19K Potassium

Year Discovered

1807

Discovered By

Sir Humphry Davy of England

Biological Rating

Necessary for all life.

Description

Potassium’s name is derived from the English word “potash”, a common name for potassium hydroxide. Potassium is a light, very soft, silvery-white metal. It is even more violently reactive with water than is sodium. It is so reactive with oxygen, that if exposed to air, it will tarnish to a grayish color in seconds. Potassium occurs with an abundant radioactive isotope, K40. Consequently, potassium metal is almost always faintly radioactive. Potassium metal rarely is used for anything, because sodium will do the same things potassium will do and sodium is a lot cheaper. Even so, potassium is very common, being the 7th most abundant element in the Earth’s crust. Potassium compounds are used in glass, soaps, explosives, baking powder, tanning lotions, and especially in fertilizers. Potassium’s symbol, K, comes from its Latin name kalium.

Biological Benefits

Similar to sodium, potassium is critical to all living things, for the same reasons (i.e. it is used in the functioning of the nervous system, heart and the brain). The potassium ion is used extensively in intercellular fluids. Potassium plays an important role in the growth of plants. A naturally occurring radioactive isotope of potassium, K40, is believed to be a major cause of mutation in the evolution of life. When no or low sodium salts are needed in a person’s diet, the substitute is almost always potassium salt. Bananas are a good natural source of dietary potassium.

Role in Life Processes

Critical for life processes in plants and animals.

Percentage Amount in the Human Body: 0.2%

Sources

Most potassium is obtained from evaporite salt deposits containing sylvite (potassium chloride). It is also obtained from the minerals alunite and carnallite. Orthoclase feldspar is a very common potassium-bearing mineral. Potassium also can be obtained from the electrolysis of potash (KOH). Potassium is mined in Russia, Canada, Germany, Israel, France and the USA.