Hi, I was reviewing the polyatomic ions, and on the third row of the periodic table they seemed to follow a pattern going from left to right on the periodic table. For example: Silicate = SiO44-; phosphate = PO43-; sulfate = SO42- For row 3 on the periodic table, it looks like each polyatomic has 4 oxygens, the charge increases by one as one moves to the right along the periodic table, and I think the oxidation numbers of the non-oxygen elements goes +4, +5, +6, respectively. However, chlorate is ClO3-, which seems to break the pattern, since it has only 3 oxygens instead of 4, and the oxidation number on chlorine of +5, instead of +7. Is there any reason chlorate seems to "break" the pattern of the polyatomic ions so far, and any reason why for naming purposes, ClO3- is chlorate, instead of chlorite (like PO33- is phosphite, for example)? Thanks!