Polyatomic ion: Difference between revisions

Latest revision as of 16:09, 5 September 2025

Template:Short description Template:More citations needed

An electrostatic potential map of the nitrate ion (Template:Chem2). Areas coloured translucent red, around the outside of the red oxygen atoms themselves, signify the regions of most negative electrostatic potential.

A polyatomic ion (also known as a molecular ion) is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that usually has a net charge that is not zero,^[1] or in special case of zwitterion wear spatially separated charges where the net charge may be variable depending on acidity conditions. The term molecule may or may not be used to refer to a polyatomic ion, depending on the definition used. The prefix poly- carries the meaning "many" in Greek, but even ions of two atoms are commonly described as polyatomic.^[2] There may be more than one atom in the structure that has non-zero charge, therefore the net charge of the structure may have a cationic (positive) or anionic nature depending on those atomic details.

In older literature, a polyatomic ion may instead be referred to as a radical (or less commonly, as a radical group).Script error: No such module "Unsubst". In contemporary usage, the term radical refers to various free radicals, which are species that have an unpaired electron and need not be charged.^[3]

A simple example of a polyatomic ion is the hydroxide ion, which consists of one oxygen atom and one hydrogen atom, jointly carrying a net charge of −1; its chemical formula is Template:Chem2. In contrast, an ammonium ion consists of one nitrogen atom and four hydrogen atoms, with a charge of +1; its chemical formula is Template:Chem2.

Polyatomic ions often are useful in the context of acid–base chemistry and in the formation of salts.

Often, a polyatomic ion can be considered as the conjugate acid or base of a neutral molecule. For example, the conjugate base of sulfuric acid (H₂SO₄) is the polyatomic hydrogen sulfate anion (Template:Chem2). The removal of another hydrogen ion produces the sulfate anion (Template:Chem2).

Nomenclature of polyatomic anions

There are several patterns that can be used for learning the nomenclature of polyatomic anions. First, when the prefix bi is added to a name, a hydrogen is added to the ion's formula and its charge is increased by 1, the latter being a consequence of the hydrogen ion's +1 charge. An alternative to the bi- prefix is to use the word hydrogen in its place: the anion derived from Template:Chem2. For example, let us consider the carbonate(Template:Chem2) ion:

Template:Chem2 + Template:Chem2 → Template:Chem2,

which is called either bicarbonate or hydrogen carbonate. The process that forms these ions is called protonation.

Naming oxyanions

Most of the common polyatomic anions are oxyanions, conjugate bases of oxyacids (acids derived from the oxides of non-metallic elements). For example, the sulfate anion, Template:Chem2, is derived from Template:Chem2, which can be regarded as Template:Chem2 + Template:Chem2.

The second rule is based on the oxidation state of the central atom in the ion, which in practice is often (but not always) directly related to the number of oxygen atoms in the ion, following the pattern shown below. The following table shows the chlorine oxyanion family:

Oxidation state	−1	+1	+3	+5	+7
Anion name	chloride	hypochlorite	chlorite	chlorate	perchlorate
Formula	Template:Chem2	Template:Chem2	Template:Chem2	Template:Chem2	Template:Chem2
Structure	The chloride ion	The hypochlorite ion	The chlorite ion	The chlorate ion	The perchlorate ion

As the number of oxygen atoms bound to chlorine increases, the chlorine's oxidation number becomes more positive. This gives rise to the following common pattern: first, the -ate ion is considered to be the base name; adding a per- prefix adds an oxygen (or otherwise increases the oxidation state), while changing the -ate suffix to -ite will reduce the oxygens by one, and keeping the suffix -ite and adding the prefix hypo- reduces the number of oxygens by one more, all without changing the charge. The naming pattern follows within many different oxyanion series based on a standard root for that particular series. The -ite has one less oxygen than the -ate, but different -ate anions might have different numbers of oxygen atoms.

Generally, the change in prefix corresponds to a change in oxidation state. The main exception is the per- prefix, as only halogens and some transition metals can be oxidized to the +7 or greater oxidation states that would normally use per-. For other elements, it is used as shorthand for peroxy-, which has the same oxidation state as the prior -ate anion, but contains a peroxide group instead of a single oxygen. There are also cases where the oxidation state increases but the number of oxygen atoms does not, such as the oxidation of manganate (Template:Chem2) to permanganate (Template:Chem2).

Some oxyanions form dimers, usually by losing an equivalent of oxide. These anions are given the prefix di- or pyro- (as many can be prepared by heating).^[4] These anions contain Template:Chem2 bonds, and are structurally related to acid anhydrides of the conjugate acid. The pyro- prefix is only used for these kinds of dimers; others, such as hyponitrite, contain different bond structures despite having a formula that suggests it is "made" of two nitroxide units.

The following table shows the patterns of ion naming for some common ions and their derivatives. Exceptions to the rules are highlighted in yellow, while anions too unstable to exist are marked out with a red "none".

