A polyatomic ion are also known as a molecular ion.
These are 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.
Examples : a hydroxide ion is made of one oxygen atom and one hydrogen atom: its chemical formula is (OH)â, similarly SO42â, (NH4)+.
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