Explain the formation of Coordinate Covalent bond with one example.

Explanation

Co-ordinate covalent bond is a special type of covalent bond and in which the shared pair of electrons are contributed by only one of the bonded atoms. This bond is represented by an arrow mark ("`to`"), pointing towards the acceptor atom. The atom which contributes electron pair for sharing is called donor atom and the atom which accepts the electron pair is called acceptor.
In order to form a co-ordinate bond between two atoms, one of the atoms should possess lone pair of electrons and the other atom should possess empty orbital .
Ex : Formation of Ammonium ion `(ZH_(4)^(+))` : Ammonium ion is formed by the union `NH_(3)` molecule with `H^(+)` ion. In `NH_(3)` molecule the central 'N' atom has one lone pair of electrons and `H^(+)` ion has empty orbital. Hence, N- atom of `NH_(3)` molecule donates its lone pair to the empty orbital of `H^(+)` ion, forming a co-ordinate covalent bond between them.