Element	Type of anion	Reduced anion		hypo-		-ite		-ate		per- or peroxy-
Chlorine	All	Chloride	Template:Chem2	Hypochlorite	Template:Chem2	Chlorite	Template:Chem2	Chlorate	Template:Chem2	Perchlorate	Template:Chem2
Nitrogen	Simple anion	Nitride	Template:Chem2	Template:CellCategory	Template:CellCategory	Nitrite	Template:Chem2	Nitrate	Template:Chem2	Peroxynitrate	Template:Chem2
Nitrogen	<templatestyles src="Template:Tooltip/styles.css" />DimerScript error: No such module "Check for unknown parameters".	Template:CellCategory	Template:CellCategory	Template:CellCategory	Template:CellCategory	None		None		None
Sulfur	Simple anion	Sulfide	Template:Chem2	Template:CellCategory	Template:CellCategory	Sulfite	Template:Chem2	Sulfate	Template:Chem2	Persulfate or peroxysulfate	Template:Chem2
	Protonated	Bisulfide	Template:Chem2	Hydrogen sulfoxylate	Template:Chem2	Bisulfite or hydrogen sulfite	Template:Chem2	Bisulfate or hydrogen sulfate	Template:Chem2	Hydrogen persulfate	Template:Chem2
	Dimer	Disulfide	Template:Chem2	<templatestyles src="Template:Tooltip/styles.css" />NoneScript error: No such module "Check for unknown parameters".		Pyrosulfite or disulfite	Template:Chem2	Pyrosulfate or disulfate	Template:Chem2	Peroxydisulfate	Template:Chem2
Phosphorus	Simple anion	Phosphide	Template:Chem2	None		None		Phosphate or orthophosphate	Template:Chem2	Peroxymonophosphate	Template:Chem2
	Protonated once	None		None		Template:CellCategory	Template:CellCategory	Hydrogen phosphate	Template:Chem2	Hydrogen peroxymonophosphate	Template:Chem2
	Protonated twice	Template:CellCategory	Template:CellCategory	Template:CellCategory	Template:CellCategory	Hydrogen phosphite	Template:Chem2	Dihydrogen phosphate	Template:Chem2	Dihydrogen peroxymonophosphate	Template:Chem2
	Dimer	No dimer; many other polyphosphides	Template:Chem2, Template:Chem2, Template:Chem2, etc.	None		Diphosphite or pyrophosphite	Template:Chem2	Diphosphate or pyrophosphate	Template:Chem2	Peroxydiphosphate	Template:Chem2

Other examples of common polyatomic ions

The following tables give additional examples of commonly encountered polyatomic ions in various categories. Only a few representatives are given, as the number of polyatomic ions encountered in practice is very large.

Anions
Inorganic carbon anions		Alkoxides		Carboxylates		Transition metal oxyanions		Other notable anions
Carbonate	Template:Chem2	Methoxide (methanolate)	Template:Chem2	Formate (methanoate)	Template:Chem2	Manganate	Template:Chem2	Hydroxide	Template:Chem2
Bicarbonate or hydrogen carbonate	Template:Chem2	Ethoxide (ethanolate)	Template:Chem2	Acetate (ethanoate)	Template:Chem2	Permanganate	Template:Chem2	Peroxide	Template:Chem2
Acetylide	Template:Chem2	Phenolate	Template:Chem2	Benzoate	Template:Chem2 or Template:Chem2	Chromate	Template:Chem2	Superoxide	Template:Chem2
Cyanide	Template:Chem2	tert-Butoxide	Template:Chem2	Oxalate	Template:Chem2	Dichromate	Template:Chem2	Azanide	Template:Chem2
Cyanate	Template:Chem2			Citrate	Template:Chem2	Orthotungstate	Template:Chem2	Orthosilicate	Template:Chem2
Thiocyanate	Template:Chem2							Borohydride	Template:Chem2

Cations
Onium ions		Carbenium ions		Others
Guanidinium	Template:Chem2	Tropylium	Template:Chem2	Mercury(I)	Template:Chem2
Ammonium	Template:Chem2	Triphenylcarbenium	Template:Chem2	Dihydrogen	Template:Chem2
Phosphonium	Template:Chem2	Cyclopropenium	Template:Chem2
Hydronium	Template:Chem2	Trifluoromethyl	Template:Chem2
Fluoronium	Template:Chem2
Pyrylium	Template:Chem2
Sulfonium	Template:Chem2

Zwitterion and polycharged polyatomic ions

Many polyatomic molecules can carry spatially separated charges, forming polycharged polyatomic ions. An important case of these compounds are zwitterions, which are neutral compounds but have opposing formal charges within the same molecule.^[5] A typical example are amino acids, which carry both charged amino and carboxyl groups. These charges can influence the chemical^[6] and physical properties of substances.^[7]

Many zwitterions exhibit tautomerism with a "parent" molecule without formal charges. For example, glycine reversibly converts between the parent molecule and a zwitterionic form by transfer of a labile hydrogen atom between the protonated amino group and carboxylate group.^[8] By contrast, trimethylglycine has three non-labile methyl groups, making quaternary ammonium, so it does not interconvert with the non-zwitterionic isomer (a dimethylglycine ester). These non-tautomeric zwitterions are called betaines.^[9]

Applications

Polyatomic ion structure may influence thin film growth.^[10] Analyses of polyatomic ion composition is key point in mass-spectrometry.^[11]^[12]^[13]

References

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[6] Script error: No such module "Citation/CS1".

