Calcium oxide, $\mathrm{CaO}$, is an ionic compound.

Describe two limitations of using a ball-and-stick model to represent a giant ionic lattice.

Draw a dot-and-cross diagram to show the ions in calcium oxide. Show only the outer shell electrons.

A student investigates the electrolysis of concentrated copper(II) chloride solution.

Explain the formation of the products at each electrode during this electrolysis.

In your explanation, include:

• The names of the products formed at each electrode
• The identity of all the ions present in the solution and which electrodes they migrate to
• Balanced half-equations for the reactions occurring at each electrode.