 If we go down the column in group two from easing to calcium, we see that the calcium is also stored in the air. Instead of being a shiny metal, the calcium is coated with a layer of the metal oxide. As you go down the column in group two, the metals tend to get harder. Calcium is malleable, but requires a great deal more force to shape it. Calcium is a metal and does conduct electricity. If we add the calcium metal to water, we get a much more rapid reaction of the calcium with water than the magnesium. The reaction is very exothermic. This is due to the lower ionization energy of the calcium. We get a single displacement reaction producing hydrogen gas and a formation of slightly soluble calcium hydroxide. We can test for the hydrogen gas by collecting some of the hydrogen gas in a test tube and testing its flammability. We can test for the presence of calcium hydroxide by adding phenithaline indicator. The indicator turns purple indicating that the solution is basic and that calcium hydroxide has been formed.