1. Why do anions, such as the chloride anion, increase in size when they achieve a full valence electron shell? This does not make sense to me because there is no new shell that is added. 2. How would you name ionic compunds involving polyatomic ions? My book says that (NH4)2CO3 would be ammonium carbonate. This also does not make sense to me because ammonium is not a metal , so there is no reason that it should go first. Thanks for the help!