FREE ESSAY ON POTASSIUM

POTASSIUM

potassium
puh-tas'-ee-uhm
The chemical element potassium is a soft, light, silver white metal. It is a member of
the alkali metals, a group (IA of the periodic table) with similar physical and chemical
properties. Its chemical symbol is K (from kalium, the Latinized version of the Arabic
word for alkali). Its atomic number is 19, and its atomic weight is 39.098.
Potassium was first made from potash, or potassium carbonate (K(2)CO(3)), which had
important industrial uses in glass manufacture well before 1700. (It was often mistaken
for sodium carbonate, or soda. Only their different sources prevented total confusion,
potash being originally derived from the ashes of vegetable materials, whereas sodium
carbonate is most often found as a mineral.) On Oct. 6, 1807, Sir Humphry Davy connected
a piece of solid potash to the poles of a battery and caused the release of a metal at
the negative pole. He named the metal potassium and determined many of its physical and
chemical properties.
Chemical Properties
Alkali metals are the most reactive metals. In general, their reactivity increases with
increase in atomic size. Because of their electron arrangement and relatively large size
and small charge, potassium atoms are conducive to ion formation only by ionic bonds. 
Biological Role
Potassium is essential to life. Involved in active transport, the process of moving
substances in and out of cells, it constitutes about 0.06% of the atoms in the human
body. Whereas sodium ions are found primarily in intercellular fluids, about 99% of the
body's potassium lies within the cells. Together, these ions help to regulate cellular
osmotic pressure and acidity, or pH, levels. Potassium plays a key role in muscle
activity and the transmission of nerve impulses. It is also involved in cellular enzyme
functions. An abnormally low level of potassium in blood serum causes cardiac
abnormalities, and an abnormally high level leads to a heart attack. Such changes in
level, controlled by the kidneys, can result from various diseases. Potassium is present
in most food substances, so a potassium-deficient diet is unlikely.
Production
Potassium is produced in laboratory amounts by electrolytic reduction of fused potassium
hydroxide (KOH) or fused potassium chloride (KCl). Other methods include electrolysis of
fused potassium cyanide (KCN), heating potassium chloride (KCl) with metallic calcium in
a vacuum and distilling the potassium as it is formed, and heating potassium hydroxide
(KOH) with iron, aluminum, or magnesium. Because commercial potassium uses are most often
also satisfied by more easily recovered sodium, only modest amounts of potassium are
produced. One industrial method uses sodium vapor to reduce molten potassium chloride at
880 degrees C. The potassium vapor formed is drawn off and condensed.
Potassa potash, from English potash]
First appeared circa 1807
: a silver-white soft light low-melting univalent metallic element of the alkali metal
group that occurs abundantly in nature esp. combined in minerals
potassium 
Dutch potassa 'potash' 
Soft, waxlike, silver-white, metallic element, symbol K (Latin kalium), atomic number 19,
relative atomic mass 39.0983. It is one of the alkali metals and has a very low density -
it floats on water, and is the second lightest metal (after lithium). It oxidizes rapidly
when exposed to air and reacts violently with water. Of great abundance in the Earth's
crust, it is widely distributed with other elements and found in salt and mineral
deposits in the form of potassium aluminium silicates.
Potassium is the main base ion of the fluid in the body's cells. Along with sodium, it is
important to the electrical potential of the nervous system and, therefore, for the
efficient functioning of nerve and muscle. Shortage, which may occur with excessive fluid
loss (prolonged diarrhoea, vomiting), may lead to muscular paralysis; potassium overload
may result in cardiac arrest. It is also required by plants for growth. The element was
discovered and named in 1807 by English chemist Humphry Davy, who isolated it from potash
in the first instance of a metal being isolated by electric current.