It's Elemental - The Element Potassium It's Elemental Melting Point: 336.53 K (63.38°C or 146.08°F) Boiling Point: 1032 K (759°C or 1398°F) Density: 0.89 grams per cubic centimeter Phase at Room Temperature: Solid Element Classification: Metal Period Number: 4 Group Number: 1 Group Name: Alkali Metal What's in a name? From the English word potash. Potassium's chemical symbol comes from the Latin word for alkali, kalium. Say what? Potassium is pronounced as poh-TASS-ee-em. History and Uses: Although potassium is the eighth most abundant element on earth and comprises about 2.1% of the earth's crust, it is a very reactive element and is never found free in nature. Metallic potassium was first isolated by Sir Humphry Davy in 1807 through the electrolysis of molten caustic potash (KOH). A few months after discovering potassium, Davy used the same method to isolate sodium .

Potassium can be obtained from the minerals sylvite (KCl), carnallite (KCl·MgCl2·6H2O), langbeinite (K2Mg2(SO4)3) and polyhalite (K2Ca2Mg(SO4)4·2H2O). 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. It reacts with oxygen to form potassium superoxide (KO2) and with water to form potassium hydroxide (KOH), hydrogen gas and heat. Enough heat is produced to ignite the hydrogen gas. To prevent it from reacting with the oxygen and water in the air, samples of metallic potassium are usually stored submerged in mineral oil. Potassium forms an alloy with sodium (NaK) that is used as a heat transfer medium in some types of nuclear reactors. Potassium forms many important compounds. Potassium chloride (KCl) is the most common potassium compound. It is used in fertilizers, as a salt substitute and to produce other chemicals.

Potassium hydroxide (KOH) is used to make soaps, detergents and drain cleaners. Potassium carbonate (KHCO3), also known as pearl ash, is used to make some types of glass and soaps and is obtained commercially as a byproduct of the production of ammonia. Potassium superoxide (KO2) can create oxygen from water vapor (H2O) and carbon dioxide (CO2) through the following reaction: 2KO2 + H2O + 2CO2 => 2KHCO3 + O2. It is used in respiratory equipment and is produced by burning potassium metal in dry air. Potassium nitrate (KNO3), also known as saltpeter or nitre, is used in fertilizers, match heads and pyrotechnics.

Estimated Crustal Abundance: 2.09×104 milligrams per kilogram Estimated Oceanic Abundance: 3.99×102 milligrams per liter Number of Stable Isotopes: 2 ( View all isotope data ) Ionization Energy: 4.341 eV Potassium (K) - Chemical properties, Health and Environmental effects Potassium The name is derived from the english word potash. The chemical symbol K comes from kalium, the Mediaeval Latin for potash, which may have derived from the arabic word qali, meaning alkali. Potassium is a soft, silvery-white metal, member of the alkali group of the periodic chart. Potassium is silvery when first cut but it oxidizes rapidly in air and tarnishes within minutes, so it is generally stored under oil or grease. It is light enough to float into water with which it reacts instantly to release hydrogen, which burns with a lilac flame. The chemistry of potassium is almost etirely that of the potassium ion, K+.

Applications Most potassium (95 %) goes into fertilizers and the rest goes mainly into making potassium hydroxide (KOH), by the electrolysis of potassium chloride solution, and then converting this to potassium carbonate (K2CO3). Potassium carbonate goes into glass manufacture, expecially the glass used to make televisions, while potassium hydroxide is used to make liquid soaps and detergents. A little potassium chloride goes into pharmaceuticals, medical drips and saline injections. Other potassium salts are used in baking, photography and tanning leather, and to make iodize salts. In all cases it is the negative anion, not the potassium, which is the key to their use. Potassium in the environment Most potassium occurs in the Earth's crust as minerals, such as feldspars and clays. Potassium is leached from these by weathering, which explains why there is quite a lot of this element in the sea (0.75 g/liter). Minerals mined for their potassium are pinkish and sylvite, carnallite and alunite. The main mining area used to be Germany, which had a monopoly of potassium before the first World War.

