silver

(sĭl'vər)

1. (Symbol Ag) A lustrous white, ductile, malleable metallic element, occurring both uncombined and in ores such as argentite, having the highest thermal and electrical conductivity of the metals. It is highly valued for jewelry, tableware, and other ornamental use and is widely used in coinage, photography, dental and soldering alloys, electrical contacts, and printed circuits. Atomic number 47; atomic weight 107.87; melting point 960.8°C; boiling point 2,212°C; specific gravity 10.50; valence 1, 2.
2. This metallic element as a commodity or medium of exchange.
3. Coins made of this metallic element.
4. A medal made of silver awarded to one placing second in a competition, as in the Olympics.
5. 1. Domestic articles, such as tableware, made of or plated with silver.
   2. Tableware, especially eating and serving utensils, made of steel or another metal.
6. A lustrous medium gray.
7. A silver salt, especially silver nitrate, used to sensitize paper.

1. Made of or containing silver: a silver bowl; silver ore.
2. Resembling silver, especially in having a lustrous shine; silvery.
3. Of a lustrous medium gray: silver hair.
4. Having a soft, clear, resonant sound.
5. Eloquent; persuasive: a silver voice.
6. Favoring the adoption of silver as a standard of currency: the silver plank of the 1896 Democratic platform.
7. Of or constituting a 25th anniversary.

1. To cover, plate, or adorn with silver or a similar lustrous substance.
2. To give a silver color to.
3. To coat (photographic paper) with a film of silver nitrate or other silver salt.

[Middle English, from Old English siolfor, seolfor, probably ultimately from Akkadian ṣarpu, refined silver, verbal adj. of ṣarāpu, to smelt, refine.]

View more Science videos

(click to enlarge)
Dendritic (branching) silver from Ontario (credit: Courtesy of Joseph and Helen Guetterman Collection; photograph, John H. Gerard)

Metallic chemical element, one of the transition elements, chemical symbol Ag, atomic number 47. It is a white, lustrous precious metal, valued for its beauty. It is also valued for its electrical conductivity, which is the highest of any metal. Between copper and gold in their common group of the periodic table, it is intermediate between them in many properties. Widely distributed in nature in small amounts, as the native metal and in ores, it is usually recovered as a by-product of copper and lead production. Its use in bullion and coins was overtaken in the 1960s by demand for industrial purposes, especially photography. It is also used in printed electrical circuits, electronic conductors, and contacts. It is the catalyst for converting ethylene to ethylene oxide, the precursor of many organic chemicals. Its use in alloys in sterling (92.5% silver, 7.5% copper) and plated silverware, ornaments, and jewelry remains important; yellow gold used in jewelry is typically 25% silver, and gold dental alloys are about 10% silver. Silver dental fillings are an amalgam of silver and mercury. Silver in compounds, the most important of which is silver nitrate, has valence 1. Its chloride, bromide, and iodide are used in photography and its iodide in cloud seeding.

For more information on silver, visit Britannica.com.

Background

Silver was one of the earliest metals known to humans, and it has been considered a precious metal since ancient times. Silver has been used as a form of currency by more people throughout history than any other metal, even gold. Although it is usually found in ores with less rare metals, such as copper, lead, and zinc, silver was apparently discovered in nugget form, called native silver, about 4000 B.C. Silver utensils and ornaments have been found in ancient tombs of Chaldea, Mesopotamia, Egypt, China, Persia, and Greece. In more recent times, the principal uses for silver were coinage and silverware.

In 1993, worldwide production of silver from mines totaled 548.2 million ounces (15.5 billion grams). During that year, Mexico was the world's largest producer of silver, with a total production of 75.7 million ounces (2.1 billion grams). The United States was the second leading producer, followed by Canada, Australia, Spain, Peru, and Russia. The vast majority of the world's silver is used in industrial applications, and the United States is the leading consumer. Other top consumers include Japan, India, and eastern European countries.

Silver mining in North America dates back to the eighteenth century. Around 1800, production began in the United States on the east coast and then moved west. The mining of silver was instrumental in the settlement of the state of Nevada. In 1994, Nevada was the largest producer of silver in the United States; Nevada mines produced 22.8 million troy ounces (709 million grams) of silver. Arizona, California, and Nevada are known for large-tonnage, low-grade silver deposits.

Physical Characteristics and Uses of Silver

Silver is the whitest metallic element. It is rare, strong, corrosion resistant, and unaffected by moisture, vegetable acids, or alkalis. Silver is also resonant, moldable, malleable, and possesses the highest thermal and electric conductivity of any substance. The chemical symbol for silver is Ag, from the Latin argentum, which means white and shining. Although silver does not react to many chemicals, it does react with sulfur, which is always present in the air, even in trace amounts. The reaction causes silver to tarnish, therefore, it must be polished periodically to retain its luster.

Silver possesses many special physical characteristics and qualities that make it useful in a variety of industries. The photography industry is the biggest user of silver compounds. Silver forms the most light-sensitive salts, or halides, which are essential to developing high-quality photography. Silver has the highest electrical conductivity per unit volume of any metal, including copper, so it is used extensively in electronics. Specialized uses include switch and relay contacts for automobile controls and accessories, automotive window heating, and in electrodes for electrocardiograms.

Silver is one of the strongest oxidants, making it an essential catalyst for the chemical process industry. It is used in the production of adhesives, dinnerware, mylar recording tape, and many other products. Silver is the most reflective of all metals, and is used to coat glass in mirrors. It is also used in x-ray vacuum tubes and as material for bearings. With the highest level of thermal conductivity among metals and resistance to combustion and sparks, silver is a valuable material for a range of other industrial processes. The most common consumer application of silver is its use in jewelry. Pure silver, which would be too soft to be durable, is mixed with 5-20% copper in an alloy known as sterling silver.

Today, a very small percentage of the world's silver is used in coinage, though silver coins were a popular form of currency until the recent past. As industrialized nations began to produce large numbers of silver coins in the twentieth century, silver became less available, and therefore more expensive. The United States Treasury, which until then had been minting 90% silver coins, changed their minting by a 1965 act of Congress. The Johnson Silver Coinage Act completely demonetized silver, and with the exception of bicentennial coins, all newly-minted United States coins are now made of an alloy of copper and nickel.

The Manufacturing
Process

Silver was first obtained in sixteenth-century Mexico by a method called the patio process. It involved mixing silver ore, salt, copper sulphide, and water. The resultant silver chloride was then picked up by adding mercury. This inefficient method was superseded by the von Patera process. In this process, ore was heated with rock salt, producing silver chloride, which was leached out with sodium hyposulfite. Today, there are several processes used to extract silver from ores.

A method called the cyanide, or heap leach, process has gained acceptance within the mining industry because it is a low-cost way of processing lower-grade silver ores. However, the ores used in this method must have certain characteristics: the silver particles must be small; the silver must react with cyanide solutions; the silver ores must be relatively free of other mineral contaminants and/or foreign substances that might interfere with the cyanidation process; and the silver must be free from sulfide minerals. The idea for cyanidation actually dates back to the eighteenth century, when Spanish miners percolated acid solutions through large heaps of copper oxide ore. The process developed into its present form during the late nineteenth century. The cyanide process is described here.

Preparing the ore

• Silver ore is crushed into pieces, usually with 1-1.5 in (2.5-3.75 cm) diameters, to make the material porous. Approximately 3-5 lb (1.4-2.3 kg) of lime per ton of silver ore is added to create an alkaline environment. The ore must be completely oxidized so the precious metal is not confined in sulfide minerals. Where fines or clays exist, the ore is agglomerated to create a uniform leach pile. This process consists of crushing the ore, adding cement, mixing, adding water or a cyanide solution, and curing in dry air for 24-48 hours.
• Broken or crushed ore is stacked on impermeable pads to eliminate the loss of the silver cyanide solution. Pad material may be asphalt, plastic, rubber sheeting, and/or clays. These pads are sloped in two directions to facilitate drainage and the collection of the solutions.

Adding the cyanide solution and curing

• A solution of water and sodium cyanide is added to the ore. Solutions are delivered to the heaps by sprinkler systems or methods of ponding, including ditches, injection, or seepage from capillaries.

Recovering the silver

• Silver is recovered from heap leach solutions in one of several ways. Most common is Merrill-Crowe precipitation, which uses fine zinc dust to precipitate the precious metal from the solution. The silver precipitate is then filtered off, melted, and made into bullion bars.
• Other methods of recovery are activated carbon absorption, where solutions are pumped through tanks or towers containing activated carbon, and the addition of a sodium sulfide solution, which forms a silver precipitate. In another method, the solution is passed through charged resin materials which attract the silver. The recovery method is generally decided based on economic factors.

Silver is rarely found alone, but mostly in ores which also contain lead, copper, gold, and other metals which may be commercially valuable. Silver emerges as a byproduct of processing these metals. To recover silver from zinc-bearing ores, the Parkes process is used. In this method, the ore is heated until it becomes molten. As the mixture of metals is allowed to cool, a crust of zinc and silver forms on the surface. The crust is removed, and the metals undergo a distillation process to remove the zinc from the silver.