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[9] Template:GoldBookRef

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[11] Script error: No such module "Citation/CS1".

[12] Script error: No such module "Citation/CS1".

[13] Script error: No such module "Citation/CS1".

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[12]

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Polyatomic ion: Difference between revisions

Latest revision as of 16:09, 5 September 2025

Contents

Nomenclature of polyatomic anions

Naming oxyanions

Other examples of common polyatomic ions

Zwitterion and polycharged polyatomic ions

Applications

See also

References

External links

Navigation menu

@@ Line 3: / Line 3: @@
 [[File:Nitrate-ion-elpot.png|thumb|right|200px|An [[electric potential|electrostatic potential]] map of the [[nitrate]] ion ({{chem2|auto=yes|NO3-}}). Areas coloured translucent red, around the outside of the red oxygen atoms themselves, signify the regions of most negative electrostatic potential.]]
-A '''polyatomic ion''' (also known as a '''molecular ion''') is a [[covalent bond]]ed set of two or more [[atom]]s, or of a [[complex (chemistry)|metal complex]], that can be considered to behave as a single unit and that usually has a net [[electrical charge|charge]] that is not zero,<ref name="PetrucciA50">{{cite book |last1=Petrucci |first1=Ralph H. |last2=Herring |first2=F. Geoffrey |last3=Madura |first3=Jeffry D. |last4=Bissonnette |first4=Carey |title=General chemistry: principles and modern applications |date=2017 |publisher=Pearson |location=Toronto |isbn=978-0-13-293128-1 |page=A50 |edition=Eleventh}}</ref> or in special case of [[zwitterion]] wear spatially separated charges where the net charge may be variable depending on [[Acidity function|acidity]] conditions.  The term [[molecule]] may or may not be used to refer to a polyatomic ion, depending on the definition used. The prefix ''poly-'' carries  the meaning "many" in Greek, but even ions of two atoms are commonly described as polyatomic.<ref>{{Cite web |title=Ionic Compounds Containing Polyatomic Ions |url=https://www.chem.purdue.edu/gchelp/nomenclature/poly_atom.htm |access-date=2022-04-16 |website=www.chem.purdue.edu}}</ref>
+A '''polyatomic ion''' (also known as a '''molecular ion''') is a [[covalent bond]]ed set of two or more [[atom]]s, or of a [[complex (chemistry)|metal complex]], that can be considered to behave as a single unit and that usually has a net [[electrical charge|charge]] that is not zero,<ref name="PetrucciA50">{{cite book |last1=Petrucci |first1=Ralph H. |last2=Herring |first2=F. Geoffrey |last3=Madura |first3=Jeffry D. |last4=Bissonnette |first4=Carey |title=General chemistry: principles and modern applications |date=2017 |publisher=Pearson |location=Toronto |isbn=978-0-13-293128-1 |page=A50 |edition=Eleventh}}</ref> or in special case of [[zwitterion]] wear spatially separated charges where the net charge may be variable depending on [[Acidity function|acidity]] conditions.  The term [[molecule]] may or may not be used to refer to a polyatomic ion, depending on the definition used. The prefix ''poly-'' carries  the meaning "many" in Greek, but even ions of two atoms are commonly described as polyatomic.<ref>{{Cite web |title=Ionic Compounds Containing Polyatomic Ions |url=https://www.chem.purdue.edu/gchelp/nomenclature/poly_atom.htm |access-date=2022-04-16 |website=www.chem.purdue.edu}}</ref> There may be more than one atom in the structure that has non-zero charge, therefore the net charge of the structure may have a [[cation]]ic (positive) or [[anion]]ic nature depending on those atomic details.
