Potassium Essay, Research Paper

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.