potassium

Traductions

• anglais

  Date : 1983

  Définition

  An element. State: solid; group: IA; atomic no.: 19; atomic wt.: 39.098; valence: 1; isotopes: 2 stable 1 radioactive. Potassium, m.p. 63.4 °C (146 °F), is one of the more reactive of the alkali-metal group. So-named from "potash" by Humphry Davy, the English chemist (1778-1829) who isolated the element in 1807 by electrolysis. Its salts, chiefly KCl, occur in many natural deposits; in the U.S., the most important are underground deposits in New Mexico, and in the dry beds of desert lakes in California (Searles Lakes) and Utah (Great Salt Lake). The Stassfurt beds in Germany are the chief European source; enormous deposits are located in Saskatchewan, Canada, and the Dead Sea contains great amounts of potassium chloride.

  Note :

  Elemental potassium is dangerous to handle, as it react strongly with both air and water, evolving heat and flammable hydrogen to form potassium hydroxide (KOH). It readily combines with halogens and other elements, and its principal uses are in the form of these compounds, as fertilizers and explosives. It is a vital element in plant nutrition and occurs widely in soils; it also has important cellular and metabolic functions in animal organisms. In combination with sodium (NaK), it is useful as a heat-tansfer agent. Among the more important compounds are the chloride (fertilizers); the carbonate, also called potash (glass technology); the nitrate and chlorate (explosives); and the permanganate (antiseptic). Many potassium compounds are also used in fireworks and as phosphors.

  Termes :

  1. potassium
  2. K

  [K] Symbol for the element potasium; it stands for the Latin kalium (« alkali »).