To extract silver from copper-containing ores, an electrolytic refining process is used. The ore is placed in an electrolytic cell, which contains a positive electrode, or anode, and a negative electrode, or cathode, in an electrolyte solution. When electricity is passed through the solution, silver, with other metals, accumulates as a slime at the anode while copper is deposited on the cathode. The slimes are collected, then roasted, leached, and smelted to remove impurities. The metals are formed into blocks which are used as anodes in another round of electrolysis. As electricity is sent through a solution of silver nitrate, pure silver is deposited onto the cathode.

The Future

How much silver will be produced in the future depends on many factors, including the rate of production of other metals and future uses of silver. Industrial demand for silver appears to be steady overall. Because silver naturally occurs with other metals, future production is linked to the production of copper, lead, gold, and zinc.

In the future, silver will likely continue to be used for special industrial applications, as well as for consumer items, such as jewelry and silverware. In addition to these traditional uses, the value of silver will also depend on new uses for the metal. For example, using silver as a sanitizing agent is currently under development. Manufacturers have hustled in response to studies by the Atlanta-based Center for Disease Control that many viruses, including those linked to Acquired Immunodeficiency Syndrome (AIDS), will survive briefly outside an individual in fluids deposited on surfaces of plastic products, such as telephones. Matsushita Electric Industrial Co., Ltd. in Osaka, Japan, completed a project at the Research Institute for Microbial Diseases, Osaka University, to produce a surface treatment that provides long-lasting sanitization for its plastic products. Research revealed the most effective system to be a compound based on silver thiosulfate.

Currently marketed under the name Amenitop, the system consists of silica gel microspheres that contain a silver thiosulfate complex. The silica gel coating allows a gradual release of the silver compound onto the surface, which provides long-lasting sanitization. Studies suggest that Amenitop kills bacteria and viruses by destroying the cell's membranes.

Where to Learn More

Books

Coombs, Charles. Gold and Other Precious Metals. William Morrow and Company, 1981.

Robbins, Peter and Douglass Lee. Guide to Precious Metals and Their Markets. Nichols Publishing, 1979.

Smith, Jerome F. and Barbara Kelly Smith. What's Behind the New Boom In Silver and How to Maximize Your Profits. Griffin Publishing Company, 1983.

Periodicals

"A Listing of the End Users of Silver By Property." The Silver Institute, January 13, 1994, pp. 1-14.

"A Nevada Leader." News from Las Vegas (Las Vegas News Bureau), March 1995, p. 1.

"New Silver Compound To Fight Spread of Viruses." The Silver Institute Letter, December 1994-January 1995, pp. 1, 2,4.

Thorstad, Linda E. "How Heap Leaching Changed The West." World Investment News, February 1987, pp. 31, 33.

[Article by: Susan Bard Hall]

A chemical element, Ag, atomic number 47, atomic mass 107.868. It is a gray-white, lustrous metal. Chemically it is one of the heavy metals and one of the noble metals; commercially it is a precious metal. There are 25 isotopes of silver with atomic masses ranging from 102 to 117. Ordinary silver is made up of the isotopes of masses 107 (52% of natural silver) and 109 (48%). See also Periodic table.

Although silver is the most active chemically of the noble metals, it is not very active in comparison with most other elements. It does not oxidize as iron does when it rusts, but it reacts with sulfur or hydrogen sulfide to form the familiar silver tarnish. Electroplating silver with rhodium prevents this discoloration. Silver itself does not react with dilute nonoxidizing acids (hydrochloric or sulfuric acids) or strong bases (sodium hydroxide). However, oxidizing acids (nitric or concentrated sulfuric acids) dissolve it by reaction to form the unipositive silver ion, Ag⁺. The Ag⁺ ion is colorless, but a number of silver compounds are colored because of the influence of their other constituents.

Silver is almost always monovalent in its compounds, but an oxide, fluoride, and sulfide of divalent silver are known. Some coordination compounds of silver, also called silver complexes, contain divalent and trivalent silver. Although silver does not oxidize when heated, it can be oxidized chemically or electrolytically to form silver oxide or peroxide, a strong oxidizing agent. Because of this activity, silver finds considerable use as an oxidation catalyst in the production of certain organic materials.

Soluble silver salts, especially AgNO₃, have proved lethal in doses as small as 0.07 oz (2 g). Silver compounds may be slowly absorbed by the body tissues, with a resulting bluish or blackish pigmentation of the skin (argyria).

Silver is a rather rare element, ranking 63rd in order of abundance. Sometimes it occurs in nature as the free element (native silver) or alloyed with other metals. For the most part, however, silver is found in ores containing silver compounds. The principal silver ores are argentite, Ag₂S, cerargyrite or horn silver, AgCl, and several minerals in which silver sulfide is combined with sulfides of other metals; stephanite, 5Ag₂SÖSb₂S₅; polybasite, 9(Cu₂S, Ag₂S)Ö(Sb₂S₃, As₂S₃); proustite, 3Ag₂SÖAs₂S₃; and pyragyrite, 3Ag₂SÖSb₂S₃. About three-fourths of the silver produced is a by-product of the extraction of other metals, copper and lead in particular.

Pure silver is a white, moderately soft metal (2.5–3 on Mohs hardness scale), somewhat harder than gold. When polished, it has a brilliant luster and reflects 95% of the light falling on it. Silver is second to gold in malleability and ductility. Its density is 10.5 times that of water. The quality of silver, its fineness, is expressed as parts of pure silver per 1000 parts of total metal. Commercial silver is usually 999 fine. Silver is available commercially as sterling silver (7.5% copper) and in ingots, plate, moss, sheets, wire, castings, tubes, and powder.

Silver, with the highest thermal and electrical conductivities of all the metals, is used for electrical and electronic contact points and sometimes for special wiring. Silver has well-known uses in jewelry and silverware. Silver compounds are used in many photographic materials. In most of its uses, silver is alloyed with one or more other metals. Alloys in which silver is an ingredient include dental amalgam and metals for engine pistons and bearings.

Not of interest in foods apart from its use in covering non-pareils, the silver beads used to decorate confectionery. Present in traces in all plant and animal tissues but not known to be a dietary essential, and has no known function, nor is enough ever absorbed to cause toxicity. See also oligodynamic.

Idioms beginning with silver:
silver lining

In addition to the idiom beginning with silver, also see born with a silver spoon; cross someone's palm with silver; hand to on a silver platter.

Silver coins are mentioned in many different contexts. It is not clear how much intrinsic power ascribed to the metal itself—some, no doubt, since there is evidence that in Suffolk around 1850 people with fits would beg twelve small silver items such as broken spoons or buckles, to melt into a curative ring, and in some of the stories where a hare (really a witch) is shot with a silver bullet, this is said to be made from a button. However, silver objects were not regularly thought powerful in the way that domestic iron objects were.

A silver sixpence is frequently mentioned: as a gift to a new baby; as a gift left by fairies for diligent servant girls, or for children shedding a tooth; as a lucky charm, especially in a bride's shoe; as a countercharm against witchcraft when churning milk. A particular healing power was ascribed to rings made from a silver coin which had been put into the collection in church (so-called ‘sacrament money’), usually a shilling or half a crown; to get it, the sufferer had to beg a penny apiece from twelve (or 30) different people, usually with the further condition that they must be unmarried, and of the sex opposite to the sufferer's, and then exchange them for the ‘sacrament money’. They were supposed to cure fits. Sometimes, it was thought sufficient to beg five, seven, or nine sixpenny or threepenny pieces from persons of the opposite sex, and make the ring of them.

Bibliography
The full bibliography list is available here.

• Opie and Tatem, 1989: 327-8, 357-8

An element commonly used in jewelry, coins, electronics, and photography. Silver has the highest electrical conductivity of any metal.

Investopedia Says:
Silver is considered to be a precious metal.

Related Links:
All that glitters isn't gold. Find out how to get started on your treasure hunt. A Beginner's Guide To Precious Metals
If you are a hedger or a speculator, this market offers a world of profit-making opportunities. Trading Gold And Silver Futures Contracts
Find out how the largest speculative attempt to corner the market went awry. Silver Thursday: How Two Wealthy Traders Cornered The Market
This method may seem arcane, but many well-established strategies rely on it. Trading The Gold-Silver Ratio
Trading the commodities can mean extra expenses. These commodity-based ETFs give you the flexibility of trading like stocks. Options On Gold And Silver ETFs

Environment

In ore veins.

In cubic or octahedral crystals, but either is uncommon; more often it forms long contorted wires. However, the cubic Kongsberg (Norway) crystals--among the best--may be pseudomorphs formed from the sulfide mineral argentite (acanthite at room temperature).

Fresh surface bright white, usually blackened by tarnish. Luster metallic; hardness 2Ɖ-3; specific gravity 10.0-11.0. Very malleable and ductile.

Silver, usually fairly pure.

