Biological role. Potassium is essential to life. Potassium ions are found in all cells. It is important for maintaining fluid and electrolyte balance. Plant cells are particularly rich in potassium, which they get from the soil. Agricultural land, from which harvests are taken every year, needs to have its potassium replenished by adding potassium-based fertilisers. The average human consumes up to 7 grams of potassium a day, and stores about grams in the body cells.
A normal healthy diet contains enough potassium, but some foods such as instant coffee, sardines, nuts, raisins, potatoes and chocolate have above average potassium content. The naturally occurring isotope potassium is radioactive and, although this radioactivity is mild, it may be one natural cause of genetic mutation in humans. Natural abundance.
It makes up 2. There are deposits of billions of tonnes of potassium chloride throughout the world. Mining extracts about 35 million tonnes a year. Most potassium minerals are found in igneous rocks and are sparingly soluble. The metal is difficult to obtain from these minerals. There are, however, other minerals such as sylvite potassium chloride , sylvinite a mixture of potassium and sodium chloride and carnallite potassium magnesium chloride that are found in deposits formed by evaporation of old seas or lakes.
The potassium salts can be easily recovered from these. Potassium salts are also found in the ocean but in smaller amounts compared with sodium. Help text not available for this section currently. Elements and Periodic Table History. Potassium salts in the form of saltpetre potassium nitrate, KNO 3 , alum potassium aluminium sulfate, KAl SO 4 2 , and potash potassium carbonate, K 2 CO 3 have been known for centuries.
They were used in gunpowder, dyeing, and soap making. They were scraped from the walls of latrines, manufactured from clay and sulfuric acid, and collected as wood ash respectively. Then in , Humphry Davy exposed moist potash to an electric current and observed the formation of metallic globules of a new metal, potassium.
He noted that when they were dropped into water they skimmed around on the surface, burning with a lavender-coloured flame. Atomic data. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom.
Oxidation states and isotopes. Glossary Data for this section been provided by the British Geological Survey.
Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk. Recycling rate The percentage of a commodity which is recycled. Substitutability The availability of suitable substitutes for a given commodity.
Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators. Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.
Supply risk. Relative supply risk 4. Young's modulus A measure of the stiffness of a substance. Shear modulus A measure of how difficult it is to deform a material. Bulk modulus A measure of how difficult it is to compress a substance. Vapour pressure A measure of the propensity of a substance to evaporate. Pressure and temperature data — advanced.
Listen to Potassium Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry.
Hello, this week the story of the first alkaline metal ever isolated, why it's an alkaline metal at all and why its symbol begins with the letter K. Here's Peter Wothers. Potassium - the only element named after a cooking utensil. It was named in by Humphry Davy after the compound from which he isolated the metal, potash, or potassium hydroxide. An extract from the s by the Dutch chemist Herman Boerhaave describes how potash got its name:.
It is prepared there from the Wood of green Fir, Pine, Oak, and the like, of which they make large piles in proper Trenches, and burn them till they are reduced to Ashes These ashes are then dissolved in boiling Water, and when the Liquor at top, which contains the Salt, is depurated, i. This, then, is immediately put into large copper Pots, and is there boiled for the space of three days, by which means they procure the Salt they call Potas, which signifies Pot-Ashes on account of its being thus made in Pots.
Even earlier in the 16th Century, Conrad Gesner tells us that "Of the hearbe called Kali, doe certayne prepare a Salt". He describes this plant, Kali whose Latin name is Salsola kali but is more commonly known as Saltwort:. His method of production of this Salt of Alkali is pretty similar to that described by Boerhaave with both processes actually yielding an impure mixture of what we would now call potassium and sodium carbonate; the wood ash method yielding more potassium carbonate, potash, the salty herbs giving more sodium carbonate, soda.
However, it is from the herb kali, that we owe the word that describes both - al-kali or alkali; the 'al' prefix simply being Arabic definite article 'the'. The crude potash can be made more caustic or 'pure' by treating a solution of it with lime water, calcium hydroxide. The potassium carbonate and calcium hydroxide solutions react with a bit of chemical partner-swapping: insoluble calcium carbonate or chalk precipitates out, leaving a solution of potassium hydroxide.
It was from this pure hydroxide that Davy first isolated the metal potassium. Potassium is pronounced as poh-TASS-ee-em. Although potassium is the eighth most abundant element on earth and comprises about 2. Metallic potassium was first isolated by Sir Humphry Davy in through the electrolysis of molten caustic potash KOH. A few months after discovering potassium, Davy used the same method to isolate sodium. These minerals are often found in ancient lake and sea beds. Caustic potash, another important source of potassium, is primarily mined in Germany, New Mexico, California and Utah.
Pure potassium is a soft, waxy metal that can be easily cut with a knife. Because potassium forms salts so easily, many of the ions in salt water are potassium ions. You may even find trace amounts in freshwater sources. Nuclear Reactors As you learn more about chemistry, you will learn that many of the simple elements are involved in nuclear reactors and radioactive experiments.
You can even find radioactive isotopes of potassium that are used in research. Potassium metal rarely is used for anything, because sodium will do the same things potassium will do and sodium is a lot cheaper. Potassium compounds are used in glass, soaps, explosives, baking powder, tanning lotions, and especially in fertilizers.
Similar to sodium, potassium is critical to all living things, for the same reasons i. The potassium ion is used extensively in intercellular fluids. Potassium plays an important role in the growth of plants.
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