Today most potassium minerals come from Canada, USA and Chile. The world production of potassim ores is about 50 million tonnes, and reserves are vast (more than 10 billion tonnes). Potassium is a key plant element. Although it is soluble in water, little is lost from undisturbed soils because as it is released from dead plants and animal excrements, it quickly become strongly bound to clay particles, and it is retained ready to be readsorbed by the roots of other plants. Health effects of potassium Potassium can be found in vegetables, fruit, potatoes, meat, bread, milk and nuts. It plays an important role in the physical fluid system of humans and it assists nerve functions. Potassium, as the ion K+, concnetrate inside cells, and 95% of the body's potassium is so located. When our kidneys are somehow malfunctioning an accumulation of potassium will consist. This can lead to disturbing heartbeats. Potassium can effect you when breathed in. Inhalation of dust or mists can irritate the eyes, nose, throat, lungs with sneezing, coughing and sore throat. Higher exposures may cause a build up of fluid in the lungs, this can cause death.

Skin and eye contact can cause severe burns leading to permanent damage. Potassium - Element information, properties and uses | Periodic Table Chemistry in its element: potassium (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith 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. Peter Wothers Potassium - the only element named after a cooking utensil. It was named in 1807 by Humphry Davy after the compound from which he isolated the metal, potash, or potassium hydroxide. An extract from the 1730s by the Dutch chemist Herman Boerhaave describes how potash got its name: "Potas or Pot-ashes is brought yearly by the Merchant's Ships in great abundance from Coerland (now part of Latvia and Lithuania), Russia, and Poland.

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.e. freed from impurities, by standing quiet, it is poured off clear. 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: "Kali is of two Cubites of heygth, hauing no prickles or thornes, & is sometymes very red, saltye in taste, with a certayne vngratefull smell, found & gathered in saltie places: out of which, the Salt of Alkali maye be purchased" 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. To do this he used the relatively new force of electricity. After unsuccessfully trying to electrolyse aqueous solutions of potash, during which he only succeeded in breaking apart the water, he reasoned that he needed to do away with the water and try to electrolyse molten potassium hydroxide. This he did on the sixth of October, 1807 using the large Voltaic pile he had built at the Royal Institute in London. His younger cousin, Edmund Davy, was assisting Humphry at the time and he relates how when Humphry first saw "the minute globules of potassium burst through the crust of potash, and take fire as they entered the atmosphere, he could not contain his joy".

Davy had every right to be delighted with this amazing new metal: it looked just like other bright, shiny metals but its density was less than that of water. This meant the metal would float on water --at least, it would do if it didn't explode as soon as it came into contact with the water. Potassium is so reactive , it will even react and burn a hole through ice. This was the first alkali metal to be isolated, but Davy went on to isolate sodium, calcium, magnesium and barium. Whilst Davy named his new metal potassium after the potash, Berzelius, the Swedish chemist who invented the international system of chemical symbols now used by chemists the world over, preferred the name kalium for the metal, better reflecting its true origins, he thought. Hence it is due a small salty herb that we now end up with the symbol K for the element pot-ash-ium, potassium. Chris Smith Cambridge chemist Peter Wothers. Next time beautiful but deadly is the name of the game. Bea Perks Arsenic gets its name from a Persian word for the yellow pigment now known as orpiment.

For keen lexicographers apparently the Persian word in question Zarnikh was subsequently borrowed by the Greeks for their word arsenikon which means masculine or potent. On the pigment front, Napoleon's wallpaper just before his death is reported to have incorporated a so called Scheele's green which exuded an arsenic vapour when it got damp. Chris Smith So potent or not, licking the wallpaper in Napoleon's apartments is definitely off the menu. That's Bea Perks who will be with us next time to tell us the deadly tale of arsenic, I hope you can join us. I'm Chris Smith, thank you for listening and goodbye. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) Potassium 16.4 x 106 S m-1 Freezing/Melting point: 63.4 oC, 336.5 K Davy (on the bellows) at a public demonstration of science at the Royal Institution in London. Image by James Gillray. Sodium and then potassium reacting with water.