Pure silver fuses readily on charcoal to a white button. Impurities tend to make melting more difficult. Dissolves in nitric acid, producing a white curdy precipitate on the addition of hydrochloric acid.

No other white malleable metal, soluble in acid, is likely to be encountered in its native state. Lead is softer and grayer; platinum is harder and insoluble; the silvery sulfides are brittle.

In Mexico and Norway in veins with calcite and silver sulfides; often in wires and in good crystals. In n. Canada (Great Bear Lake) and Czechoslovakia with uranium ores (pitchblende). In Michigan in pure masses appended to copper sheets and forming aggregates known as "half-breeds." Native silver is not an important source of silver; lead and silver minerals with which it is commonly associated, as at Cobalt, Ontario, and in Idaho, are richer in silver. Lead ores that formed at higher temperatures than the sedimentary deposits of the Mississippi Valley are more likely to contain significant percentages of silver.

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

Silver is a precious metal associated with the emotions, the feminine quality, and the moon.

1. a chemical element, atomic number 47, atomic weight 107.870, symbol Ag. It is used in medicine for its caustic, astringent and antiseptic effects. Experimental poisoning with silver salts causes myopathy.
2. a coat color in dogs, foxes.

• s. amalgam — see amalgam.
• s. collie syndrome — see canine cyclic hematopoiesis.
• s. grass — aristida contorta.
• s. halide — any of the silver salts with halogens including bromine, chlorine, iodine used in photographic emulsion.
• s. iodide — soluble silver salt used in cloud seeding but presents no toxicological risk to local grazing cattle.
• s.-leaf ironbark — eucalyptus melanophloia.
• s.-leafed nightshade — solanum elaeagnifolium.
• s. nitrate — colorless or white crystals, used as a caustic and local anti-infective.
• s. nitrate (toughened) — a mixture of silver nitrate with hydrochloric acid, sodium chloride or potassium nitrate, occurring as white crystalline masses molded into pencils or cones, called caustic pencils; a convenient means of applying silver nitrate locally. Called also lunar caustic.
• s. protein — silver made colloidal by the presence of, or combination with, protein; an active germicide with a local irritant and astringent effect.
• s. stain — a method of demonstrating flagella on bacteria, or for visualizing very thin bacteria, such as leptospires.
• s. sulfadiazine — the silver salt of sulfadiazine, having bactericidal activity against many gram-positive and gram-negative organisms, as well as being effective against yeasts; used as a topical anti-infective for the prevention and treatment of wound sepsis in patients with second and third degree burns.
• s. weed — see potentilla anserina.

A whitish precious metal occurring mainly as a sulfide. Its atomic number is 47, and its atomic weight is 107.88. It is quite soft and is usually alloyed with small amounts of copper to increase its durability. It is used extensively in photography, radiography, and dentistry.

• Pure metals
• Elements - silver: Ag; atomic number 47, atomicweight 108
• Money, Currency, and Denominations - silver: white precious metal used in manufacture of coins and as monetary standard
• White

This article is about the chemical element. For the color, see Silver (color). For other uses, see Silver (disambiguation).

palladium ← silver → cadmium Cu ↑ Ag ↓ Au 47Ag Periodic table
Appearance
lustrous white metal Electrolytically refined silver
General properties
Name, symbol, number	silver, Ag, 47
Pronunciation	/ˈsɪlvər/
Element category	transition metal
Group, period, block	11, 5, d
Standard atomic weight	107.8682
Electron configuration	[Kr] 4d10 5s1
Electrons per shell	2, 8, 18, 18, 1 (Image)
Physical properties
Phase	solid
Density (near r.t.)	10.49 g·cm−3
Liquid density at m.p.	9.320 g·cm−3
Melting point	1234.93 K, 961.78 °C, 1763.2 °F
Boiling point	2435 K, 2162 °C, 3924 °F
Heat of fusion	11.28 kJ·mol−1
Heat of vaporization	250.58 kJ·mol−1
Molar heat capacity	25.350 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1283 1413 1575 1782 2055 2433
Atomic properties
Oxidation states	1, 2, 3 (amphoteric oxide)
Electronegativity	1.93 (Pauling scale)
Ionization energies	1st: 731.0 kJ·mol−1
	2nd: 2070 kJ·mol−1
	3rd: 3361 kJ·mol−1
Atomic radius	144 pm
Covalent radius	145±5 pm
Van der Waals radius	172 pm
Miscellanea
Crystal structure	face-centered cubic
Magnetic ordering	diamagnetic[1]
Electrical resistivity	(20 °C) 15.87 nΩ·m
Thermal conductivity	429 W·m−1·K−1
Thermal diffusivity	(300 K) 174 mm²/s
Thermal expansion	(25 °C) 18.9 µm·m−1·K−1
Young's modulus	83 GPa
Shear modulus	30 GPa
Bulk modulus	100 GPa
Poisson ratio	0.37
Mohs hardness	2.5
Vickers hardness	251 MPa
Brinell hardness	206 MPa
CAS registry number	7440-22-4
Most stable isotopes
Main article: Isotopes of silver
iso NA half-life DM DE (MeV) DP 105Ag syn 41.2 d ε - 105Pd γ 0.344, 0.280, 0.644, 0.443 - 106mAg syn 8.28 d ε - 106Pd γ 0.511, 0.717, 1.045, 0.450 - 107Ag 51.839% 107Ag is stable with 60 neutrons 108mAg syn 418 y ε - 108Pd IT 0.109 108Ag γ 0.433, 0.614, 0.722 - 109Ag 48.161% 109Ag is stable with 62 neutrons 111Ag syn 7.45 d β− 1.036, 0.694 111Cd γ 0.342 -
v d e · r

Silver ( /ˈsɪlvər/ sil-vər) 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. A soft, white, lustrous transition metal, it 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 byproduct of copper, gold, lead, and zinc refining.

Silver has long been valued as a precious metal, and it is used to make ornaments, jewelry, high-value tableware, utensils (hence the term silverware), and currency coins. Today, silver metal is also used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film, and dilute silver nitrate solutions and other silver compounds are used as disinfectants and microbiocides. While many medical antimicrobial uses of silver have been supplanted by antibiotics, further research into clinical potential continues.

Contents 1 Characteristics 2 Isotopes 3 Compounds 4 Applications 4.1 Currency 4.2 Jewelry and silverware 4.3 Dentistry 4.4 Photography and electronics 4.5 Mirrors and optics 4.6 Other industrial and commercial applications 4.7 Medical 4.8 Clothing 5 History 6 World War II 7 Occurrence and extraction 8 Price 9 Human exposure and consumption 9.1 Monitoring exposure 9.2 Use in food 10 See also 11 References 12 External links

Characteristics

Silver 1000 oz t (~31 kg) bullion bar

Silver is a very ductile, malleable (slightly harder than gold), monovalent 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 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).^[2][3][4] An exception to this is in radio-frequency engineering, particularly at VHF and higher frequencies, where silver plating to improve electrical conductivity of parts, including wires, is widely employed. Another notable exception is in high-end audio cables, where manufacturers claim that scaling copper conductors by 6% achieves slightly better results.^{[citation needed]}

Among metals, pure silver has the highest thermal conductivity (the nonmetal diamond and superfluid helium II are higher) and one of the highest optical reflectivities.^[5] (Aluminium slightly outdoes silver in parts of the visible spectrum, and silver is a poor reflector of ultraviolet light). Silver also has the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for their ability to record a latent image that can later be developed chemically. Silver is stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulfide, the latter forming a black layer of silver sulfide which can be cleaned off with dilute hydrochloric acid.^[6] The most common oxidation state of silver is +1 (for example, silver nitrate: AgNO₃); in addition, +2 compounds (for example, silver(II) fluoride: AgF₂) and the less common +3 compounds (for example, potassium tetrafluoroargentate: K[AgF₄] ) are known.

Isotopes

Main article: Isotopes of silver

Naturally occurring silver is composed of two stable isotopes, ¹⁰⁷Ag and ¹⁰⁹Ag, with ¹⁰⁷Ag being the most abundant (51.839% natural abundance). Silver's isotopes are almost equal in abundance, something which is rare in the periodic table. Silver's atomic weight is 107.8682(2) g/mol.^[7][8] Twenty-eight radioisotopes have been characterized, the most stable being ¹⁰⁵Ag with a half-life of 41.29 days, ¹¹¹Ag with a half-life of 7.45 days, and ¹¹²Ag with a half-life of 3.13 hours. This element has numerous meta states, the most stable being ^108mAg (t_1/2 = 418 years), ^110mAg (t_1/2 = 249.79 days) and ^106mAg (t_1/2 = 8.28 days). All of the remaining radioactive isotopes have half-lives that are less than an hour, and the majority of these have half-lives that are less than three minutes.

Isotopes of silver range in relative atomic mass from 93.943 (⁹⁴Ag) to 126.936 (¹²⁷Ag);^[9] the primary decay mode before the most abundant stable isotope, ¹⁰⁷Ag, is electron capture and the primary mode after is beta decay. The primary decay products before ¹⁰⁷Ag are palladium (element 46) isotopes, and the primary products after are cadmium (element 48) isotopes.

