Silver

Silver (IPA: /ˈsɪlvə/) is a chemical element with the symbol Ag (Latin: argentum). more...

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A soft white lustrous transition metal, it has the highest electrical and thermal conductivity of any metal and occurs in minerals and in free form. This metal is used in coins, jewelry, tableware, photography, and in mirrors.

Notable characteristics

Silver is a very ductile and malleable (slightly harder than gold) univalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tarnishability has prevented it from being widely used in place of copper for electrical purposes.

Pure silver also has the highest thermal conductivity, whitest color, the highest optical reflectivity (although it is a poor reflector of ultraviolet light), and the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air containing sulfur. The most common oxidation state of silver is +1 (for example, silver nitrate; AgNO₃); a few +2 (for example, silver(II) fluoride; AgF₂) and +3 compounds (for example, silver(III) persulfate; Ag₂(SO₅)₃) are also known.

Applications

The principal use of silver is as a precious metal. Its salts, especially silver nitrate and silver halides, are also widely used in photography (which is the largest single end use of silver). Some other uses for silver are as follows:

Electrical and electronic products, which need silver's superior conductivity, even when tarnished. For example, printed circuits are made using silver paints, and computer keyboards use silver electrical contacts. Silver (silver cadmium oxide) is also used in high voltage contacts because it can minimize any arcing.; Mirrors which need superior reflectivity for visible light are made with silver as the reflecting material in a process called silvering. Common mirrors are backed with aluminium.; Many high end musical instruments are made with silver, which benefit from a higher tone quality.; Silver has been coined to produce money since 700 BC by the Lydians, in the form of electrum. Later, silver was refined and coined in its pure form. The words for "silver" and "money" are the same in at least 14 languages.; The metal is chosen for its beauty in the manufacture of jewelry and silverware, which are traditionally made from the silver alloy known as Sterling silver, which is 92.5% silver and usually alloyed with copper. The name of United Kingdom monetary unit 'Pound' originally had the value of one troy pound of sterling silver.; Silver is also used in medals, denoting second place.; The malleability, non-toxicity and beauty of silver make it useful in dental alloys for fittings and fillings.; Silver's catalytic properties make it ideal for use as a catalyst in oxidation reactions; for example, the production of formaldehyde from methanol and air by means of silver screens or crystallites containing a minimum 99.95 weight-percent silver. Silver (upon some suitable support) is probably the only catalyst available today to convert ethylene to ethylene oxide (later hydrolyzed to ethylene glycol, used for making polyesters)—a very important industrial reaction.; Oxygen dissolves in silver relatively easily compared to other gases present in air. Attempts have been made to construct silver membranes of only a few monolayers thickness. Such a membrane could be used to filter pure oxygen from air.; Used to make solder and brazing alloys, electrical contacts, and high capacity silver-zinc and silver-cadmium batteries.; Silver sulfide, also known as Silver Whiskers, is formed when silver electrical contacts are used in an atmosphere rich in hydrogen sulfide.; Silver fulminate is a powerful explosive.; Silver chloride can be made transparent and is used as a cement for glass.; Silver chloride is also a widely used electrode for pH testing and potentiometric measurement.; Silver iodide has been used in attempts to seed clouds to produce rain.; Silver oxide is used as a positive electrode (cathode) in watch batteries.; Colloidal silver is a possible antibacterial / antibiotic treatment espoused in alternative medicine, also notorious for causing argyria.; Silver nitrate (liquid) was a standard of care but was largely replaced by silver sulfadiazine cream (SSD Cream) which was generally the "standard of care" for the antibacterial/antibiotic treatment of serious burns until the late 1990's. Now, other options such as silver coated dressings (activated silver dressings) are used in addition to SSD cream, and may present advantages such as pain reduction and capacity for treatment at home.; Silver is often used in modern horror fiction as a weapon against certain supernatural entities, especially werewolves, who are sometimes described as being burned by silver.;

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