 0 9 that our only option here is 0. 9, and that it's not the negative, it's the positive version, because we're talking about how much energy we have to put into the system in order to eject an electron.

把这些放在一起，你们再看一下题目,大家100%都能选对，我们唯一的选择就是这个，它不是负数，它是正的，因为我们说的，是要,把电子激发出来,需要提供的能量。

麻省理工公开课 - 化学原理课程节选

So that's just a little bit of a check for yourself, and it should make sense because what you're doing is you're calculating the difference between energy levels, so you just need to flip around which you put first to end up with a positive number here, and that's a little bit of a check that you can do what yourself.

所以你们总要确保括号，离得这项是正的，这是你们自己,可以做的检查，这事很有道理的，因为你们做的是计算能量差,所以你需要调整顺序来保证一个正数，这是你们自己可以做的检查。

麻省理工公开课 - 化学原理课程节选