Polyatomic anions are made up more than one atom. Among the commonly encountered polyatomic anions are

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hydroxide OH^-

found in bases such as
lithium hydroxide LiOH
potassium hydroxide KOH
sodium hydroxide NaOH
calcium hydroxide Ca(OH)₂
ammonium hydroxide NH₄OH

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nitrate NO₃^-

found in
potassium nitrate KNO₃
sodium nitrate NaNO₃
ammonium nitrate NH₄NO₃
silver nitrate AgNO₃
calcium nitrate Ca(NO₃)₂
copper (II) nitrate Cu(NO₃)₂
lead (II) nitrate Pb(NO₃)₂

*all nitrate salts are soluble in water

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sulphate SO₄^2-

found in
potassium sulphate K₂SO₄
sodium sulphate Na₂SO₄
ammonium sulphate (NH₄)₂SO₄
calcium sulphate CaSO₄
copper (II) sulphate CuSO₄
lead (II) sulphate PbSO₄
barium sulphate BaSO₄

PbSO₄  BaSO₄ and CaSO₄ are insoluble in water

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carbonate CO₃^2-

found in
potassium carbonate K₂CO₃
sodium carbonate Na₂CO₃
calcium carbonate CaCO₃
copper (II) carbonate CuCO₃
lead (II) carbonate PbCO₃

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Anion poliatomik terdiri daripada lebih satu atom. Di antara anion poliatomik adalah hidroksida OH^-, nitrat NO₃^-, sulfat SO₄^2-  dan karbonat CO₃^2- .
hidroksida OH^-

contoh-contoh
litium hidroksida LiOH
kalium hidroksida KOH
natrium hidroksida NaOH
kalsium hidroksida Ca(OH)₂
amonium hidroksida NH₄OH

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nitrat NO₃^-

contoh-contoh
kalium nitrat KNO₃
natrium nitrat NaNO₃
amonium nitrat NH₄NO₃
argentum nitrat AgNO₃
kalsium nitrat Ca(NO₃)₂
kuprum (II) nitrat Cu(NO₃)₂
plumbum (II) nitrat Pb(NO₃)₂

*semua garam nitrat boleh larut dalam air

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sulfat SO₄^2-

contoh-contoh
kalium sulfat K₂SO₄
natrium sulfat Na₂SO₄
amonium sulfat (NH₄)₂SO₄
kalsium sulfat CaSO₄
kuprum (II) sulfat CuSO₄
plumbum (II) sulfat PbSO₄
barium sulfat BaSO₄

PbSO₄  BaSO₄ dan CaSO₄ tidak larut dalam air

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karbonat CO₃^2-

contoh-contoh
kalium karbonat K₂CO₃
natrium karbonat Na₂CO₃
kalsium karbonat CaCO₃
kuprum (II) karbonat CuCO₃
plumbum (II) karbonat PbCO₃

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