The polyatomic ion chart:
Name(acid)  ion:
                   acid:
hypo...ite
hypo...ous
...ite
...ous 

...ate
...ic
per...ate
per...ic
chlor ClO- ClO2-   ClO3- ClO4-
brom BrO- BrO2-   BrO3- BrO4-
iod IO- IO2-   IO3- IO4-
sulf(ur) SO22- SO32-   SO42-
nitr
NO2-   NO3-



     
phosph(or) PO23- PO33-
PO43-
carbon


CO32-
chrom


CrO42-
dichrom


Cr2O72-
mangan



MnO4-

Others:
hydroxide:   OH- hydronium:  H3O+ ammonium:  NH4+

Some special polyatomic ions for which O does not have an oxidation number of -2
 
peroxide  O22- superoxide  O2-