 In older literature, a polyatomic ion may instead be referred to as a ''[[Radical (chemistry)|radical]]'' (or less commonly, as a ''radical group'').{{Citation needed|date=June 2022}} In contemporary usage, the term ''radical'' refers to various [[Radical (chemistry)|free radical]]s, which are [[species (chemistry)|species]] that have an [[unpaired electron]] and need not be charged.<ref>{{cite web |title=IUPAC - radical (free radical) (R05066) |url=https://goldbook.iupac.org/terms/view/R05066 |website=goldbook.iupac.org |access-date=25 January 2023}}</ref>
@@ Line 20: / Line 20: @@
 which is called either bicarbonate or hydrogen carbonate. The process that forms these ions is called [[protonation]].
+=== Naming oxyanions ===
 Most of the common polyatomic anions are [[oxyanion]]s, conjugate bases of [[oxyacid]]s (acids derived from the [[oxide]]s of [[Nonmetal (chemistry)|non-metallic elements]]). For example, the [[sulfate]] anion, {{chem2|auto=yes|SO4(2-)}}, is derived from {{chem2|link=sulfuric acid|H2SO4}}, which can be regarded as {{chem2|link=sulfur trioxide|SO3}} + {{chem2|link=water|H2O}}.
@@ Line 54: / Line 55: @@
 |}
-As the number of oxygen atoms bound to chlorine increases, the chlorine's oxidation number becomes more positive. This gives rise to the following common pattern: first, the ''-ate'' ion is considered to be the base name; adding a ''per-'' prefix adds an oxygen, while changing the ''-ate'' suffix to ''-ite'' will reduce the oxygens by one, and keeping the suffix ''-ite'' and adding the prefix ''hypo-'' reduces the number of oxygens by one more, all without changing the charge. The naming pattern follows within many different oxyanion series based on a standard root for that particular series. The ''-ite'' has one less oxygen than the ''-ate'', but different ''-ate'' anions might have different numbers of oxygen atoms.
+As the number of oxygen atoms bound to chlorine increases, the chlorine's oxidation number becomes more positive. This gives rise to the following common pattern: first, the ''-ate'' ion is considered to be the base name; adding a ''per-'' prefix adds an oxygen (or otherwise increases the [[oxidation state]]), while changing the ''-ate'' suffix to ''-ite'' will reduce the oxygens by one, and keeping the suffix ''-ite'' and adding the prefix ''hypo-'' reduces the number of oxygens by one more, all without changing the charge. The naming pattern follows within many different oxyanion series based on a standard root for that particular series. The ''-ite'' has one less oxygen than the ''-ate'', but different ''-ate'' anions might have different numbers of oxygen atoms.
-These rules do not work with all polyatomic anions, but they do apply to several of the more common ones. The following table shows how these prefixes are used for some of these common anion groups.
+Generally, the change in prefix corresponds to a change in [[oxidation state]]. The main exception is the ''per-'' prefix, as only [[halogen]]s and some [[transition metal]]s can be oxidized to the +7 or greater oxidation states that would normally use ''per-''. For other elements, it is used as shorthand for ''peroxy-'', which has the same oxidation state as the prior ''-ate'' anion, but contains a [[peroxide]] group instead of a single oxygen. There are also cases where the oxidation state increases but the number of oxygen atoms does not, such as the oxidation of [[manganate]] ({{chem2|MnO4(2-)}}) to [[permanganate]] ({{chem2|MnO4-}}).
-{| class="wikitable"
