Exercises: Properties of ionic compounds

Ionic compounds have high melting points, are hard but brittle, and conduct electric current when molten or dissolved in water, but not in the solid state. Choose two of these properties and explain them based on their structure: ions arranged in a lattice with strong attractions.

A homemade battery built with tap water lights up a small bulb, but with pure distilled water it does not. Using what you know about dissolved ionic compounds and the movement of charges, explain why ordinary water (with dissolved salts) conducts electricity and distilled water barely does.