Polyatomic ions

You should know the following polyatomic ions:
Nitrate (NO₃^-1), sulfate (SO₄^-2), carbonate (CO₃^-2), phosphate (PO₄^-3), chlorate (ClO₃^-1), bromate (BrO₃^-1), iodate (IO₃^-1), hydroxide (OH^-1), cyanide (CN^-1), cyanate (OCN^-1), thiocyanate (SCN^-1), thiosulfate (S₂O₃^-2), permanganate (MnO₄^-1), chromate (CrO₄^-2), dichromate (Cr₂O₇^-2), ammonium (NH₄⁺¹)
Notice that when "thio" appears in the name, it often means that one of the oxygens has been replaced by a sulfur.
In a couple weeks we'll be looking at acids and bases, and a number of these polyatomic ions can be protonated to form additional polyatomic ions that you should also know such as:
bicarbonate/hydrogen carbonate (HCO₃^-1), bisulfate/hydrogensulfate (HSO₄^-2), hydrogen phosphate (HPO₄^-2), dihydrogen phosphate (H₂PO₄^-1)
Oxoanions are systematically named using suffixes and prefixes, so you should be able to determine formulas/names for the full family of an oxoanion. Let's look at the chlorine family as an example... chlorATE is ClO₃^-1. If we add an oxygen to chlorate but keep the same charge, we get PERchlorATE, ClO₄^-1. If we remove an oxygen from chlorate but keep the same charge, we get chlorITE, ClO₂^-1. If we remove another oxygen but keep the same charge, we get HYPOchlorITE, ClO^-1. If you know all the "-ate" versions of the oxoanions, you should be able to get the rest of them.