+Some oxyanions form [[dimer (chemistry)|dimer]]s, usually by losing an equivalent of [[oxide]]. These anions are given the prefix ''di-'' or ''pyro-'' (as many can be prepared by heating).<ref>{{GoldBookRef|title=pyro|file=P04959}}</ref> These anions contain {{chem2|X\sO\sX}} bonds, and are structurally related to [[acid anhydride]]s of the [[conjugate acid]]. The ''pyro-'' prefix is only used for these kinds of dimers; others, such as [[hyponitrite]], contain different bond structures despite having a formula that suggests it is "made" of two [[nitroxide]] units.
-|-
-| [[bromide]]
-| [[hypobromite]]
-| [[bromite]]
-| [[bromate]]
-| [[perbromate]]
-|-
-| {{chem2|Br-}}
-| {{chem2|BrO-}}
-| {{chem2|BrO2-}}
-| {{chem2|BrO3-}}
-| {{chem2|BrO4-}}
-|-
-| [[iodide]]
-| [[hypoiodite]]
-| [[iodite]]
-| [[iodate]]
-| [[periodate]]
-|-
-| {{chem2|I-}}
-| {{chem2|IO-}}
-| {{chem2|IO2-}}
-| {{chem2|IO3-}}
-| {{chem2|IO4-}} or {{chem2|IO6(5-)}}
-|-
-| [[sulfide]]
-| [[hyposulfite]]
-| [[sulfite]]
-| [[sulfate]]
-| [[persulfate]]
-|-
-| {{chem2|S(2-)}}
-| {{chem2|S2O2(2-)}}
-| {{chem2|SO3(2-)}}
-| {{chem2|SO4(2-)}}
-| {{chem2|SO5(2-)}} or {{chem2|S2O8(2-)}}
-|-
-| [[selenide]]
-| [[hyposelenite]]
-| [[Selenite (ion)|selenite]]
-| [[selenate]]
-|
-|-
-| {{chem2|Se2-}}
-| {{chem2|Se2O2(2-)}}
-| {{chem2|SeO3(2-)}}
-| {{chem2|SeO4(2-)}}
-|
-|-
-| [[Telluride (chemistry)|telluride]]
-| [[hypotellurite]]
-| [[tellurite (ion)|tellurite]]
-| [[tellurate]]
-|
-|-
-| {{chem2|Te2-}}
-| {{chem2|TeO2(2-)}}
-| {{chem2|TeO3(2-)}}
-| {{chem2|TeO4(2-)}}
-|
-|-
-| [[nitride]]
-| [[hyponitrite]]
-| [[nitrite]]
-| [[nitrate]]
-| [[peroxynitrate|pernitrate]]
-|-
-| {{chem2|N3-}}
-| {{chem2|N2O2(2-)}}
-| {{chem2|NO2-}}
-| {{chem2|NO3-}}
-| {{chem2|NO4-}}
-|-
-| [[phosphide]]
-| [[hypophosphite]]
-| [[phosphite]]
-| [[phosphate]]
-| [[perphosphate]]
-|-
-| {{chem2|P3-}}
-| {{chem2|H2PO2-}}
-| {{chem|PO|3|3-}}
-| {{chem|PO|4|3-}}
-| {{chem|PO|5|3-}}
-|-
-| [[arsenide]]
-| [[hypoarsenite]]
-| [[arsenite]]
-| [[arsenate]]
-|
-|-
-| {{chem|As|3-}}
-| {{chem|AsO|2|3-}}
-| {{chem|AsO|3|3-}}
-| {{chem|AsO|4|3-}}
-|
-|-
-|}
-Some oxo-anions can [[dimer (chemistry)|dimer]]ize with loss of an oxygen atom. The prefix ''pyro'' is used, as the reaction that forms these types of chemicals often involves heating to form these types of structures.<ref>{{GoldBookRef|file=P04959|title=pyro}}</ref> The prefix ''pyro'' is also denoted by the prefix ''di-'' . For example, dichromate ion is a dimer.
+The following table shows the patterns of ion naming for some common ions and their derivatives. Exceptions to the rules are highlighted in yellow, while anions too unstable to exist are marked out with a red "none".
-{|class=wikitable
+{|class="wikitable"
-| [[sulfite]]
+! Element
-| [[pyrosulfite]]
+! Type of anion
-|-
+!colspan=2 | Reduced anion
-| {{chem|S|O|3|2-}}
+!colspan=2 | ''hypo-''
-| {{chem|S|2|O|5|2-}}
+!colspan=2 | ''-ite''
-|-
+!colspan=2 | ''-ate''
-| [[sulfate]]
+!colspan=2 | ''per-'' or ''peroxy-''
-| [[pyrosulfate]]
-|-
-| {{chem|S|O|4|2-}}
-| {{chem|S|2|O|7|2-}}
-|-
-| [[phosphite anion|phosphite]]
-| [[pyrophosphite]]
-|-
-| {{chem|P|O|3|3-}}
-| {{chem|P|2|O|5|4-}}
 |-
-| [[phosphate]]
+! [[Chlorine]]
-| [[pyrophosphate]]
+! All
+| [[Chloride]] || {{chem2|Cl-}}
+| [[Hypochlorite]] || {{chem2|ClO-}}
+| [[Chlorite]] || {{chem2|ClO2-}}
+| [[Chlorate]] || {{chem2|ClO3-}}
+| [[Perchlorate]] || {{chem2|ClO4-}}
 |-
-| {{chem|P|O|4|3-}}
+! rowspan=2 | [[Nitrogen]]
-| {{chem|P|2|O|7|4-}}
+! Simple anion
+| [[Nitride]] || {{chem2|N(3-)}}
+| {{CellCategory|1|[[Nitroxyl|Nitroxide]]}} || {{CellCategory|1|{{chem2|NO-}}}}
+| [[Nitrite]] || {{chem2|NO2-}}
+| [[Nitrate]] || {{chem2|NO3-}}
+| [[Peroxynitrate]] || {{chem2|NO4-}}
 |-
-| [[arsenate]]
+! {{Tooltip|Dimer|Nitrogen anions do not form anionic N-O-N dimers. These anions contain N-N bonds.}}
-| [[pyroarsenate]]
