We talked about this reaction here where we had chloride ion in the gas phase plus sodium ion in the gas phase.

我们在讨论这一个反应,我们有气相的氯原子,与气相的钠原子接触。

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That is to say I can now reroute that sodium plus chlorine reaction and go a different way, but I still end up with the same change in energy.

也就是说，我可以重新定义一种,钠与氯的反应途径,从另一种途径来实现反应，但是能量的变化过程相同。

麻省理工公开课 - 固态化学导论课程节选

So, for example, if I have a sodium ion over here, and I have a chloride ion over here, where the distance from center to center r I'm denoting as r, this is nucleus to nucleus separation.

所以，比如这有一个钠离子，和一个氯离子，它们中心与中心间的距离,我把它设为，这是原子核和原子和的间距。

麻省理工公开课 - 固态化学导论课程节选