Ammonium

Ammonium
Names
	IUPAC name Ammonium ion
	Systematic IUPAC name Azanium
Identifiers
CAS Number	14798-03-9 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:28938;
ChemSpider	218;
Gmelin Reference	84
KEGG	C01342;
MeSH	D000644
PubChem CID	16741146;
UNII	54S68520I4 ;
CompTox Dashboard (EPA)	DTXSID5043974 ;
	InChI InChI=1S/H3N/h1H3/p+1 Key: QGZKDVFQNNGYKY-UHFFFAOYSA-O; InChI=1/H3N/h1H3/p+1 Key: QGZKDVFQNNGYKY-IKLDFBCSAZ;
	SMILES [NH4+];
Properties
Chemical formula	[NH4]+
Molar mass	18.039 g·mol−1
Acidity (pKa)	9.25
Conjugate base	Ammonia
Structure
Molecular shape	Tetrahedral
Related compounds
Other cations	Phosphonium [PH4]+; Arsonium [AsH4]+; Hydronium [H3O]+; Sulfonium [H3S]+; Fluoronium [H2F]+; Chloronium [H2Cl]+; Bromonium [H2Br]+; Iodonium [H2I]+; Carbonium [CH5]+; Trihydrogen cation [H3]+;
Related compounds	Ammonium radical •NH4
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) molecular ion with the chemical formula NH+4 or [NH₄]⁺. It is formed by the addition of a proton (a hydrogen nucleus) to ammonia (NH₃). Ammonium is also a general name for positively charged (protonated) substituted amines and quaternary ammonium cations ([NR₄]⁺), where one or more hydrogen atoms are replaced by organic or other groups (indicated by R). Not only is ammonium a source of nitrogen and a key metabolite for many living organisms, but it is an integral part of the global nitrogen cycle. As such, human impact in recent years could have an effect on the biological communities that depend on it.