+| {{CellCategory|1|No dimer; [[azide]] trimer}} || {{CellCategory|1|{{chem2|N3-}}}}
+| {{CellCategory|1|[[Hyponitrite]]}} || {{CellCategory|1|{{chem2|N2O2(2-)}}}}
+| colspan=2 {{no2|None}}
+| colspan=2 {{no2|None}}
+| colspan=2 {{no2|None}}
 |-
-| {{chem|As|O|4|3-}}
+! rowspan=3 | [[Sulfur]]
-| {{chem|As|2|O|7|4-}}
+! Simple anion
+| [[Sulfide]] || {{chem2|S(2-)}}
+| {{CellCategory|1|[[Sulfoxylic acid|Sulfoxylate]]}} || {{CellCategory|1|{{chem2|SO2(2-)}}}}
+| [[Sulfite]] || {{chem2|SO3(2-)}}
+| [[Sulfate]] || {{chem2|SO4(2-)}}
+| [[Persulfate]] or peroxysulfate || {{chem2|SO5(2-)}}
 |-
-| [[Chromate and dichromate|chromate]]
+! Protonated
-| [[dichromate]]
+| [[Bisulfide]] || {{chem2|HS-}}
+| [[Sulfoxylic acid|Hydrogen sulfoxylate]] || {{chem2|HSO2-}}
+| [[Bisulfite]] or hydrogen sulfite || {{chem2|HSO3-}}
+| [[Bisulfate]] or hydrogen sulfate || {{chem2|HSO4-}}
+| Hydrogen persulfate || {{chem2|HSO5-}}
 |-
-| {{chem|CrO|4|2-}}
+! Dimer
-| {{chem|Cr|2|O|7|2-}}
+| [[Disulfide]] || {{chem2|S2(2-)}}
+| colspan=2 {{no2|{{tooltip|None|The S2O3(2-) anion is the non-dimeric thiosulfate.}}}}
+| Pyrosulfite or [[disulfite]] || {{chem2|S2O5(2-)}}
+| [[Pyrosulfate]] or disulfate || {{chem2|S2O7(2-)}}
+| [[Peroxydisulfate]] || {{chem2|S2O8(2-)}}
 |-
-| [[carbonate]]
+! rowspan=4 | [[Phosphorus]]
-| [[dicarbonate]]
+! Simple anion
+| [[Phosphide]] || {{chem2|P(3-)}}
+| colspan=2 {{no2|None}}
+| colspan=2 {{no2|None}}
+| [[Phosphate]] or orthophosphate || {{chem2|PO4(3-)}}
+| [[Peroxymonophosphoric acid|Peroxymonophosphate]] || {{chem2|PO5(3-)}}
 |-
-| {{chem|CO|3|2-}}
+! Protonated once
-| {{chem|C|2|O|5|2-}}
+| colspan=2 {{no2|None}}
+<!--| {{CellCategory|1|[[Phosphinidene]]}} || {{CellCategory|1|{{chem2|HP(2-)}}}} -->
+| colspan=2 {{no2|None}}
+| {{CellCategory|1|[[Phosphite (ion)|Phosphite]]}} || {{CellCategory|1|{{chem2|HPO3(2-)}}}}
+| Hydrogen phosphate || {{chem2|HPO4(2-)}}
+| Hydrogen peroxymonophosphate || {{chem2|HPO5(2-)}}
 |-
-|selenite
+! Protonated twice
-|pyroselenite
+| {{CellCategory|1|[[Phosphanide]]}} || {{CellCategory|1|{{chem2|H2P-}}}}
+| {{CellCategory|1|[[Phosphinate]] or hypophosphite}} || {{CellCategory|1|{{chem2|H2PO2-}}}}
+| Hydrogen phosphite || {{chem2|H2PO3-}}
+| Dihydrogen phosphate || {{chem2|H2PO4-}}
+| Dihydrogen peroxymonophosphate || {{chem2|H2PO5(-)}}
 |-
-|{{chem|SeO|3|2-}}
+! Dimer
-|{{chem|Se|2|O|5|2-}}
+| No dimer; many other [[polyphosphide]]s || {{chem2|P4(2-)}}, {{chem2|P7(3-)}}, {{chem2|P11(3-)}}, etc.
+| colspan=2 {{no2|None}}
+| Diphosphite or [[pyrophosphite]] || {{chem2|H2P2O5(2-)}}
+| Diphosphate or [[pyrophosphate]] || {{chem2|P2O7(4-)}}
+| [[Peroxydiphosphoric acid|Peroxydiphosphate]] || {{chem2|P4O8(4-)}}
 |}
 ==Other examples of common polyatomic ions==
-The following tables give additional examples of commonly encountered polyatomic ions. Only a few representatives are given, as the number of polyatomic ions encountered in practice is very large.
+The following tables give additional examples of commonly encountered polyatomic ions in various categories. Only a few representatives are given, as the number of polyatomic ions encountered in practice is very large.
 {|class="wikitable"
 |+ [[Anion]]s
+! colspan=2 | Inorganic [[carbon]] anions
+! colspan=2 | [[Alkoxide]]s
+! colspan=2 | [[Carboxylate]]s
+! colspan=2 | [[Transition metal]] oxyanions
+! colspan=2 | Other notable anions
 |-
-| [[Tetrahydroxyborate]]
+| [[Carbonate]] || {{chem2|CO3(2-)}}
-| {{chem2|B(OH)4-}}
+| [[Methoxide]] (methanolate) || {{chem2|CH3O-}}
-|-
+| [[Formate]] (methanoate) || {{chem2|HCOO-}}
-| [[Acetylide]]
+| [[Manganate]] || {{chem2|MnO4(2-)}}
-| {{chem2|C2(2-)}}
+| [[Hydroxide]] || {{chem2|OH-}}
-|-
-| [[Ethoxide]] or ethanolate
