2012/06/26

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Notice that when "thio" appears in the name, it often means that one of the oxygens has been replaced by a sulfur.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.


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