5. Molecules and Compounds

Lithium forms ${\mathrm{Li}}^{+}$ ions and oxygen forms $O^2$ ions. Can a stable ionic compound be made from lithium and oxygen, and if so, what is its correct formula unit?

When zinc reacts with sulfur to form an ionic compound, what is the correct formula unit of the product?

In the ionic compound $Fe{C}_{l}3$ (iron(III) chloride), which ions and how many of each are present in one formula unit?