CBSE Class 9 Answered
A polyatomic ion is 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-, similarly SO42-, NH4+.
Ion: The atoms or groups of atoms which carry a positive charge or a negative charge are known as ions.
Metallic element: Elements have a tendency to lose their valence electrons and form a positive ion.
Eg. Na+, Mg+2
Non-metallic element: Elements have a tendency to gain electrons and form a negative ion.
Eg. Cl-, F-