Last updated on January 12th, 2024 at 01:53 pm

Memorizing the Names of Polyatomic Ions - High School/Honors/AP® Chemistry Resources | Viziscience
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Examples of polyatomic ions

Generally, polyatomic ions have suffixes that end in “ite” or “ate” if they contain oxygen atoms.  

chloridehypochloritechloritechlorateperchlorate
Note: Chloride shown above is not a polyatomic ion, it's a monoatomic ion consisting of only one atom.

Examples of other polyatomic ions:

list of polyatomic ions

Oxyanions

Oxyanions are ions that contain oxygen atoms.

  • For example, chlorine can combine with oxygen in 4 ways to form 4 different oxyanions.
  • You will notice that the charge in a family of oxyanions remains the same.
  • This group of oxyanions has a charge of 1-.
prefix HYPO  PER
suffix iteiteateate
anion namechloridehypochloritechloritechlorateperchlorate
#oxygen atoms01334
formulaCl⁻
ClO⁻
ClO₂⁻
ClO₃⁻
ClO₄⁻
structure

Look at the names of each polyatomic ions above.

  • Hypochlorite – has the suffix “Hypo”, has the least number of oxygen atoms.
  • Perchlorate – has the suffix “Per”, has the most number of oxygen atoms.

Periodic table

The small group of non-metals in the periodic table below commonly form bonds with oxygen, and they are also able to combine with oxygen in a number of ways to form different oxyanions.

Remember, that in a family of oxyanions, the charge remains the same. So, for example, the boron family of oxyanions will have a charge of 3-. Carbon will have 2-, and nitrogen will have 2-. You can find these charges in the periodic table below.

As far as the naming goes, the group of elements (B,C,N,O,F, Br and I) will have naming pattern shown above for the chlorine family.

The nitrogen family

prefix HYPO  PER
suffix iteiteateate
anion namenitridehyponitritenitritenitratepernitrate
#oxygen atoms01234
formulaN³⁻
NO⁻
NO₂⁻
NO₃⁻
NO₄⁻

The phosphorus family

The four elements inside the group (P,S,As,Se), their names follow the same pattern but they have an extra oxygen atom.

prefix HYPO  PER
suffix iteiteateate
anion namephosphidehypophosphitephosphitephosphateperphosphate
#oxygen atoms02345
formulaP³⁻
PO₂³⁻
PO₃³⁻
PO₄³⁻
PO₅³⁻

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