We'll go down to the column on the periodic table and group one and look at sodium. Like the lithium, the sodium is stored on a mineral oil to minimize reaction with the oxygen in the air. If we remove a piece of sodium metal, we notice that it is also coated over with an oxide coating. Sodium metal becomes softer as you go down the column. The sodium is much easier to cut than the lithium. As we cut off the oxide layer, we can see the shiny metal underneath. It coats over very rapidly with a layer of oxide. The sodium is a metal and is an excellent conductor of electricity. If we take a piece of the sodium metal and add it to water, we notice a much more rapid reaction with the water. Like lithium, the sodium is less dense in water and floats. The metal moves across the surface being pushed by the hydrogen gas that is produced. As you go down the column with group one metals, the melting point of the metal decreases. The reaction is very exothermic, which causes the sodium metal to melt. The metal contracts into a very compact spherical form. We can again test that hydrogen gas is being produced by this single displacement reaction by trapping the gas and testing its flammability. We can test for the fact that we produce sodium hydroxide by adding phenothylene. The phenothylene turns a purple red color due to the presence of the hydroxide ions indicating the formation of the sodium hydroxide.