Atomic Number: 19
Atomic Symbol: K
Atomic Weight: 39.098
Electron Configuration: [Ar]4s1

History
(English, potash - pot ashes; L.. kalium, Arab qali, alkali) Discovered in 1807 by Davy, who obtained it from caustic potash (KOH); this was the first metal isolated by electrolysis.

Sources
The metal is the seventh most abundant and makes up about 2.4% by weight of the earth's crust. Most potassium minerals are insoluble and the metal is obtained from them only with great difficulty.

Certain minerals, however, such as sylvite, carnallite, langbeinite, and polyhalite are found in ancient lake and sea beds and form rather extensive deposits from which potassium and its salts can readily be obtained. Potash is mined in Germany, New Mexico, California, Utah, and elsewhere. Large deposits of potash, found at a depth of some 3000 ft in Saskatchewan, promise to be important in coming years.

Potassium is also found in the ocean, but is present only in relatively small amounts, compared to sodium.

Production
Potassium is never found free in nature, but is obtained by electrolysis of the hydroxide, much in the same manner as prepared by Davy. Thermal methods also are commonly used to produce potassium (such as by reduction of potassium compounds with CaC2, C, Si, or Na).

Uses
The greatest demand for potash has been in its use for fertilizers. Potassium is an essential constituent for plant growth and is found in most soils.

An alloy of sodium and potassium (NaK) is used as a heat-transfer medium. Many potassium salts are of utmost importance, including the hydroxide, nitrate, carbonate, chloride, chlorate, bromide, iodide, cyanide, sulfate, chromate, and dichromate.

Properties
It is one of the most reactive and electropositive of metals. Except for lithium, it is the lightest known metal. It is soft, easily cut with a knife, and is silvery in appearance immediately after a fresh surface is exposed. It rapidly oxidizes in air and must be preserved in a mineral oil such as kerosene.

As with other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It catches fire spontaneously on water. Potassium and its salts impart a violet color to flames.

Isotopes
Seventeen isotopes of potassium are known. Ordinary potassium is composed of three isotopes, one of which is 40K (0.0118%), a radioactive isotope with a half-life of 1.28 x 109 years.

Handling
The radioactivity presents no appreciable hazard.

Sources: CRC Handbook of Chemistry and Physics and the American Chemical Society.












    What Topic Is Your Chemistry Paper On?  

 ENTER YOUR TOPIC HERE:    
Over 70,000 Research Papers, Essays & Term Papers - Ready to Download!

<Navigation>


Search!


<Index>

Acoustics
Agriculture
Anthropology
Archaeology
Architecture
Biology
Biotechnology
Cancer
Chemistry
Composers
Dance
Electronics
Environment
Fine Art
Geology
Invertebrate
Plant
Political Science
Psychology
Scientists
Sociology


<Top Level>

WebRef.org
About Us
Copyright Notice
Privacy Statement


Iverson Software: Providing Reliable & Innovative Education Solutions since 1987!

About Us  Success Tools 

Google
Search WWW Search webref.org


K12 Shipping
JourneyEd.com is the leading supplier of discounted software to students and faculty.

icon

Iverson Software Co., is not responsible for typographical errors. Information deemed to be accurate, but not guaranteed. Offers subject to change at any time. Copyright © 1987-2011 Iverson Software Co. Some material copyright of their respective holders. All Rights Reserved Worldwide.