Families contain elements with similar characteristics, usually determined by the number of electrons in the outer electron energy level. atomic number atomic mass symbol element name Alkali Metals The alkali metals have 1 valence electron. They're soft metallic solids, with characteristic metal properties of shiny luster and high thermal and electrical conductivities. The alkali metals have low densities and melting points, increasing and decreasing respectively with increasing atomic mass.
The alkali metal react vigorously with water, producing hydrogen gas and a solution of an alkali metal hydroxide. These reactions are very exothermic, in many cases generating enough heat to ignite the H , producing fire or sometimes even an explosion.
