Ionic bonding happens when an atom of an element gives one or more of its electrons to the other element's atom..it usually takes place between metal and non metal atoms...like in NaCl, Na gives its valence electron to chlorine and completes its own octet. Chlorine accepts the electron and completes its own octet too...but now both the atoms have an opposing charge and hence they attract each other to form an IONIC bond.
Ionic bonds are the strongest of the bonds...here complete transfer of electrons takes place unlike covalent bonds.
