This article is about the type of compound. For the ion, seeinorganic peroxide.
Peroxides are a group ofmolecules with the structureR−O−O−R, where each R represents a radical (a portion of a complete molecule; not afree radical[1]) and the O's are singleoxygen atoms.[2][page needed][3][page needed] Oxygen atoms are joined to each other and to adjacent elements throughsingle covalent bonds, denoted by dashes or lines. TheO−O group in a peroxide is often called theperoxide group, though some nomenclature discrepancies exist. This linkage is recognized as a commonpolyatomic ion, and exists in many molecules.
The characteristic structure of any regular peroxide is the oxygen–oxygen covalent single bond, which connects the two main atoms together. Each oxygen atom has a oxidation state of negative one, as 5 of itsvalence electrons remain in the outermostorbital shell whilst one is occupied in thecovalent bond. Because of the nature of the covalent bond, this arrangement results in each atom having the equivalent of 7 valence electrons,reducing the oxygens and giving them a negative charge. This charge is affected by the addition of other elements, with the properties and structure changing depending on the added group(s).[citation needed]
The linkage between the oxygen molecules is known as aperoxy group (sometimes calledperoxo group,peroxyl group, of peroxy linkage). The nomenclature of the peroxy group is somewhat variable,[5] and exists as an exception to the rules of naming polyatomic ions. This is because, when it was discovered, it was believed to be monatomic.[6] The term was introduced byThomas Thomson in 1804 for a compound combined with as much oxygen as possible,[7] or the oxide with the greatest quantity of oxygen.[8]