-| {{chem2|C2H5O-}}
-|-
-| [[Acetate]] or ethanoate
-| {{chem2|CH3COO-}} or {{chem2|C2H3O2-}}
-|-
-| [[Benzoate]]
-| {{chem2|C6H5COO-}} or {{chem2|C7H5O2-}}
-|-
-| [[Citrate]]
-| {{chem2|C6H5O7(3-)}}
-|-
-| [[Formate]]
-| {{chem2|HCOO-}}
-|-
-| [[Carbonate]]
-| {{chem2|CO3(2-)}}
-|-
-| [[Oxalate]]
-| {{chem2|C2O4(2-)}}
-|-
-| [[Cyanide]]
-| {{chem2|CN-}}
-|-
-| [[Chromate and dichromate|Chromate]]
-| {{chem2|CrO4(2-)}}
-|-
-| [[Chromate and dichromate|Dichromate]]
-| {{chem2|Cr2O7(2-)}}
-|-
-| [[Bicarbonate]] or hydrogencarbonate
-| {{chem2|HCO3(-)}}
-|-
-| [[Phosphate#Chemical properties|Hydrogen phosphate]]
-| {{chem2|HPO4(2-)}}
-|-
-| [[Phosphate#Chemical properties|Dihydrogen phosphate]]
-| {{chem2|H2PO4(-)}}
-|-
-| [[Hydrogen sulfate]] or bisulfate
-| {{chem2|HSO4(-)}}
-|-
-| [[Manganate]]
-| {{chem2|MnO4(2-)}}
-|-
-| [[Permanganate]]
-| {{chem2|MnO4(-)}}
-|-
-| [[Zincate]]
-| {{chem2|ZnO2(2-)}}
-|-
-| [[Aluminate]]
-| {{chem2|AlO2-}}
-|-
-| [[Tungstate]]
-| {{chem2|WO4(2-)}}
-|-
-| [[Azanide]] or amide
-| {{chem2|NH2(-)}}
 |-
-| [[Peroxide]]
+| [[Bicarbonate]] or hydrogen carbonate || {{chem2|HCO3-}}
-| {{chem2|O2(2-)}}
+| [[Ethoxide]] (ethanolate) || {{chem2|CH3CH2O- or C2H5O-}}
+| [[Acetate]] (ethanoate) || {{chem2|CH3COO- or C2H3O-}}
+| [[Permanganate]] || {{chem2|MnO4-}}
+| [[Peroxide]] || {{chem2|O2(2-)}}
 |-
-| [[Superoxide]]
+| [[Acetylide]] || {{chem2|C2(2-)}}
-| {{chem2|O2(-)}}
+| [[Phenolate]] || {{chem2|C6H5O-}}
+| [[Benzoate]] || {{chem2|C6H5COO-}} or {{chem2|C7H5O2-}}
+| [[Chromate and dichromate|Chromate]] || {{chem2|CrO4(2-)}}
+| [[Superoxide]] || {{chem2|O2-}}
 |-
-| [[Hydroxide]]
+| [[Cyanide]] || {{chem2|CN-}}
-| {{chem2|OH-}}
+| [[tert-Butoxide|''tert''-Butoxide]] || {{chem2|(CH3)3CO-}}
+| [[Oxalate]] || {{chem2|C2O4(2-)}}
+| [[Chromate and dichromate|Dichromate]] || {{chem2|Cr2O7(2-)}}
+| [[Azanide]] || {{chem2|NH2-}}
 |-
-| [[Bisulfide]]
+| [[Cyanate]] || {{chem2|OCN-}}
-| {{chem2|SH-}}
+| colspan=2 rowspan=2 |
+| [[Citrate]] || {{chem2|C6H5O7(3-)}}
+| [[Tungstate|Orthotungstate]] || {{chem2|WO4(2-)}}
+| [[Orthosilicate]] || {{chem2|SiO4(4-)}}
 |-
-| [[Cyanate]]
+| [[Thiocyanate]] || {{chem2|SCN-}}
-| {{chem2|OCN-}}
+| colspan=2 |
-|-
+| colspan=2 |
-| [[Thiocyanate]]
+| [[Borohydride]] || {{chem2|BH4-}}
-| {{chem2|SCN-}}
-|-
-| [[Orthosilicate]]
-| {{chem2|SiO4(4-)}}
-|-
-| [[Thiosulfate]]
-| {{chem2|S2O3(2-)}}
-|-
-| [[Azide]]
-| {{chem2|N3(-)}}
-|-
-| [[Tetraperoxochromate]]
-| {{chem2|Cr(O2)4(3-)}}
 |}
@@ Line 350: / Line 232: @@
 | [[Fluoronium]]
 | {{chem2|H2F+}}
-|[[Triphenylguanidinium]]<ref>{{Cite journal |last=Silva |first=Pedro S. Pereira |last2=Gonçalves |first2=Mauro A. Pereira |last3=F. Campos |first3=Nuno M. |last4=Paixão |first4=José A. |last5=Silva |first5=Manuela Ramos |date=2025-04-03 |title=Charge density and quantum-chemical study of triphenylguanidine and triphenylguanidinium trifluoroacetate |url=https://link.springer.com/article/10.1007/s11224-025-02491-w |journal=Structural Chemistry |language=en |doi=10.1007/s11224-025-02491-w |issn=1572-9001|doi-access=free }}</ref>
+|
-|[(C<sub>6</sub>H<sub>5</sub>)NH]<sub>3</sub>C<sup>+</sup>
+|
 |
 |
@@ Line 371: / Line 253: @@
 == Zwitterion and polycharged polyatomic ions ==
