Exercise Write the formula of ionic compounds containing the ions of: a) Calcium and oxygen b) Lithium and sulfur c) Aluminum and oxygen d) Barium and iodine

a) The formula for the ionic compound containing calcium and oxygen is CaO. Calcium has a charge of +2 (Ca^2+) and oxygen has a charge of -2 (O^2-). When these ions combine, they form a neutral compound with the formula CaO.<br /><br />b) The formula for the ionic compound containing lithium and sulfur is Li2S. Lithium has a charge of +1 (Li^+) and sulfur has a charge of -2 (S^2-). To balance the charges, two lithium ions are needed for every sulfur ion, resulting in the formula Li2S.<br /><br />c) The formula for the ionic compound containing aluminum and oxygen is Al2O3. Aluminum has a charge of +3 (Al^3+) and oxygen has a charge of -2 (O^2-). To balance the charges, two aluminum ions are needed for every three oxygen ions, resulting in the formula Al2O3.<br /><br />d) The formula for the ionic compound containing barium and iodine is BaI2. Barium has a charge of +2 (Ba^2+) and iodine has a charge of -1 (I^-). To balance the charges, one barium ion is needed for every two iodine ions, resulting in the formula BaI2.