Discovery of Potassium Dr. Doug Stewart In 1806 English chemist Sir Humphry Davy discovered that chemical bonding was electrical in nature and that he could use electricity to split substances into their basic building blocks – the chemical elements. In 1807 he isolated potassium for the first time at the Royal Institution, London. He electrolyzed dried potassium hydroxide (potash) which he had very slightly moistened by exposing it to the moist air in his laboratory. The electrolysis was powered by the combined output of three large batteries he had built. When he applied a voltage from his batteries to the potassium hydroxide, he found globules “having a high metallic lustre” collected at the negatively charged electrode.

(1) Edmund Davy, who assisted in the experiment, described Sir Humphry Davy’s reaction to the production of potassium metal, his Eureka moment: “… when the minute globules of potassium burst through the crust of potash, and take fire as they entered the atmosphere, he could not contain his joy – he actually danced about the room in ecstatic delight; some little time was required for him to compose himself sufficiently to continue the experiment.” (2) Potassium was the first metal to be isolated by electrolysis. Davy was astonished at the new metal’s low density, observing that it floated on oil – something no other metal would do. He placed a piece of potassium in water and observed that the water, “decomposes it with great violence, an instantaneous explosion with brilliant flame. He also (bravely) added potassium to hydrochloric acid and saw it burn with a bright red flame. (3) The name potassium is from the English word ‘potash’, originally meaning an alkali extracted with water in a pot of ash of burned wood or tree leaves. Potassium’s symbol K comes from ‘kalium’ the name of the element in Germany and Scandinavia.

(4) Just a few days after isolating potassium, Davy isolated sodium for the first time using the same method. Interesting Facts about Potassium Potassium and its close periodic table neighbor sodium are solids at room temperature. Their alloys however are not. NaK alloys containing 40 to 90 percent of potassium by weight are liquids at room temperature. The commercially available 78% K, 22% Na alloy stays liquid at temperatures as low as -12.6 oC (9.3 oF). All living cells need potassium to maintain fluid balance, therefore we and all other forms of life on Earth need potassium minerals to survive. Potassium is available in all meats, plants and dairy products. Fruit and vegetables are the best sources of potassium. Several neurotoxins work by disrupting our cells’ biological use of potassium. This can result in severe pain, or even death. These neurotoxins include agitoxin, charybdotoxin and margatoxin (scorpion stings), apamin (bee stings), and dendrotoxin (mamba snake bites). Most of the universe’s potassium atoms were made in the final moments of giant stars as they exploded in supernovae.

Potassium is made in the oxygen burning shell of stars when they explode. This is not normal burning, of course; it is nuclear fusion. Potassium is made, along with several other elements including sulfur, and silicon, during explosive oxygen burning in supernovae. All plants need potassium to survive; over 90% of all human use of potassium compounds is in the manufacture of plant fertilizers. People whose diets are low in potassium can suffer from hypokalemia. Severe hypokalemia can be life threatening. Symptoms include irregular heartbeat, fatigue, muscle cramps and constipation. It is unusual for people to be deficient in potassium solely as a result of getting too little in their diets. Usually hypokalemia is caused by other issues such as diarrhea and/or vomiting, use of antibiotics, and kidney disease. Most people are familiar with carbon dating, which uses the decay of the radioactive carbon-14 isotope to find the ages of once-living things such as animal and plant matter. The radioactive isotope potassium-40 gives us a way of dating rocks. Potassium-40 decays to argon-40 and calcium-40 with a half-life of 1.25 billion years.

