A catchy phrase or metaphor could help to remember the ions:

nitrite, NO₂^-

SAY NO TO NEGATIVE NITRITE

+1
ammonium, NH₄⁺

hydronium, H₃O⁺

-1
acetate, C₂H₃O₂^-, or CH₃COO ^-
chlorate, ClO₃^-
chlorite, ClO₂^-
cyanide, CN^-
hydrogen carbonate, HCO₃^- (also called bicarbonate)
hydroxide, OH^-
hypochlorite, ClO^-
nitrate, NO₃^-
nitrite, NO₂^-
permanganate, MnO₄^-
perchlorate, ClO₄^-
dihydrogen phosphate, H₂PO₄^-
hydrogen sulfite (bisulfite), HSO₃^-
hydrogen sulfate (bisulfate), HSO₄^-
thiocyanate, SCN ^-

-2
carbonate, CO₃ ^-2
chromate, CrO₄ ^-2
dichromate, Cr₂O₇ ^-2
hydrogen phosphate, HPO₄^-2
silicate, SiO₃^-2
oxalate, C₂O₄ ^-2
sulfate, SO₄ ^-2
sulfite, SO₃ ^-2

-3
phosphate, PO₄ ^-3
phosphite, PO₃ ^-3