Potassium was first isolated from caustic potash KOH (molten) by electrolysis in 1807. It was done by Sir Humphry Davy. Potassium collected at the cathode.
Potassium is the seventh most abundant element found on Earth’s crust. It constitutes 2.6 percent of Earth’s mass. The element whose atomic number is 19 and atomic weight 39.098u has a melting point of 63.28°C and a boiling point of 760°C. Its specific gravity is 0.862 at 20°C. Potassium has two oxidation states +1 and -1(rarely).
Since potassium is mainly present in igneous rocks, shale, and sediment in minerals like muscovite and orthoclase feldspar, it is difficult to procure the element itself. The fact that these minerals are insoluble in water makes the job tougher. Therefore, soluble potassium compounds such as carnallite (KMgCl3.6H2O), sylvite (KCl), polyhalite (K2Ca2Mg [SO4]4.2H2O), and langbeinite (K2Mg2 [SO4]3) which are found in ancient lake beds and sea beds are electrolyzed to obtain commercial compounds of potassium.
The element whose atomic number is 19 has 0.82 marking for electronegativity (according to Pauling). It has a density of 0.86 g.cm-3 at 0°C. It's Van der Waals radius measures to 0.235 nm. It has an ionic radius of 0.133 nm. The energy of the first isolation is 418.6 kJ.mol-1.
Since potassium forms a lot of compounds, it is a very useful element. Potassium chloride (KCl) can be called as the most common potassium compound. It is used in fertilizers and also as a salt substitute. It can be used to produce other chemicals as well. Potassium hydroxide (KOH) is used in the manufacture of soaps, detergents and drain cleaners. Potassium carbonate (KHCO3) is used to make certain types of glass and soaps. It is obtained as a byproduct of the commercial production of ammonia. KHCO3 is also known as pearl ash. Potassium nitrate (KNO3) is used in the production of fertilizers, match heads and also pyrotechnics.