The ratio of potassium-40 to argon-40 trapped in rock is used to determine how long it is since the rock has solidified. Will potassium metal react with ice? The still image you see above might not be the whole story. advertisement Chemical Elements.com - Potassium (K) Contains an "Introduction to Tungsten", among other things If you know of any other links for Potassium, please let me know Bentor, Yinon. Chemical Element.com - Potassium. < For more information about citing online sources, please visit the MLA's Website . This page was created by Yinon Bentor. Use of this web site is restricted by this site's license agreement . Copyright © 1996-2012 Yinon Bentor. All Rights Reserved. Potassium, Chemical Element - reaction, water, uses, elements, examples, metal, gas, number poe-TAS-see-um Discovery and naming Early humans were familiar with potash, a potassium compound that forms when wood burns. Wood ashes were washed with water to dissolve the potash. It was then recovered by evaporating the water. Potash was often called vegetable alkali.

That name comes from the origin of the material ("vegetable" plants that contain wood) and the most important property of the material, alkali. The word alkali means a strong, harsh chemical that can be used for cleaning. Common household lye (such as Drano) is a typical alkali. The chemical name for potash is potassium carbonate (K 2 CO 3 ). Early humans also knew about a similar substance called mineral alkali. This material was made from certain kinds of rocks. But it also had alkali properties. "Mineral alkali" was also called soda ash. The modern chemical name for soda ash is sodium carbonate (Na 2 CO 3 ). For many centuries, people had trouble telling "vegetable alkali" and "mineral alkali" apart. The two materials looked and acted very much alike. For example, they could both be used as cleaning materials. The main difference between them was the source from which they came. It was not until the eighteenth century that chemists understood the difference between potash (vegetable alkali) and soda ash (mineral alkali).

By the late 1700s, chemists were reasonably sure that both potash and soda ash contained elements they had never seen. They tried to think of ways to break these compounds down into their elements. The first method that Davy tried was to pass an electric current through a water solution of one compound or the other. But no new element was ever formed. What Davy did not know was how active the elements potassium and sodium are. Both elements are freed when an electric current is passed through a water solution of potash or soda ash. But as soon as the element is formed, it reacts immediately with the water. The free element can never be recovered by this method. Then Davy thought of another way to separate potash and soda ash into their elements. He decided to use no water in his experiment. Instead, he melted a sample of potash and a sample of soda ash. Then he passed an electric current through the molten (melted) substances. He was amazed to see a tiny liquid droplet of metal formed in each case. The droplet was the first piece of potassium and sodium ever to be seen by a human.

Davy had his first success with potassium using this approach on October 6, 1807. A few days later he repeated his experiment with soda ash and produced pure sodium metal. Davy named these two elements after their much older names: potassium for "potash" and sodium for "soda ash." Physical properties Potassium is a soft, silvery-white metal with a melting point of 63°C (145°F) and a boiling point of 770°C (1,420°F). Its density is 0.862 grams per cubic centimeter, less than that of water (1.00 grams per cubic centimeter). That means that potassium metal can float on water. Chemically, though, that's not a good idea (see "Chemical properties" below). The melting point of potassium is very low for a metal. It will melt over the flame of a candle flame. Chemical properties Like the other alkali metals, potassium is very active. It reacts with water violently and gives off hydrogen gas: So much heat is produced in this reaction that the hydrogen gas actually catches fire and may explode. Floating potassium metal on the surface of water is not a good idea!

In that instance, the potassium would skip along the surface of the water. The skipping is caused by hydrogen gas produced in the reaction pushing the metal around. The potassium would soon catch fire, burn, and, perhaps, explode. Potassium reacts readily with all acids and with all non-metals, such as sulfur, chlorine, fluorine, phosphorus, and nitrogen. Occurrence in nature Potassium is the eighth most abundant element in the Earth's crust. Its abundance is estimated to be about 2.0 to 2.5 percent. It is just slightly less abundant than its alkali cousin, sodium. Potassium is less dense than water, so it can float on water. However, chemically, potassium reacts with water violently. It will give off hydrogen and eventually catch fire. Potassium occurs widely in many different minerals.

Some of the most important of these are sylvite, or potassium chloride (KCl); sylvinite, or sodium potassium chloride (NaCl KCl); carnallite, or potassium magnesium chloride (KCl MgCl 2 ); langbeinite, or potassium magnesium sulfate (K 2 SO 4 ○ 2MgSO 4 ); and polyhalite, or calcium magnesium potassium sulfate (2CaSO 4 ○ MgSO 4 ○ K 2 SO 4 ). Isotopes There are three naturally occurring isotopes of potassium, potassium-39, potassium-40, and potassium-41. Potassium-40 is radioactive. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. About ten artificial radioactive isotopes of potassium are known also.

