Potassium is a soft, silvery coloured metal, which like other members of the alkali group of metals, is extremely reactive.  As with other members of the group, it can be prepared by electrolysis of the fused halide.  It is one of the more common alkali metals, there being 26000 ppm in the earth's crust, the main source being potassium chloride.  Potassium is the seventh most abundant element on earth.  It is one of the most reactive and electropositive of all metals and rapidly oxidizes.  As with other alkali metals, potassium decomposes in water with the evolution of hydrogen because of its reacts violently with water, it only occurs in nature in ionic salts.  Potassium Bohr Model In its elemental form, potassium has a silvery gray metallic appearance, but its compounds (such as potassium hydroxide) are more frequently used in industrial and chemical applications.  It does not occur naturally.  Potassium has limited use as the pure metal, although it can be used with sodium as a coolant in liquid metal reactors.  It is more commonly used as a salt;