Thursday, May 5, 2011

What is silver

Silver is a metallic chemical element with the chemical symbol Ag  (Latin: argentum, from the Indo-European root *arg- for "grey" or "shining") and atomic number 47. Silver is a soft, white, lustrous transition metal that has the highest electrical conductivity of any element and the highest thermal conductivity of any metal.

The metal occurs naturally in its pure, free form (native silver), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite.

Most silver is produced as a by-product of copper, gold, lead, and zinc refining.

Silver metal is used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions.  Silver has the highest electrical conductivity of all metals, even higher than copper, but its greater cost has prevented it from being widely used in place of copper for electrical purposes.

Despite this, 13,540 tons were used in the electromagnets used for enriching uranium during World War II (mainly because of the wartime shortage of copper).

Silver compounds are used in photographic film. Silver halides are photosensitive and are remarkable for their ability to record a latent image that can later be developed chemically.

Dilute silver nitrate solutions and other silver compounds are used as disinfectants and micro biocides. While many medical antimicrobial uses of silver have been supplanted by antibiotics, further research into clinical potential continues.

Silver metal dissolves readily in nitric acid (HNO3) to produce silver nitrate (AgNO3), a transparent crystalline solid that is photosensitive and readily soluble in water. Silver nitrate is used as the starting point for the synthesis of many other silver compounds, as an antiseptic, and as a yellow stain for glass in stained glass.

Silver is a very ductile and malleable (slightly harder than gold). A good coinage metal with a brilliant white metallic lustre that can take a high degree of polish. The contrast between the appearance of its bright white colour in contrast with other media makes it very useful to the visual arts.

Silver has also long been used to confer high monetary value as objects (such as silver coins and investment bars) or make objects symbolic of high social or political rank.

Silver has long been valued as a precious metal, and it is used to make ornaments, jewellery, high-value tableware, utensils (hence the term silverware), and currency coins.

Silver, in the form of electrum (a gold-silver alloy), was coined to produce money in around 700 BC by the Lydians. Later, silver was refined and coined in its pure form. Many nations have used silver as the basic unit of monetary value.

Today, silver bullion has the ISO currency code XAG. The name of the pound sterling (£) reflects the fact that it originally represented the value of one troy pound of sterling silver; other historical currencies, such as the French livre, have similar etymologies.

During the 19th century, the use of silver and gold in coinage was undermined by the discovery of large deposits of silver in the Americas.

There was a fear that a sharp decrease in the value of silver and thus the currency would prevail causing most countries to switch to a gold standard by 1900.

The last currency backed by gold was the Swiss franc, which became a pure fiat currency on 1 May 2000. During this same period, silver gradually ceased to be used in circulating coins; the United States minted its last circulating silver coin in 1969.