A radioactive isotope is one that breaks apart and gives off some form of radiation. Artificially radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. Potassium-40 is of special interest to scientists. Potassium is widely distributed in nature in plants, animals, and rocks. That means that nearly everything on Earth contains at least a tiny amount of radioactive potassium-40. That includes the human body! About 0.012 percent of the potassium in the human body is radioactive potassium-40. However, that is not enough radiation to cause any harm. Radioactive potassium-40 in rocks can be used to measure the age of objects. When the isotope gives off radiation, it breaks down to an isotope of argon: A scientist can analyze a rock to see how much potassium-40 and how much argon-40 it contains. The older the rock, the more argon-40 and the less potassium-40 it contains. The younger the rock, the more potassium-40 and the less argon-40 it contains. One might wonder why argon gas does not escape into the atmosphere.

The answer is that argon gas is trapped within the solid rock. It is released only when the potassium-dating process is conducted. Extraction The word "potash" is still a widely used term for potassium compounds taken from the earth. But it no longer means potassium carbonate to most people. It can mean potassium sulfate (K 2 SO 4 ), potassium chloride (KCl), potassium nitrate (KNO 3 ), potassium hydroxide (KOH), or potassium oxide (K 2 O). People cling to "potash" because it is the term used in the manufacture of fertilizers. And fertilizers are far and away the most important use of potassium compounds today. Chemistry and the environment E nvironmentalists often say that everything in nature is related. Here is a good example of that principle: Potash was a widely used material in Colonial America. People used the compound to make soap, glass, and dozens of other products. At the time, potash was easy to get. All one had to do was burn a tree and collect potash from its ashes. The only problem was that a single tree does not produce much potash.

To get all the potash a family might need, one might have to burn dozens or hundreds of trees. Colonists did not worry too much about this problem. America in the 1700s was covered with trees. Few people thought about or cared about "saving the environment." If they ran out of trees, they just moved farther west. One can imagine what America would have looked like if Colonists continued this practice. Fortunately, they did not have to. In the 1780s, French chemist Nicolas Le Blanc (1742-1806) invented an inexpensive method for making soda ash. Le Blanc's method used salt, or sodium chloride (NaCl); limestone, or calcium carbonate (CaCO 3 ); and coal (pure carbon). These three materials are all common and inexpensive. The Le Blanc method of making soda ash is quick, easy, and cheap. Before long, soda ash had become one of the least expensive chemicals made artificially. In the United States, trees were no longer burned to get potash. The most important source of potash in the United States is a mine near Carlsbad, New Mexico, that produces sylvinite (KCl NaCl).

That mine produces about 85 percent of the potash mined in the United States. Potash is also produced from huge long-buried salt mine blocks formed when ancient seas evaporated (dried up). In Michigan, for example, potash is obtained Potassium bicarbonate is used in the production of soft drinks. by passing water into these mines. The water returns to the surface and is allowed to evaporate. Potassium compounds in the mine remain behind when the water has all evaporated. Potassium metal is produced by combining potassium chloride with sodium metal at high temperatures. But this method is of little interest because potassium metal has few uses. Uses Potassium metal is sometimes used as a heat exchange medium. A heat exchange medium is a material that picks up heat in one place and carries it to another place. Potassium metal is sometimes used as a heat exchange medium in nuclear power plants. There, heat is produced at the core, or center, of the reactor. Liquid potassium is sealed into pipes surrounding the core. As heat is given off, it is absorbed (taken up) by the potassium. The potassium is then forced through the pipes into a nearby room. In that room, the potassium pipes are wrapped around pipes filled with water.

