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A polyatomic ion is an ion consisting of multiple atoms associated together by covalent bonds which can be considered as acting as a single unit in the context of acid/ base chemistry or in the formation of salts. Note that in this context, a polyatomic ion is also referred to in older works as a radical. In current usage the term radical refers to free radicals which are uncharged species with an unpaired electron.Some commonly-occurring polyatomic ions and their charges are
indicated below:
- carbonate CO32-
- bicarbonate HCO3-
- nitrate NO3-
- phosphate PO43-
- sulfate SO42-
- sulfite SO32-
- acetate CH3C(=O)O-
- ammoniumAmmonium is a polyatomic ion that behaves like an alkali metal. It is found ionized in various salts, such as ammonium bicarbonate and ammonium chloride, and also in urine. Dissolving ammonia in water produces ammonium hydroxide. Ammonium has been isolate NH4+
- hydroxideHydroxide is a functional group consisting of oxygen and hydrogen: :-O−H It has a charge of 1-. The term hydroxyl group is used when the functional group -OH is counted as a substituent of an organic compound. Organic molecules containing a hydroxyl OH-
- cyanideA cyanide is any chemical compound that contains the group C≡N, with the carbon atom triple bonded to the nitrogen atom. Inorganic cyanides contain the highly toxic cyanide ion C N- and are the salts of the acid hydrogen cyanide ( HCN). Organic cyan CN-
- pyridiniumPyridinium is the protonated form of pyridine. The lone pair of electrons on the nitrogen atom of pyridine is not delocalized, and thus pyridine can be protonated easily. Pyridine is often used as an organic base in chemical reations, thus the pyrindium i C5H5NH+
The atoms of a polyatomic ion are always associated with
each other via covalent or coordinate-covalent bondIn chemistry, a chemical bond is the force which holds together atoms in molecules or crystals. In many simple compounds, valence bond theory and the concept of oxidation number can be used to predict molecular structure and composition. Similarly, theoris.
A polyatomic ion that is primarily associated with other atoms by
covalent, rather than ionic, forces might more properly be referred to as a functional groupIn ecology functional groups are collections of organisms based on morphological, physiological, behavioral, biochemical, or environmental responses or on trophic criteria. In organic chemistry functional groups are submolecular structural motifs, charact.
Note that many of the common negatively-charged (anionic) polyatomic ions are oxideAn oxide is a chemical compound of oxygen with other chemical elements, e. rust ( iron oxide) or bauxite ( aluminium oxide). Oxides are extremely common in Earth's crust, and indeed in solid matter throughout the universe. Oxides are usually created throus of non-metallic elements, and can be considered the conjugate bases of the corresponding acids.
Bicarbonate is also called hydrogen carbonate in modern chemical nomenclatureNomenclature is a system of naming and categorizing objects in a given category. Linnaeus popularised one of the best-known examples: he used the binomial nomenclature system to name the biological world of animals and plants. In chemistry, the IUPAC nome.
Ions
