Can we speak of molecular formulae in describing an ionic salt?

1 Answer
Aug 15, 2016

We use molecular formula to describe molecules; however, not all chemical substances are molecular. We would use an empirical formula to describe a salt.


Ionic species are definitely non-molecular. They consist of an infinite lattice of postive and negative ions that are held together by strong electrostatic bonds. In common salt, for every sodium cation, there is a correpsonding chloride anion; the charge is balanced by the pairing of postive and negative ions. The simplest formula that represents this is #NaCl#.

On the other hand, there are discrete molecular substances. Ethane consistes of discrete molecules of #H_3C-CH_3#. A simpler formula that represented the elemental makeup would be #CH_3#. However, because we have a very good idea of the mass of the molecule, we present the molecular formula as written.