Challenge In this exercise, you will draw diagrams to illustrate the formation of ionic compounds. 1 When calcium reacts with chlorine the compound calcium chloride is formed. The formula for calcium chloride is CaCl2. a Information you may need: Calcium has an atomic number of 20 and a mass number of 40. Chlorine has an atomic number of 17 and a mass number of 35. Draw diagrams to show the structures of calcium and chlorine atoms. Make sure you label the calcium and chlorine atoms. b Draw diagrams to show the ions of calcium and chlorine. Make sure you label the calcium and chlorine ions. ​