Polyatomic+ions

__Polyatomic Ions__ Polyatomic ions are two or more atoms covalently bound together, that have an overall negative or positive charge. Common polyatomic ions.

A **polyatomic ion**, also known as a **molecular ion**, is a charged [|species] ( [|ion] ) composed of two or more atoms [|covalently bonded] or of a [|metal complex] that can be considered as acting as a single unit in the context of [|acid] and [|base] [|chemistry] or in the formation of [|salts]. The prefix "poly-" means "many," in Greek, but even ions of two atoms are commonly referred to as polyatomic. In older literature, a polyatomic ion is also referred to as a ** [|radical] **, and less commonly, as a **radical group**. In contemporary usage, the term radical refers to [|free radicals] that are (not necessarily charged) species with an unpaired electron. For example, a [|hydroxide] ion is made of one oxygen atom and one hydrogen atom: its chemical formula is ( [|O] [|H] )−. It has a charge of [|−1]. An [|ammonium] ion is made up of one nitrogen atom and four hydrogen atoms: Its chemical formula is ( [|N] [|H] 4)+. It has charge of +1. A polyatomic ion can often be considered as the [|conjugate acid] or conjugate base of a neutral molecule. For example, the [|sulfate] anion, [|S] [|O] 42−, is derived from [|H2SO4], which can be regarded as [|SO3] + [|H2O].