Memorize Common Polyatomic Ions

Having trouble with memorizing common polyatomic ions? Here are a few nomenclature rules that will help you.

Steps

An oxyanion consists of a non-oxygen element and oxygen bonded covalently in some proportion. Since most elements form some type of oxyanion, start by memorizing the most common oxyanions.
The most common oxyanion of a certain element is named by adding the suffix -ate to the name of the non-oxygen element. nitrate - NO₃^-carbonate - CO₃^2-sulfate (sulphate) - SO₄ ^2-phosphate - PO ₄^3-chlorate - ClO₃^-bromate - BrO₃^-iodate - IO₃^-
Some other oxyanions of a certain element can be named according to the following rule. In general, if the number of oxygen atoms in the oxyanion is: 1 greater than the most common oxidation, add the prefix per- the same as the oxyanion, use the name in step 1. 1 less than the most common oxyanion, switch the -ate suffix for -ite. 2 less than the most common oxyanion, switch -ate for -ite and add the prefix hypo-. One example: ClO₄^- - perchlorate ClO₃^- - chlorate ClO₂^- - chlorite ClO^- - hypochlorite Note that the charge of the ion remains the same when you remove an oxygen.
Some other polyatomic ions that are useful to know, which just need to be memorized: Acetate - C₂H₃O₂^- Oxalate - C₂O₄^2- Chromate - CrO₄^2- Dichromate - Cr₂O₇^2-.