Polyatomic Formula
NH4+
Polyatomic Name
Ammonium Ion
C2H3O2- OR CH3COO-
Acetate Ion
BrO3-
Bromate Ion
IO3-
Iodate Ion
ClO4-
Perchlorate Ion
ClO3-
Chlorate Ion
ClO2-
Chlorite Ion
ClO-
Hypochlorite Ion
HCO3-
Bicarbonate Ion
OR
Hydrogen Carbonate Ion
CO32-
Carbonate Ion
NO3-
Nitrate Ion
NO2-
Nitrite Ion
HSO4-
Bisulfate Ion
OR
Hydrogen Sulfate Ion
SO42-
Sulfate Ion
SO32-
Sulfite Ion
PO43-
Phosphate Ion
CrO42-
Chromate Ion
Cr2O72-
Dichromate Ion
OH-
Hydroxide Ion
C2O42-
Oxalate Ion
O22-
Peroxide Ion
MnO4-
Permangat Ion
SCN-
Thiocyanate Ion
CN-
Cyanide Ion
Polyatomic Formula
NH4+
Polyatomic Name
Ammonium Ion
C2H3O2- OR CH3COO-
Acetate Ion
BrO3-
Bromate Ion
IO3-
Iodate Ion
ClO4-
Perchlorate Ion
ClO3-
Chlorate Ion
ClO2-
Chlorite Ion
ClO-
Hypochlorite Ion
HCO3-
Bicarbonate Ion
OR
Hydrogen Carbonate Ion
CO32-
Carbonate Ion
NO3-
Nitrate Ion
NO2-
Nitrite Ion
HSO4-
Bisulfate Ion
OR
Hydrogen Sulfate Ion
SO42-
Sulfate Ion
SO32-
Sulfite Ion
PO43-
Phosphate Ion
CrO42-
Chromate Ion
Cr2O72-
Dichromate Ion
OH-
Hydroxide Ion
C2O42-
Oxalate Ion
O22-
Peroxide Ion
MnO4-
Permangat Ion
SCN-
Thiocyanate Ion
CN-
Cyanide Ion
YOU MUST MEMORIZE ALL 24 POLYATOMIC IONS
By learning the four shaded ions below (and remembering that familys have similar trends), and knowing that one less oxygen
(same charge) turns the name to −ite, and two less oxygens (if possible) turns the name to hypo−xxx−ite and one more oxygen
(if possible) turns the name to per−xxx−ate will make learning all eighteen ions in the chart below as easy as learning just four.
In addition, the prefix bi- adds one hydrogen (reducing the charge by one) turnings the name to bi−xxx−ate or bi−xxx−ite.
Odd Companions or No Companion
hydroxide OH−
cyanide CN−
thiocyanate SCN−
−
acetate C2H3O
carbonate CO32−
bicarbonate HCO3−
2−
sulfate SO4
bicsulfate
HSO4−
chromate CrO42dichromate Cr2O72−
permanganate MnO4
hydroxide OH−
oxalate C2O4−
oxide O2peroxide
O22−
And don’t’ forget
about the only cation
ammonium
NH4+
YOU MUST MEMORIZE ALL 24 POLYATOMIC IONS
By learning the four shaded ions below (and remembering that familys have similar trends), and knowing that one less oxygen
(same charge) turns the name to −ite, and two less oxygens (if possible) turns the name to hypo−xxx−ite and one more oxygen
(if possible) turns the name to per−xxx−ate will make learning all eighteen ions in the chart below as easy as learning just four.
In addition, the prefix bi- adds one hydrogen (reducing the charge by one) turnings the name to bi−xxx−ate or bi−xxx−ite.
Odd Companions or No Companion
hydroxide OH−
cyanide CN−
thiocyanate SCN−
acetate C2H3O−
carbonate CO32−
bicarbonate HCO3−
sulfate SO42−
bicsulfate
HSO4−
2chromate CrO4
dichromate Cr2O72permanganate MnO4−
hydroxide OH−
oxalate C2O4−
oxide O2peroxide
O22−
And don’t’ forget
about the only cation
ammonium
NH4+