The palladium isotope ¹⁰⁷Pd decays by beta emission to ¹⁰⁷Ag with a half-life of 6.5 million years. Iron meteorites are the only objects with a high-enough palladium-to-silver ratio to yield measurable variations in ¹⁰⁷Ag abundance. Radiogenic ¹⁰⁷Ag was first discovered in the Santa Clara meteorite in 1978.^[10] The discoverers suggest the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. ¹⁰⁷Pd–¹⁰⁷Ag correlations observed in bodies that have clearly been melted since the accretion of the solar system must reflect the presence of unstable nuclides in the early solar system.^[11]

Compounds

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 metal does not react with sulfuric acid, which is used in jewelry-making to clean and remove copper oxide firescale from silver articles after silver soldering or annealing. However, silver reacts readily with sulfur or hydrogen sulfide H₂S to produce silver sulfide, a dark-colored compound familiar as the tarnish on silver coins and other objects. Silver sulfide also forms silver whiskers when silver electrical contacts are used in an atmosphere rich in hydrogen sulfide.

4 Ag + O₂ + 2 H₂S → 2 Ag₂S + 2 H₂O

Cessna 210 equipped with a silver iodide generator for cloud seeding

Silver chloride (AgCl) is precipitated from solutions of silver nitrate in the presence of chloride ions, and the other silver halides used in the manufacture of photographic emulsions are made in the same way, using bromide or iodide salts. Silver chloride is used in glass electrodes for pH testing and potentiometric measurement, and as a transparent cement for glass. Silver iodide has been used in attempts to seed clouds to produce rain.^[6] Silver halides are highly insoluble in aqueous solutions and are used in gravimetric analytical methods.

Silver oxide (Ag₂O), produced when silver nitrate solutions are treated with a base, is used as a positive electrode (anode) in watch batteries. Silver carbonate (Ag₂CO₃) is precipitated when silver nitrate is treated with sodium carbonate (Na₂CO₃).^[12]

2 AgNO₃ + 2 OH^- → Ag₂O + H₂O + 2 NO₃^-

2 AgNO₃ + Na₂CO₃ → Ag₂CO₃ + 2 NaNO₃

Silver fulminate (AgONC), a powerful, touch-sensitive explosive used in percussion caps, is made by reaction of silver metal with nitric acid in the presence of ethanol (C₂H₅OH). Another dangerously explosive silver compound is silver azide (AgN₃), formed by reaction of silver nitrate with sodium azide (NaN₃).^[13]

Latent images formed in silver halide crystals are developed by treatment with alkaline solutions of reducing agents such as hydroquinone, metol (4-(methylamino)phenol sulfate) or ascorbate, which reduce the exposed halide to silver metal. Alkaline solutions of silver nitrate can be reduced to silver metal by reducing sugars such as glucose, and this reaction is used to silver glass mirrors and the interior of glass Christmas ornaments. Silver halides are soluble in solutions of sodium thiosulfate (Na₂S₂O₃) which is used as a photographic fixer, to remove excess silver halide from photographic emulsions after image development.^[12]

Silver metal is attacked by strong oxidizers such as potassium permanganate (KMnO₄) and potassium dichromate (K₂Cr₂O₇), and in the presence of potassium bromide (KBr), these compounds are used in photography to bleach silver images, converting them to silver halides that can either be fixed with thiosulfate or redeveloped to intensify the original image. Silver forms cyanide complexes (silver cyanide) that are soluble in water in the presence of an excess of cyanide ions. Silver cyanide solutions are used in electroplating of silver.^[12]

Applications

Many well known uses of silver involve its precious metal properties, including currency, decorative items and mirrors. The contrast between the appearance of its bright white color to other media makes it very useful to the visual arts. It 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.

Currency

Main articles: Silver coin and Silver standard

Silver, in the form of electrum (a gold-silver alloy), was coined to produce money around 700 BC by the Lydians. Later, silver was refined and coined in its pure form. Many nations used silver as the basic unit of monetary value. In the modern world, silver bullion has the ISO currency code XAG. The name of the pound sterling (£) reflects the fact 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 bimetallism that prevailed in most countries was undermined by the discovery of large deposits of silver in the Americas; fearing a sharp decrease in the value of silver and thus the currency, most states switched to a gold standard by 1900. In the Spanish language, Plata means both silver and money.

The 20th century saw a gradual movement to fiat currency, with most of the world monetary system losing its link to precious metals after Richard Nixon took the United States dollar off the gold standard in 1971; 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.

Jewelry and silverware

Silver plate with goddess Minerva from the Hildesheim Treasure, 1st century BC

Royal Military College of Canada truth duty valour Collar pin (1920-53) in Silver (3 lugs)

Main articles: jewelry and silversmith

Jewelry and silverware are traditionally made from sterling silver (standard silver), an alloy of 92.5% silver with 7.5% copper. In the US, only an alloy consisting of at least 90.0% fine silver can be marketed as "silver" (thus frequently stamped 900). Sterling silver (stamped 925) is harder than pure silver, and has a lower melting point (893 °C) than either pure silver or pure copper.^[6] Britannia silver is an alternative, hallmark-quality standard containing 95.8% silver, often used to make silver tableware and wrought plate. With the addition of germanium, the patented modified alloy Argentium Sterling silver is formed, with improved properties, including resistance to firescale.

Sterling silver jewelry is often plated with a thin coat of .999 fine silver to give the item a shiny finish. This process is called "flashing". Silver jewelry can also be plated with rhodium (for a bright, shiny look) or gold.

Silver is a constituent of almost all colored carat gold alloys and carat gold solders, giving the alloys paler color and greater hardness.^[14] White 9 carat gold contains 62.5% silver and 37.5% gold, while 22 carat gold contains up to 91.7 gold and 8.4% silver or copper or a mixture of both. The more copper added, the more "orange" the gold becomes. Rose Gold (stamped 375 or 9K, can be stamped 9c) was very popular in the UK in the late 19th century.^[14]

Historically, the training and guild organization of goldsmiths included silversmiths as well, and the two crafts remain largely overlapping. Unlike blacksmiths, silversmiths do not shape the metal while it is red-hot, but instead, work it at room temperature with gentle and carefully-placed hammer blows. The essence of silversmithing is to take a flat piece of metal and to transform it into a useful object using different hammers, stakes and other simple tools.^[15]

While silversmiths specialize in, and principally work, silver, they also work with other metals, such as gold, copper, steel, and brass. They make jewelry, silverware, armor, vases, and other artistic items. Because silver is such a malleable metal, silversmiths have a large range of choices with how they prefer to work the metal. Historically, silversmiths are mostly referred to as goldsmiths, which was usually the same guild. In the western Canadian silversmith tradition, guilds do not exist; however, mentoring through colleagues becomes a method of professional learning within a community of craftspeople.^[16]

Silver is much cheaper than gold, though still valuable, and so is very popular with jewelers who are just starting out and cannot afford to make pieces in gold, or as a practicing material for goldsmith apprentices. Silver has also become very fashionable, and is used frequently in more artistic jewelry pieces.

Traditionally, silversmiths mostly made "silverware" (cutlery, table flatware, bowls, candlesticks and such). Only in more recent times has silversmithing become mainly work in jewelry, as much less solid silver tableware is now handmade.

Dentistry

Silver can be alloyed with mercury, tin and other metals at room temperature to make amalgams that are widely used for dental fillings. To make dental amalgam, a mixture of powdered silver and other metals is mixed with mercury to make a stiff paste that can be adapted to the shape of a cavity. The dental amalgam achieves initial hardness within minutes but sets hard in a few hours.

Photography and electronics

Photography used 30.98% of the silver consumed in 1998 in the form of silver nitrate and silver halides. In 2001, 23.47% was used for photography, while 20.03% was used in jewelry, 38.51% for industrial uses, and only 3.5% for coins and medals. The use of silver in photography has rapidly declined, due to the lower demand for consumer color film from the advent of digital technology; since 2007, of the 894.5 million ounces of silver in supply, just 128.3 million ounces (14.3%) were consumed by the photographic sector, and the total amount of silver consumed in 2007 by the photographic sector compared to 1998 is just 50%.^[17]

Some electrical and electronic products use silver for its superior conductivity, even when tarnished. The primary example of this is in high quality RF connectors. The increase in conductivity is also taken advantage of in RF engineering at VHF and higher frequencies, where conductors often cannot be scaled by 6%, due to tuning requirements, e.g.cavity filters. As an additional example, printed circuits and RFID antennas can be made using silver paints,^[6][18] and computer keyboards use silver electrical contacts. Silver cadmium oxide is used in high voltage contacts because it can withstand arcing.

