Question

Question #9759d

Answer 1

The biggest difference between simple ionic compounds like NaCl and ones that contain polyatomic ions is that the latter usually have lower melting points.

A compound that has polyatomic ions forces a larger separation between positive and negative ionic charges. This generally makes the interactions weaker, so these materials have lower melting points than simple ionic salts.

In extreme cases, the materials can be ionic liquids at room temperature. You can read more about ionic liquids at http://en.wikipedia.org/wiki/Ionic_liquid