Question

why is the formula written for an ionic compound such as NaCl the empirical formula,rather than a molecular formula?

Answer 1

Ionic crystals, such as NaCl, crystallize in regular patterns in three dimensions. They actually have no molecular formula because they occur in the crystal as the separate ions and not as molecules. We could write it as Na_xCl_x where x is some number that depends upon the size of the NaCl crystal (x would be in the hundreds of thousands even for a small crystal) so we take the easy way out and write it as NaCl which indicates that no matter how large the crystal is there is a 1:1 ratio of Na to Cl ions.

Answer 2

thanks