Some manufacturers produce audio connector cables, speaker wires, and power cables using silver conductors, which have a 6% higher conductivity than ordinary copper ones of identical dimensions, but cost very much more. Though debatable, many hi-fi enthusiasts believe silver wires improve sound quality.^{[citation needed]}

Small devices, such as hearing aids and watches, commonly use silver oxide batteries due to their long life and high energy to weight ratio. Another usage is high-capacity silver-zinc and silver-cadmium batteries.

Mirrors and optics

Mirrors which need superior reflectivity for visible light are made with silver as the reflecting material in a process called silvering, though common mirrors are backed with aluminium. Using a process called sputtering, silver (and sometimes gold) can be applied to glass at various thicknesses, allowing different amounts of light to penetrate. Silver is usually reserved for coatings of specialized optics, and the silvering most often seen in architectural glass and tinted windows on vehicles is produced by sputtered aluminium, which is cheaper and less susceptible to tarnishing and corrosion.^[19] Silver is the reflective coating of choice for solar reflectors.^[20]

Other industrial and commercial applications

This Yanagisawa A9932J alto saxophone has a solid silver bell and neck with solid phosphor bronze body. The bell, neck and key-cups are extensively engraved. It was manufactured in 2008.

Silver and silver alloys are used in the construction of high quality musical wind instruments of many types.^[21] Flutes, in particular, are commonly constructed of silver alloy or silver plated, both for appearance and for the frictional surface properties of silver.^[22]

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)— an important industrial reaction. It is also used in the Oddy test to detect reduced sulfur compounds and carbonyl sulfides.

Because silver readily absorbs free neutrons, it is commonly used to make control rods to regulate the fission chain reaction in pressurized water nuclear reactors, generally in the form of an alloy containing 80% silver, 15% indium, and 5% cadmium.

Silver is used to make solder and brazing alloys, and as a thin layer on bearing surfaces can provide a significant increase in galling resistance and reduce wear under heavy load, particularly against steel.

Medical

Main article: Medical uses of silver

Silver ions and silver compounds show a toxic effect on some bacteria, viruses, algae and fungi, typical for heavy metals like lead or mercury, but without the high toxicity to humans normally associated with these other metals. Its germicidal effects kill many microbial organisms in vitro, but testing and standardization of silver products is difficult.^[23]

Hippocrates, the "father of medicine",^[24] wrote that silver had beneficial healing and antidisease properties, and the Phoenicians stored water, wine, and vinegar in silver bottles to prevent spoiling. In the early 20th century, people^[where?] would put silver coins in milk bottles to prolong the milk's freshness.^[25] Its germicidal effects increased its value in utensils and as jewellery. The exact process of silver's germicidal effect is still not entirely understood, although theories exist. One of these is the oligodynamic effect, which explains the effect on microorganisms, but would not explain antiviral effects.

Silver is widely used in topical gels and impregnated into bandages because of its wide-spectrum antimicrobial activity. The antimicrobial properties of silver stem from the chemical properties of its ionized form, Ag⁺. This ion forms strong molecular bonds with other substances used by bacteria to respire, such as molecules containing sulfur, nitrogen, and oxygen.^[26] When the Ag⁺ ion forms a complex with these molecules, they are rendered unusable by the bacteria, depriving them of necessary compounds and eventually leading to their death.

Silver compounds were used to prevent infection in World War I before the advent of antibiotics. Silver nitrate solution use continued, then was largely replaced by silver sulfadiazine cream (SSD cream),^[27] which generally became the "standard of care" for the antibacterial and antibiotic treatment of serious burns until the late 1990s.^[28] Now, other options, such as silver-coated dressings (activated silver dressings), are used in addition to SSD cream. However, the evidence for the effectiveness of such silver-treated dressings is mixed, and although the evidence is promising, it is marred by the poor quality of the trials used to assess these products. Consequently, a systematic review by the Cochrane Collaboration (published in 2008) found insufficient evidence to recommend the use of silver-treated dressings to treat infected wounds.^[29]

There has been renewed interest in silver as a broad-spectrum antimicrobial agent. One application has silver being used with alginate, a naturally occurring biopolymer derived from seaweed, in a range of products designed to prevent infections as part of wound management procedures, particularly applicable to burn victims.^[30] In 2007, a company introduced a glass product they claimed had antibacterial properties by coating the glass with a thin layer of silver.^[31] In addition, in 2007 the U.S. Food and Drug Administration (FDA) approved an endotracheal breathing tube with a fine coat of silver for use in mechanical ventilation, after studies found it reduced the risk of ventilator-associated pneumonia.^[32]

Another example uses the known enhanced antibacterial action of silver by applying an electric field. In 2009, the antibacterial action of silver electrodes was found to be greatly improved if the electrodes were covered with silver nanorods.^[33] The University of Missouri has found silver nanoparticles threaten benign bacteria which extract ammonia from sewage treatment systems. A serious concern is the eventual spread of the toxin into rivers, streams, lakes and ultimately the oceans.^[34] A note of caution is sounded by Martin A. Philbert, professor of toxicology at the University of Michigan, Ann Arbor. "In the context of environmental health, the scientific community will have to pay close attention to those physicochemical properties of engineered nanomaterials that defeat or circumvent normal cellular processes and lend themselves to indiscriminate penetration of biological barriers, tissues, and cellular systems." ^[35]

Silver is commonly used in catheters. Silver alloy catheters are more effective than standard catheters for reducing bacteriuria in adults having short term catheterisation in hospitals. This meta-analysis clarifies discrepant results among trials of silver-coated urinary catheters by revealing silver alloy catheters are significantly more effective in preventing urinary tract infections than are silver oxide catheters. Though silver alloy urinary catheters cost about $6 more than standard urinary catheters, they may be worth the extra cost, since catheter-related infection is a common cause of nosocomial infection and bacteremia.^[36]

Various silver compounds, devices to make homeopathic solutions and colloidal silver suspensions are sold as remedies for numerous conditions. Although most colloidal silver preparations are harmless, there are cases where excessive consumption led to argyria over a period of months or years.^[37] High consumption doses of colloidal silver can result in coma, pleural edema, and hemolysis.^[38]

Clothing

Silver inhibits the growth of bacteria and fungi on clothing, such as socks, so is added to reduce odors and the risk of bacterial and fungal infection. It is incorporated into clothing or shoes either by integrating silver nanoparticles into the polymer from which yarns are made or by coating yarns with silver.^[39][40] The loss of silver during washing varies between textile technologies, and the resultant effect on the environment is not yet fully known.^[41][42]

History

The crescent moon has been used since ancient times to represent silver.

Silver has been used for thousands of years for ornaments and utensils, for trade, and as the basis for many monetary systems. Its value as a precious metal was long considered second only to gold. The word "silver" appears in Anglo-Saxon in various spellings such as seolfor and siolfor. A similar form is seen throughout the Germanic languages (compare Old High German silabar and silbir). The chemical symbol Ag is from the Latin for "silver", argentum (compare Greek άργυρος, árgyros), from the Indo-European root *arg- meaning "white" or "shining". Silver has been known since ancient times. Mentioned in the book of Genesis, slag heaps found in Asia Minor and on the islands of the Aegean Sea indicate silver was being separated from lead as early as the 4th millennium BC using surface mining.^[6]

The stability of the Roman currency relied to a high degree on the supply of silver bullion, which Roman miners produced on a scale unparalleled before the discovery of the New World.^[43][44] Reaching a peak production of 200 t per year, an estimated silver stock of 10,000 t circulated in the Roman economy in the middle of the second century AD, five to ten times larger than the combined amount of silver available to medieval Europe and the Caliphate around 800 AD.^[43][44]

Recorded use of silver to prevent infection dates to ancient Greece and Rome; it was rediscovered in the Middle Ages, when it was used for several purposes, such as to disinfect water and food during storage, and also for the treatment of burns and wounds as wound dressing. In the 19th century, sailors on long ocean voyages would put silver coins in barrels of water and wine to keep the liquid potable. Pioneers in America used the same idea as they made their journey from coast to coast. Silver solutions were approved in the 1920s by the US Food and Drug Administration for use as antibacterial agents.

In the Gospels, Jesus' disciple Judas Iscariot is infamous for having taken a bribe of thirty coins of silver from religious leaders in Jerusalem to turn Jesus Christ over to the Romans.

In certain circumstances, Islam permits Muslim men to wear silver jewelry. Muhammad himself wore a silver signet ring.^{[citation needed][45]}

World War II

During World War II, the short supply of copper led to the substitution of silver in many industrial applications. The United States government loaned out silver from its massive reserve located in the West Point vaults to a wide range of industrial users. One very important use was for bus bars for new aluminum plants needed to make aircraft. During the war many electrical connectors and switches were silver plated. Another use was aircraft master rod bearings and other types of bearings. Since silver can replace tin in solder at a lower volume, a large amount of tin was freed up for other uses by substituting government silver. Silver was also used as the reflector in searchlights and other types of lights. One high-tech use of silver was for conductors at Oak Ridge National Laboratory used in calutrons to isolate uranium as part of the Manhattan project. (After the war ended the silver was returned to the vaults.)^[46] Silver was used in nickels during the war to save that metal for use in steel alloys.

