So, if you can't immediately know, and you don't all have periodic tables in front of you, so that's fine, but if you have a periodic table in front of you, you need to be able to count valence electrons, so work on that if it doesn't come naturally to you in terms of figuring that out.

如果你不能马上想到，而且你手上没有周期表，那还好，但如果你面前有一张周期表，那你就得具备从中查出价电子个数的能力，如果你不能自然而然地想到,请在这方面多下点功夫。

麻省理工公开课 - 化学原理课程节选

All right, so the type of bond energies that we can go and look up in tables are individual atom bonds, H-H, F-F, and the like.

好的，键能的类型,我们能够在表中查到,都是独立的原子键，H-H，F-F以及类似的。

麻省理工公开课 - 固态化学导论课程节选

This is why people right tables and tables of H delta H's. Why you have delta H's from all these reactions, because this is basically the heat and the heat is something we can measure, we can control. We can figure out how much heat is going in and out of something.

这就是为什么人们一再提出ΔH的原因,为什么在所有的反应中你都能看到Δ,因为它就是热量，而且热量,是一种我们可以测量并且控制的东西，我们可以测量出有多少热量,从一些东西里面放出或被吸收。

麻省理工公开课 - 热力学与动力学课程节选