Alkali metals include lithium, sodium, rubidium, cesium and francium. Those metals which are present in first group of the periodic table excluding hydrogen are called alkali metals. Alkali metals lose one electron from their outer most shell to become stable. When alkali metals lose an electron they get electronic configuration of inert gases. They have very low first ionization energy but have very high second ionization energy. Alkali metals are soft and have less density. Alkaline metals react with halogen, which are present in seventh group of periodic table, to form salts. Moreover, strong alkaline hydroxides are formed when alkali metals react with water.