* Physical changes alter the form or appearance of a substance but not its chemical composition. When you melt salt, you are changing its state from solid to liquid, but the chemical bonds between the sodium and chlorine ions remain intact. The salt is still sodium chloride (NaCl) in its liquid form.

* Chemical changes result in the formation of new substances with different chemical compositions. Melting salt does not create any new substances.

Here's an analogy: Think of ice melting into water. The water is still H2O, just in a different state. Similarly, molten salt is still NaCl.