a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water)
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.