-Many polyatomic molecules can carry spatially separated charges, forming zwitterions or, in general, polycharged polyatomic ions. A typical example are [[amino acid]]s, which carry both charged amino and carboxyl groups. These charges can influence the chemical<ref>{{Cite journal |last=Pizzi |first=Andrea |last2=Dhaka |first2=Arun |last3=Beccaria |first3=Roberta |last4=Resnati |first4=Giuseppe |date=2024-07-01 |title=Anion⋯anion self-assembly under the control of σ- and π-hole bonds |url=https://pubs.rsc.org/en/content/articlelanding/2024/cs/d3cs00479a |journal=Chemical Society Reviews |language=en |volume=53 |issue=13 |pages=6654–6674 |doi=10.1039/D3CS00479A |issn=1460-4744|doi-access=free |url-access=subscription }}</ref>  and physical properties of substances.<ref>{{Cite journal |last=Novikov |first=Anton P. |last2=Safonov |first2=Alexey V. |last3=German |first3=Konstantin E. |last4=Grigoriev |first4=Mikhail S. |date=2023-12-18 |title=What kind of interactions we may get moving from zwitter to “dritter” ions: C–O⋯Re(O4) and Re–O⋯Re(O4) anion⋯anion interactions make structural difference between L-histidinium perrhenate and pertechnetate |url=https://pubs.rsc.org/en/content/articlelanding/2024/ce/d3ce01164j |journal=CrystEngComm |language=en |volume=26 |issue=1 |pages=61–69 |doi=10.1039/D3CE01164J |issn=1466-8033|url-access=subscription }}</ref>
+Many polyatomic molecules can carry spatially separated charges, forming polycharged polyatomic ions. An important case of these compounds are [[zwitterion]]s, which are neutral compounds but have opposing [[formal charge]]s within the same molecule.<ref>{{GoldBookRef|title=Zwitterions|file=Z06752}}</ref> A typical example are [[amino acid]]s, which carry both charged amino and carboxyl groups. These charges can influence the chemical<ref>{{Cite journal |last1=Pizzi |first1=Andrea |last2=Dhaka |first2=Arun |last3=Beccaria |first3=Roberta |last4=Resnati |first4=Giuseppe |date=2024-07-01 |title=Anion⋯anion self-assembly under the control of σ- and π-hole bonds |journal=Chemical Society Reviews |language=en |volume=53 |issue=13 |pages=6654–6674 |doi=10.1039/D3CS00479A |pmid=38867604 |issn=1460-4744|doi-access=free }}</ref>  and physical properties of substances.<ref>{{Cite journal |last1=Novikov |first1=Anton P. |last2=Safonov |first2=Alexey V. |last3=German |first3=Konstantin E. |last4=Grigoriev |first4=Mikhail S. |date=2023-12-18 |title=What kind of interactions we may get moving from zwitter to "dritter" ions: C–O⋯Re(O4) and Re–O⋯Re(O4) anion⋯anion interactions make structural difference between L-histidinium perrhenate and pertechnetate |url=https://pubs.rsc.org/en/content/articlelanding/2024/ce/d3ce01164j |journal=CrystEngComm |language=en |volume=26 |issue=1 |pages=61–69 |doi=10.1039/D3CE01164J |bibcode=2023CEG....26...61N |issn=1466-8033|url-access=subscription }}</ref>
+Many zwitterions exhibit [[tautomer]]ism with a "parent" molecule without formal charges. For example, [[glycine]] reversibly converts between the parent molecule and a zwitterionic form by transfer of a [[labile]] [[hydrogen]] atom between the protonated amino group and [[carboxylate]] group.<ref>{{cite journal|last1=Tuñón |first1=Iñaki |last2=Silla |first2=Estanislao |last3=Ruiz-López |first3=Manuel F. |title=On the tautomerization process of glycine in aqueous solution |journal=Chemical Physics Letters |date=2000 |volume=321 |issue=5–6 |pages=433–437 |doi=10.1016/S0009-2614(00)00365-1 |bibcode=2000CPL...321..433T }}</ref> By contrast, [[trimethylglycine]] has three non-labile [[methyl]] groups, making [[quaternary ammonium]], so it does not interconvert with the non-zwitterionic [[isomer]] (a [[dimethylglycine]] [[ester]]). These non-tautomeric zwitterions are called [[betaine]]s.<ref>{{GoldBookRef|title=Betaines|file=B00637}}</ref>
 == Applications ==

Polyatomic ion: Difference between revisions

Latest revision as of 16:09, 5 September 2025

Nomenclature of polyatomic anions

Naming oxyanions

Other examples of common polyatomic ions

Zwitterion and polycharged polyatomic ions

Applications

See also

References

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