can NaCl bond be called polar covalent bond? I understand that it's ionic bond but Na is still sharing its electron with Cl. I am confused with Ionic and polar covalent bond.
The sodium and chlorine ions do not actually share their electrons. Instead, chlorine "takes" an electron from sodium. They are kept together in a crystal lattice by electrostatic interactions between the net +1 charge of Na and net -1 charge of Cl, thusly making the bond ionic. If they were truly sharing their electrons, then yes, it would be considered polar covalent. But if that also were true, then dissolving NaCl in water would be much more difficult as the sodium and chloride cannot be separated.
An example of a polar covalent bond will be between carbon and oxygen, say carbon monoxide CO. These two atoms actually share their electrons and make it more difficult to separate the two atoms.