Occurrence and extraction

Main article: Silver mining

Native silver

Time trend of silver production

Silver is found in native form, as an alloy with gold (electrum), and in ores containing sulfur, arsenic, antimony or chlorine. Ores include argentite (Ag₂S), chlorargyrite (AgCl) which includes horn silver, and pyrargyrite (Ag₃SbS₃). The principal sources of silver are the ores of copper, copper-nickel, lead, and lead-zinc obtained from Peru, Bolivia, Mexico, China, Australia, Chile, Poland and Serbia.^[6] Peru, Bolivia and Mexico have been mining silver since 1546, and are still major world producers. Top silver-producing mines are Cannington (Australia), Fresnillo (Mexico), San Cristobal (Bolivia), Antamina (Peru), Rudna (Poland), and Penasquito (Mexico).^[47] Top near-term mine development projects through 2015 are Pascua Lama (Chile), Navidad (Argentina), Jaunicipio (Mexico), Malku Khota (Bolivia),^[48] and Hackett River (Canada).^[47]

The metal is primarily produced through electrolytic copper refining, gold, nickel and zinc refining, and by application of the Parkes process on lead metal obtained from lead ores that contain small amounts of silver. Commercial-grade fine silver is at least 99.9% pure, and purities greater than 99.999% are available. In 2010, Peru was the top producer of silver (4,000 tonnes or 18% of the world's total), closely followed by Mexico (3,500 t) and China (3,000 t).^[49]

Price

Main articles: Silver as an investment and Silver standard

Silver output in 2005

Silver price history in 1960–2011

At an April 2011 price of about $49 USD per troy ounce,^[50] silver is about 1/30th the price of gold. The ratio has varied from 1/15 to 1/100 in the past 100 years.^{[citation needed]}

In 1980, the silver price rose to a peak for modern times of US$49.45 per troy ounce (ozt) due to market manipulation of Nelson Bunker Hunt and Herbert Hunt inflation adjusted to 2011 this is approximately U$D150 per troy ounce.^{[citation needed]} Some time after Silver Thursday, the price was back to $10/ozt.^[51] From 2001 to 2010, the price moved from $4.37 to $20.19 (Average London US$/oz).^[52] According to the Silver Institute, silver's recent gains have greatly stemmed from a rise in investor interest and an increase in fabrication demand.^[52] In late April 2011, silver reached an all-time high of $49.76/ozt.

In earlier times, silver has commanded much higher prices. In the early 15th century, the price of silver is estimated to have surpassed $1200 per ounce, based on 2011 dollars.^[53] The discovery of massive silver deposits in the New World during the succeeding centuries has caused the price to diminish greatly.

The price of silver is important in Judaic law. The lowest fiscal amount a Jewish court, or Beth Din, can convene to adjudicate a case over is a shova pruta (value of a Babylonian pruta coin)^{[citation needed]}. This is fixed at 1/8 of a gram of pure, unrefined silver, at market price. In a Jewish tradition, still continuing today, on the first birth-day of a first-born son, the parents pay the price of five pure-silver coins to a Kohen (priest). Today, the Israel mint fixes the coins at 117 grams of silver. The Kohen will often give those silver coins back as a gift for the child to inherit.^[54]

Human exposure and consumption

Silver plays no known natural biological role in humans, and possible health effects of silver are a disputed subject. Silver itself is not toxic, but most silver salts are, and some may be carcinogenic.^{[dubious – discuss]} Silver and compounds containing it (such as colloidal silver) can be absorbed into the circulatory system and become deposited in various body tissues, leading to argyria, which results in a blue-grayish pigmentation of the skin, eyes, and mucous membranes. Although this condition does not otherwise harm a person's health, it is disfiguring and usually permanent. Argyria is rare, and mild forms are sometimes mistaken for cyanosis.^[6]

Monitoring exposure

Overexposure to silver can occur in workers in the metallurgical industry, persons taking silver-containing dietary supplements, patients who have received silver sulfadiazine treatment and individuals who accidentally or intentionally ingest silver salts. Silver concentrations in whole blood, plasma, serum or urine may be measured to monitor for safety in exposed workers, to confirm the diagnosis in potential poisoning victims or to assist in the forensic investigation in a case of fatal overdosage.^[55]

Use in food

Silver is used in food coloring, it has the E174 designation, and is approved in the European Union. The amount of silver in the coating of dragée or as in cookie decoration is minuscule. The safety of silver for use in food is disputed. Traditional Indian dishes sometimes include the use of decorative silver foil known as vark, and in various cultures, silver dragée are used to decorate cakes, cookies, and other dessert items. The use of silver as a food additive is not approved in the United States and Australia.^{[citation needed]}.

See also

• List of silver compounds
• Silver as an investment
• Silver coin
• Silver mining
• Silverpoint drawing
• Vark – a pastry/confectionery decoration

