CBSE Class 12-science Answered
The bond formed between two atoms by sharing a pair of electrons provided entirely by one of the combining atoms but shared by both is called a coordinate bond or dative bond.
Examples: Ammonium ion (NH4+), hydronium ion (H3O+)
A coordinate bond has properties of both covalent and ionic bonds. So, it is also called a co-ionic bond.
When a single atom shared its electrons pair to other atom the bond formed is coordinate covalent bond