The heat in the potassium warms the water. Eventually the water gets hot enough to boil. It changes into steam and is used to operate devices that generate electricity. Compounds By far the most important compound of potassium is potassium chloride (usually referred to as "potash," of course!). At least 85 percent of that compound is used to make synthetic (artificial) fertilizers. In 1996, about 1.5 billion kilograms (3.4 billion pounds or 1.7 million tons) of potassium chloride was produced in the United States for use in fertilizers. Many other potassium compounds are commercially important, although no use begins to compare with the amount of potash used for fertilizers. Some examples of other important potassium compounds are the following: Potassium is one of the three primary nutrients, or macronutrients, required by plants.

potassium bicarbonate, or baking soda (KHCO 3 ): baking powders; antacid (for upset stomach); food additive; soft drinks; fire extinguishers potassium bisulfite (KHSO 3 ): food preservative (but not in meats); bleaching of textiles and straw; wineand beer-making; tanning of leathers potassium bitartrate, or cream of tartar (KHC 4 H 4 O 6 ): baking powder; "tinning" of metals; food additive potassium bromide (KBr): photographic film; engraving potassium carbonate, or potash (K 2 CO 3 ): specialized glasses and soaps; food additive potassium chromate (K 2 CrO 4 ): dyes and stains (bright yellowish-red color); explosives and fireworks; safety matches; tanning of leather; fly paper potassium fluorosilicate (K 2 SiF 6 ): specialized glasses, ceramics, and enamels; insecticide potassium hydroxide, or caustic potash (KOH): paint remover; manufacture of specialized soaps; fuel cells and batteries; bleaching; food additive; herbicide potassium nitrate, or nitre, or saltpeter (KNO 

3 ): explosives, fireworks, matches, rocket fuel; manufacture of glass; curing of foods Potassium bicarbonate is an additive in fire extinguishers.

potassium pyrophosphate, or tetrapotassium pyrophosphate, or TKPP (K 4 P 2 O 7 ): soaps and detergents potassium sodium tartrate, or Rochelle salt (KNaC 4 H 4 O 6 ): baking powder; medicine; silvering of mirrors Health effects Potassium is essential to both plant and animal life. It is one of the three primary nutrients, or macronutrients, required by plants. Plants require relatively large amounts of potassium in order to grow and remain healthy. Potassium plays a number of important roles in the human body also. It helps control the proper balance of fluids in cells and body fluids. It is involved in the transmission of chemical messages between nerve cells and in the contraction of muscles. Potassium also helps in the digestion of food and in the proper function of the eyes. In many of these reactions, potassium and sodium work together to keep these functions performing properly. The average human who weighs 70 kilograms (150 pounds) has 140 grams (5 ounces) of potassium in his or her body. Normal daily intake of potassium is about 3.3 grams (0.1 ounce).

Since potassium occurs in all plants, humans normally do not have any problems getting enough of the element in their daily diet. Also read article about Potassium from Wikipedia User Contributions: Potassium»the essentials [WebElements Periodic Table] Element News Potassium: the essentials Potassium is a metal and is the seventh most abundant and makes up about 1.5 % by weight of the earth's crust. Potassium is an essential constituent for plant growth and it is found in most soils. It is also a vital element in the human diet. Potassium is never found free in nature, but is obtained by electrolysis of the chloride or hydroxide, much in the same manner as prepared by Davy. It is one of the most reactive and electropositive of metals and, apart from lithium, it is the least dense known metal. It is soft and easily cut with a knife. It is silvery in appearance immediately after a fresh surface is exposed. It oxidises very rapidly in air and must be stored under argon or under a suitable mineral oil. As do all the other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It usually catches fire during the reaction with water.

Potassium and its salts impart a lilac colour to flames. CAS Registry ID : 7440-09-7 The picture above shows the colour arising from a burning mixture of potassium chlorate (KClO3) and sucrose (only to be demonstrated by a professionally qualified chemist). The chemistry of potassium is dominated by electron loss to form K+. Cartoon by Nick D Kim ( [Science and Ink] , used by permission). Potassium: historical information Potassium was discovered by Sir Humphrey Davy in 1807 at England. Origin of name : from the English word "potash" (pot ashes) and the Arabic word "qali" meaning alkali (the origin of the symbol K comes from the Latin word "kalium"). Until the 18th century no distinction was made between potassium and sodium. This was because early chemists did not recognise that "vegetable alkali" (K2CO3, potassium carbonate, coming from deposits in the earth) and "mineral alkali" (Na2CO3, sodium carbonate, derived from wood ashes) are distinct from each other. Eventually a distinction was made.

