The group says fifty-six thousand incidents were reported to the F.A.A.

VOA: special.2009.04.01

There is a striking parallel here in that the group one elements have a tendency to want to give up electrons, F Cl Br whereas the fluorine, chlorine, bromine, have a tendency to attract electrons.

这儿有高度的相似性,每个组都有,失去电子的趋势的，相反的，则是有得电子的趋势。

麻省理工公开课 - 固态化学导论课程节选