Now, remember, the formation of the ionic bonds was from group one and group two, and over here with group six and seven.

现在请记住，离子键的形成,从第一族和第二族元素，与六七主族的元素相互构成的。

麻省理工公开课 - 固态化学导论课程节选

All of these from the group one and two through the group five and six elements, but what about elements, what about molecules like hydrogen, or nitrogen, or maybe oxygen?

所有的这些都是来自于第一主族和第二组主族,到第五主族和第六组主族的悬殊，那么元素呢，比如氢气，氮气或氧气那样的分子呢？

麻省理工公开课 - 固态化学导论课程节选