References

1. ^ Magnetic susceptibility of the elements and inorganic compounds in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5. 
2. ^ Nichols, Kenneth D. (1987). The Road to Trinity. Morrow, New York: Morrow. p. 42. ISBN 068806910X. 
3. ^ "Eastman at Oak Ridge – Dr. Howard Young". http://www.tnengineering.net/AICHE/eastman-oakridge-young.htm. Retrieved 2009-06-06. 
4. ^ Oman, H. (1992). "Not invented here? Check your history". Aerospace and Electronic Systems Magazine 7 (1): 51–53. doi:10.1109/62.127132. 
5. ^ Edwards, H.W.; Petersen, R.P. (1936). "Reflectivity of evaporated silver films". Phys. Rev. 9: 871. 
6. ^ ^{a b c d e f g} Hammond, C. R. (2000). The Elements, in Handbook of Chemistry and Physics 81st edition. CRC press. ISBN 0849304814. 
7. ^ "Atomic Weights of the Elements 2007 (IUPAC)". http://www.chem.qmul.ac.uk/iupac/AtWt/index.html. Retrieved 2009-11-11. 
8. ^ "Atomic Weights and Isotopic Compositions for All Elements (NIST)". http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=&ascii=html&isotype=some. Retrieved 2009-11-11. 
9. ^ "Atomic Weights and Isotopic Compositions for Silver (NIST)". http://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Ag&ascii=html&isotype=all. Retrieved 2009-11-11. 
10. ^ Kelly, William R.; Wasserburg, G. J. (1978). "Evidence for the existence of ¹⁰⁷Pd in the early solar system". Geophysical Research Letters 5: 1079. Bibcode 1978GeoRL...5.1079K. doi:10.1029/GL005i012p01079. 
11. ^ Russell, Sara S.; Gounelle, Matthieu; Hutchison, Robert (2001). "Origin of Short-Lived Radionuclides". Philosophical Transactions: Mathematical, Physical and Engineering Sciences 359 (1787): 1991–2004. Bibcode 2001RSPTA.359.1991R. doi:10.1098/rsta.2001.0893. JSTOR 3066270. 
12. ^ ^{a b c} Bjelkhagen, Hans I. (1995). Silver-halide recording materials: for holography and their processing. Springer. pp. 156–166. ISBN 3540586199. 
13. ^ Meyer, Rudolf; Köhler, Josef and Homburg, Axel publisher = Wiley-VCH (2007). Explosives. p. 284. ISBN 3527316566. http://books.google.com/?id=ATiYCfo1VcEC&pg=PA284&dq=%22silver++fulminate%22. 
14. ^ ^{a b} "Gold Jewellery Alloys > Utilise Gold. Scientific, industrial and medical applications, products ,suppliers from the World Gold Council". Utilisegold.com. 2000-01-20. http://www.utilisegold.com/jewellery_technology/colours/colour_alloys/. Retrieved 2009-04-05. 
15. ^ "Chambers Search Chambers". http://www.chambersharrap.co.uk/chambers/features/chref/chref.py/main?query=Silversmith&title=21st&sourceid=Mozilla-search. Retrieved 2009-06-06. 
16. ^ McRae, Kelly. "Trade Secrets". Western Horseman Magazine. http://westernhorseman.com/index.php?option=com_content&task=view&id=861&Itemid=79. Retrieved 2009-06-06. 
17. ^ "Silver Supply & Demand". The Silver Institute. http://www.silverinstitute.org/supply_demand.php. Retrieved 2009-05-05. 
18. ^ Nikitin, Pavel V.; Lam, Sander and Rao, K. V. S. (2005). Low Cost Silver Ink RFID Tag Antennas. doi:10.1109/APS.2005.1552015. ISBN 0-7803-8883-6. http://www.ee.washington.edu/faculty/nikitin_pavel/papers/APS_2005.pdf. 
19. ^ Wilson, Ray N. (2004). Reflecting Telescope Optics: Basic design theory and its historical development. Springer. p. 422. ISBN 3540401067. http://books.google.com/?id=isH9fTnpc7YC&lpg=PA429&dq=silver%20optics&pg=PA429. 
20. ^ Jaworske, D.A. (1997). "Reflectivity of silver and silver-coated substrates from 25 °C to 800 °C (for solar collectors)". Energy Conversion Engineering Conference, 1997. IECEC-97., Proceedings of the 32nd Intersociety 1: 407. doi:10.1109/IECEC.1997.659223. ISBN 0-7803-4515-0. 
21. ^ Rossing, Thomas D. (1998). The physics of musical instruments. Springer. pp. 728–732. ISBN 0387983740. http://books.google.com/books?id=9CRSRYQlRLkC&pg=PA730. 
22. ^ Meyers, Arnold (2004). Musical instruments: history, technology, and performance of instruments of western music. Oxford University Press. p. 132. ISBN 0198165048. http://books.google.com/books?id=D_15UtgRVJsC&pg=PA132. 
23. ^ Chopra, I (2007). "The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?". The Journal of antimicrobial chemotherapy 59 (4): 587–90. doi:10.1093/jac/dkm006. PMID 17307768. 
24. ^ Magner, Lois N. (1992). "Hippocrates and the Hippocratic Tradition". A history of medicine. Marcel Dekker. pp. 66–68. ISBN 9780824786731. 
25. ^ "Antibacterial effects of silver". http://www.saltlakemetals.com/Silver_Antibacterial.htm. 
26. ^ Slawson RM, Van Dyke MI, Lee H, Trevors JT (1992). "Germanium and silver resistance, accumulation, and toxicity in microorganisms". Plasmid 27 (1): 72–9. doi:10.1016/0147-619X(92)90008-X. PMID 1741462. 
27. ^ Chang TW, Weinstein L (1975). "Prevention of herpes keratoconjunctivitis in rabbits by silver sulfadiazine". Antimicrob. Agents Chemother. 8 (6): 677–8. PMC 429446. PMID 1211919. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=429446. 
28. ^ Atiyeh BS, Costagliola M, Hayek SN, Dibo SA (2007). "Effect of silver on burn wound infection control and healing: review of the literature". Burns : journal of the International Society for Burn Injuries 33 (2): 139–48. doi:10.1016/j.burns.2006.06.010. PMID 17137719. 
29. ^ Lo SF, Hayter M, Chang CJ, Hu WY, Lee LL (2008). "A systematic review of silver-releasing dressings in the management of infected chronic wounds". Journal of clinical nursing 17 (15): 1973–85. doi:10.1111/j.1365-2702.2007.02264.x. PMID 18705778. 
30. ^ Hermans MH (2006). "Silver-containing dressings and the need for evidence". The American journal of nursing 106 (12): 60–8; quiz 68–9. doi:10.1097/00000446-200612000-00025. PMID 17133010. 
31. ^ "AGC Flat Glass Europe launches world’s first antibacterial glass". 2007-09-04. http://www.agc-flatglass.eu/AGC+Flat+Glass+Europe/English/Homepage/News/Press+room/Press-Detail-Page/page.aspx/979?pressitemid=1031. 
32. ^ "FDA Clears Silver-Coated Breathing Tube For Marketing". 2007-11-08. http://www.fda.gov/bbs/topics/NEWS/2007/NEW01741.html. Retrieved 2007-11-11. 
33. ^ Akhavan, O. and Ghaderi, E. (2009). "Enhancement of antibacterial properties of Ag nanorods by electric field" (free download pdf). Sci. Technol. Adv. Mater. 10 (1): 015003. Bibcode 2009STAdM..10a5003A. doi:10.1088/1468-6996/10/1/015003. http://www.iop.org/EJ/article/1468-6996/10/1/015003/stam9_1_015003.pdf. 
34. ^ Silver Nanoparticles May Be Killing Beneficial Bacteria In Wastewater Treatment. Sciencedaily.com (2008-04-30). Retrieved on 2011-05-02.
35. ^ Chemical & Engineering News: Latest News – Nanoneedles Pierce Cells. Pubs.acs.org (2007-01-31). Retrieved on 2011-05-02.
36. ^ Saint, Sanjay et al. (1998). "The efficacy of silver alloy-coated urinary catheters in preventing urinary tract infection: a meta-analysis". American Journal of Medicine 105 (3): 236–241. doi:10.1016/S0002-9343(98)00240-X. PMID 9753027. 
37. ^ Fung MC, Bowen DL (1996). "Silver products for medical indications: risk-benefit assessment". Journal of toxicology. Clinical toxicology 34 (1): 119–26. doi:10.3109/15563659609020246. PMID 8632503. 
38. ^ Wadhera A, Fung M (2005). "Systemic argyria associated with ingestion of colloidal silver". Dermatology online journal 11 (1): 12. PMID 15748553. http://dermatology.cdlib.org/111/case_reports/argyria/wadhera.html. 
39. ^ Lansdown, Alan B.G (2010). Silver in Healthcare: Its Antimicrobial Efficacy and Safety in Use. Royal Society of Chemistry. p. 159. ISBN 1849730067. http://books.google.com/books?id=QxtLm7MgQhYC&pg=PA159. 
40. ^ Duquesne, Sophie et al. (2007). Multifunctional barriers for flexible structure: textile, leather, and paper. p. 26. ISBN 3540719172. http://books.google.com/books?id=HEgZENiPqW8C&pg=PA26. 
41. ^ Geranio, L.; Heuberger, M.; Nowack, B. (2009). "The Behavior of Silver Nanotextiles during Washing". Environmental Science & Technology 43: 8113. doi:10.1021/es9018332. http://publicationslist.org/data/nowack/ref-72/Geranio%20%282009%29.pdf. 
42. ^ Washing nanotextiles: can nanosilver escape from clothes?, European Commission, 17 December 2009
43. ^ ^{a b} Patterson, C. C. (1972): "Silver Stocks and Losses in Ancient and Medieval Times", The Economic History Review, Vol. 25, No. 2, pp. 205–235 (216, table 2; 228, table 6)
44. ^ ^{a b} Callataÿ, François de (2005): "The Greco-Roman Economy in the Super Long-Run: Lead, Copper, and Shipwrecks", Journal of Roman Archaeology, Vol. 18, pp. 361–372 (365f.)
45. ^ . http://books.google.com/books?id=SWMaY6JxN5sC&pg=PT283. 
46. ^ Asimov, Isaac (1966). Building Blocks of the Universe. Abelard-Schuman. 
47. ^ ^{a b} CPM Group (2011). CPM Silver Yearbook. New York, NY: Euromoney Books. p. 68. ISBN 978-0-9826741-4-7. 
48. ^ "Preliminary Economic Assessment Technical Report 43-101". South American Silver Corp.. http://www.soamsilver.com/upload/Technical_Reports/Malku_Khota_PEA_Update_11_May_2011.pdf.pdf. 
49. ^ Silver Statistics and Information, USGS
50. ^ Commodity Futures Online Trading. Bloomberg. Retrieved on 2011-05-02.
51. ^ Abolafia, Mitchel Y; Kilduff, Martin (1988). "Enacting Market Crisis: The Social Construction of a Speculative Bubble". Administrative Science Quarterly 33 (2): 177–193. doi:10.2307/2393054. JSTOR 2393054. 
52. ^ ^{a b} World Silver Survey 2011. London: The Silver Institute and GFMS Limited. 2011. p. 8. ISBN 1059-6992. http://www.silverinstitute.org/publications.php. 
53. ^ Live Silver Prices, Silver Bullion Prices & 650 Years of Silver Prices. Goldinfo.net. Retrieved on 2011-05-02.
54. ^ Living Judaism: the complete guide to Jewish belief, tradition, Wayne D. Dosick - 1995 "The price was set at five shekalim (the plural of shekel, the monetary unit of the time) for each of the 273 extra firstborn (Numbers 3:47). The money was given to Aaron, the High Priest, the head of the tribe of Levi."
55. ^ Baselt, R. Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, 2008, ISBN 0962652377 pp. 1429–1431.

External links

Listen to this article (info/dl)

This audio file was created from a revision of the "Silver" article dated 2005-09-01, and does not reflect subsequent edits to the article. (Audio help)

More spoken articles

Wikimedia Commons has media related to: Silver

Look up silver in Wiktionary, the free dictionary.