Well before potassium was recognized as an element, potassium carbonate was mixed with animal fat to make soap. The carbonate was made by extracting wood ash with water before concentration by boiling - hence the name "potash" for potassium salts. Potassium was isolated in 1807 by Sir Humphry Davy, who obtained it through the electrolysis of very dry molten caustic potash (KOH, potassium hydroxide). Potassium collected at the cathode. Potassium was the first metal isolated by electrolysis. Davy isolated sodium by a similar procedure later in 1807. Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms.

Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for potassium is shown below. [See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.] Potassium around us Read more » Potassium salts are essential for both animals and plants. The potassium cation (K+) is the major cation in intracellular (inside cells) fluids (sodium is the main extracellular cation). It is essential for nerve and heart function. A normal diet containing reasonable amounts of vegetables contains all the potassium necessary. Potassium metal is far too reactive to be found uncombined in nature. The element is quite abundant and makes up about 1.5 % by weight of the earth's crust. Potassium is found extensively as potash (KOH). It is mined in Germany, USA, and elsewhere.

Minerals such as sylvite (KCl), carnallite, and langbeinite, are found in ancient lake and sea beds. That as Saskatchewan in Canada contains about 10,000,000,000 tonnes of potassium chloride. Potassium is found in seawater, but in relatively small amounts compared to sodium. Abundances for potassium in a number of different environments. More abundance data » Location Second ionisation energy : 3052 kJ mol‑1 Isolation Isolation : potassium would not normally be made in the laboratory as it is so readily available commercially. All syntheses require an electrolytic step as it is so difficult to add an electron to the poorly electronegative potassium ion K+. Potassium is not made by the same method as sodium as might have been expected. This is because the potassium metal, once formed by electrolysis of liquid potassium chloride (KCl), is too soluble in the molten salt.

cathode: K+(l) + e- → K (l) anode: Cl-(l) → 1/2Cl2 (g) + e- Instead, it is made by the reaction of metallic sodium with molten potassium chloride at 850°C. Na + KCl ⇌ K + NaCl This is an equilibrium reaction and under these conditions the potassium is highly volatile and removed from the system in a form relatively free from sodium impurities, allowing the reaction to proceed. Potassium isotopes Read more » Although Potassium only has two stable isotopes (K-39 and K-41), the long-lived radioisotope K-40 is often also regarded as a stable isotope. Potassium isotopes, mainly K-40 and K-41, are used to study the impact of potassium on the growth of plants and of the human cardiovascular system. Potassium - EniG. Periodic Table of the Elements POTASSIUM Relative atomic mass: 39.0983(1) Potassium was discovered by Sir Humphry Davy (GB) in 1807.

The origin of the name comes from the Arabic word qali meaning alkali (the origin of the symbol K comes from the Latin word kalium). It is a soft, waxy, silver-white metal. Fresh surfaces have a silvery sheen. Potassium quickly forms dull oxide coating on exposure to air. It reacts strongly with water and gives off a flammable gas. It also reacts violently with oxidants. Potasium occurs only in compounds. Potassium is found in minerals like carnallite [(KMgCl3).6H2O] and sylvite (KCl). Pure metal is produced by the reaction of hot potassium chloride and sodium vapours in a special retort. Pottasium is used as potash in making glass and soap and as saltpetre, potassium nitrate (KNO3) to make explosives and to colour fireworks in mauve. Potassium ions are vital to function of nerve and muscle tissues. The price of 90.2 % pure potassium metal is 90.20  for 5 g. PHYSICAL PROPERTIES

Question: What is the chemical symbol for the element Potassium?
Answer: K