Potassium (K) is the 19th element on the periodic table. Potassium was discovered by Sir Humphry Davy in 1807. Sir Humphry Davy first isolated metallic Potassium through the electrolysis of molten caustic potash. The name Potassium is derived from the English word Potash which means pot ashes and from the Arabic word, Qali which means Alkali. It's symbol, K, comes from the Latin word Kalium which also means Alkali.
Potassium is the eighth most abundant element on earth and comprises about 2.1% of the earth's crust. However it is a very reactive element and is never found free in nature.
Potassium is very commonly used in medication. You need Potassium for the proper functioning of the heart, kidneys, muscles, nerves, and digestive system. Certain diseases remove Potassium from the body. Potassium supplements are taken to replace potassium losses and prevent potassium deficiency. https://medlineplus.gov/druginfo/meds/a601099.html
Potassium is one of the most important body minerals. It is one of the main blood minerals called electrolytes. http://hkpp.org/patients/potassium-health
Potassium can also be used in matches. When it comes to lighting a match you need Phosphorous, but when it comes to keeping the match burning, that is where Potassium comes into play. The heat generated from the phosphorus is enough to make the Potassium chlorate break down and release oxygen. This oxygen combines with sulfur, allowing the flame to burn for a longer time. http://www.discovery.com/tv-shows/mythbusters/about-this-show/how-matches-work/
Potassium was the first metal to be isolated using electrolysis. https://www.hobart.k12.in.us/ksms/PeriodicTable/potassium.htm
The human body uses Potassium to control regular heartbeat, build muscles, contract muscles, regulate blood pressure, and control the water evenly in body tissues and cells.