(a) The formula for bromate ion (BrO₃^–) is similar to that of chlorate ion (ClO₃^–); however, the formulas of the nitrate and phosphate ions have different numbers of oxygen atoms, as do the formulas of the nitrite and phosphite ions. Draw the Lewis structures of all four ions and explain why the formulas differ.

(b) Energy is supplied to muscles in the body through changes in ATP, a molecule that contains chains of phosphate ions (—PO₂ —O—PO₂ —O—PO₂ —O—). Explain how phosphate ions can connect to one another in this way, but nitrate ions cannot.