• Society of American Silversmiths
• The Silver Institute A silver industry website
• A collection of silver items Samples of silver
• Transport, Fate and Effects of Silver in the Environment
• Picture in the Element collection from Heinrich Pniok
• Chemistry in its element podcast (MP3) from the Royal Society of Chemistry's Chemistry World: Silver

v d e  Periodic table
H																															He
Li	Be																									B	C	N	O	F	Ne
Na	Mg																									Al	Si	P	S	Cl	Ar
K	Ca															Sc	Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn	Ga	Ge	As	Se	Br	Kr
Rb	Sr															Y	Zr	Nb	Mo	Tc	Ru	Rh	Pd	Ag	Cd	In	Sn	Sb	Te	I	Xe
Cs	Ba	La	Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg	Tl	Pb	Bi	Po	At	Rn
Fr	Ra	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr	Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Uuq	Uup	Uuh	Uus	Uuo
Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Post-transition metals Metalloids Other nonmetals Halogens Noble gases Unknown chem. properties
Large version

v d e Silver compounds AgBF4 AgBr AgBrO3 AgCN AgCNO AgCl AgClO3 AgClO4 AgF AgF2 AgI AgMnO4 AgIO3 AgNO3 AgN3 Ag3N AgO AgPF6 Ag2CO3 Ag2C2 Ag2C2O4 Ag2CrO4 Ag2F Ag2MoO4 Ag2O Ag2S Ag2SO4 Ag2Se Ag2SeO3 Ag2Te Ag3PO4

v d e Jewellery Forms Anklet Belt buckle Belly chain Bindi Bracelet Brooch Chatelaine Collar pin Crown Cufflink Earring Lapel pin Necklace Pendant Ring Tiara Tie clip Toe ring Watch (pocket) Making People Bench jeweler Goldsmith Jewellery designer Lapidary Watchmaker Processes Casting (centrifugal, lost-wax, vacuum) Enameling Engraving Filigree Metal clay Plating Polishing Repoussé and chasing Soldering Stonesetting Wire wrapping Tools Draw plate File Hammer Mandrel Pliers Materials Precious metals Gold Palladium Platinum Rhodium Silver Precious metal alloys Britannia silver Colored gold Crown gold Electrum Platinum sterling Shakudō Shibuichi Sterling silver Tumbaga Base metals/alloys Brass Bronze Copper Mokume-gane Pewter Stainless steel Titanium Mineral gemstones Aventurine Agate Alexandrite Amethyst Aquamarine Carnelian Citrine Diamond Diopside Emerald Garnet Jade Jasper Lapis lazuli Larimar Malachite Marcasite Moonstone Obsidian Onyx Opal Peridot Quartz Ruby Sapphire Sodalite Sunstone Tanzanite Tiger's eye Topaz Tourmaline Turquoise Yogo sapphire Organic gemstones Amber Copal Coral Jet Pearl Abalone Ivory Terms Carat (mass) Carat (purity) Finding Millesimal fineness Related topics: Body piercing Fashion Gemology Metalworking Wearable art

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - sølv, sølvtøj, sølvpenge
v. tr. - forsølve, belægge
v. intr. - få sølvglans
adj. - sølvblank, sølvlignende, sølv-

idioms:

• silver birch    en art birketræ
• silver bullet    sølvkugle
• silver jubilee    sølvjubilæum
• silver medal    sølvmedalje
• silver paper    sølvpapir, folie
• silver plated    forsølvet
• silver screen    det hvide lærred
• silver tongue    veltalenhed, have ordet i sin magt
• silver wedding anniversary    sølvbryllupsdag

Nederlands (Dutch)
zilver, verzilveren

Français (French)
n. - argent, argenterie, couverts en argent, monnaie, médaille d'argent
v. tr. - argenter
v. intr. - argenter
adj. - d'argent, argenté

idioms:

• silver birch    bouleau argenté
• silver bullet    panacée
• silver jubilee    vingt-cinquième anniversaire
• silver medal    médaille d'argent
• silver paper    papier d'argent
• silver plate    métal argenté
• silver screen    le grand écran
• silver tongue    langue déliée
• silver wedding anniversary    noces d'argent

Deutsch (German)
n. - Silber
v. - versilbern, ergrauen (lassen)
adj. - silbern, Silber-

idioms:

• silver birch    (Bot.) Weißbirke
• silver bullet    magische Waffe, Zauberformel, Wunderlösung
• silver jubilee    silbernes Jubiläum
• silver medal    Silbermedaille
• silver paper    Silberpapier
• silver plate    Silberauflage, Silbergeschirr
• silver screen    Leinwand
• silver tongue    Redegewandtheit
• silver wedding anniversary    Silberhochzeit

Ελληνική (Greek)
n. - άργυρος, ασήμι, ασημικά, αργύρια
v. - επαργυρώνω, ασημοκαπνίζω
adj. - αργυρός, ασημένιος, αργυρούχος, ασημοκαπνίζω

idioms:

• silver birch    (φυτολ.) σημύδα η λευκή
• silver bullet    (καθομ.) μαγική λύση προβλήματος
• silver jubilee    25η επέτειος
• silver medal    αργυρό μετάλλιο
• silver paper    ασημόχαρτο, ευαισθητοποιημένο χαρτί
• silver plated    επάργυρος, ασημοκαπνισμένος
• silver screen    οθόνη του κινηματογράφου, (ο) κινηματογράφος
• silver tongue    γλυκύτητα λόγων
• silver wedding anniversary    25η επέτειος γάμων, αργυροί γάμοι

Italiano (Italian)
argentare, argenteo

idioms:

• silver birch    betulla bianca
• silver bullet    pallottola d'argento, treno rapido (USA)
• silver jubilee    nozze d'argento, 25o anniversario del regno
• silver medal    medaglia d'argento
• silver paper    carta argentata
• silver plate    argenteria placcata
• silver plated    placcato argento
• silver screen    il cinema
• silver tongue    eloquenza
• silver wedding    nozze d'argento

Português (Portuguese)
n. - prata (f), cor (f) de prata, baixela (f) de prata
v. - pratear, embranquecer, ficar grisalho
adj. - argênteo, prateado

idioms:

• silver birch    tipo de árvore (f)
• silver bullet    bala (f) de prata
• silver jubilee    jubileu (m) de prata
• silver medal    medalha (f) de prata
• silver paper    papel (m) prateado
• silver plated    prateado
• silver screen    tela (f) prateada para cinema
• silver tongue    eloquência (f)
• silver wedding    bodas (f pl) de prata

Русский (Russian)
серебро, серебряные монеты, серебряные изделия, серебряный, серебристый, мелодичный, покрывать серебром, амальгамировать, серебриться, седеть

idioms:

• silver birch    серебряная береза
• silver bullet    серебряная пуля
• silver jubilee    серебряный юбилей
• silver medal    серебряная медаль
• silver paper    белая папиросная бумага, фольга
• silver plated    посеребренный
• silver screen    киноэкран
• silver tongue    красноречие
• silver wedding    серебряная свадьба

Español (Spanish)
n. - plata, vajilla o cubiertos de plata, color de plata
v. tr. - platear, azogar, blanquear
v. intr. - volverse plateado
adj. - de plata, plateado, argentino

idioms:

• silver birch    abedul común
• silver bullet    varita mágica
• silver jubilee    vigésimo quinto aniversario
• silver medal    medalla de plata
• silver paper    papel de plata
• silver plate    baño de plata, vajilla de plata
• silver screen    industria del cine
• silver tongue    elocuencia
• silver wedding anniversary    bodas de plata

Svenska (Swedish)
n. - silver, silverpengar
v. - försilvra, bli försilvrad, försilvras
adj. - silver-, av silver

中文（简体）(Chinese (Simplified))
银, 银器, 银币, 镀银于, 使有银色光泽, 变成银色, 银的, 含银的, 镀银的, 银色的, 有银色光泽的

idioms:

• silver birch    白桦树
• silver bullet    银子弹
• silver jubilee    二十五周年纪念
• silver medal    银质奖章, 银牌
• silver paper    锡箔纸
• silver plated    包银的, 镀银的
• silver screen    银幕, 电影
• silver tongue    能言善辩, 口才好的
• silver wedding anniversary    银婚纪念, 结婚25周年纪念

中文（繁體）(Chinese (Traditional))
n. - 銀, 銀器, 銀幣
v. tr. - 鍍銀於, 使有銀色光澤
v. intr. - 變成銀色
adj. - 銀的, 含銀的, 鍍銀的, 銀色的, 有銀色光澤的

idioms:

• silver birch    白樺樹
• silver bullet    銀子彈
• silver jubilee    二十五周年紀念
• silver medal    銀質獎章, 銀牌
• silver paper    錫箔紙
• silver plated    包銀的, 鍍銀的
• silver screen    銀幕, 電影
• silver tongue    能言善辯, 口才好的
• silver wedding anniversary    銀婚紀念, 結婚25週年紀念

한국어 (Korean)
n. - 은(금속 원소), 은빛의 광택, 은화
v. tr. - 은을 씌우다, 백발이 되게 하다
v. intr. - 은빛이 되다, (머리가) 백발이 되다
adj. - 은의, 웅변의, (결혼 기념일 등) 25주년의

日本語 (Japanese)
n. - 銀, 銀細工品, 銀貨, 銀色
v. - 銀をかぶせる, 銀めっきする, 銀白色になる, 銀色に変わる
adj. - 銀の, 銀と化合した, 銀のような, 澄んだ

idioms:

• silver birch    シラカンバ
• silver bullet    ピストル
• silver jubilee    二十五周年祝典
• silver medal    銀メダル
• silver paper    銀器を包む薄紙, 銀紙
• silver plated    銀メッキの
• silver screen    銀幕, 映画界
• silver tongue    雄弁
• silver wedding    銀婚式
• silver wedding anniversary    銀婚式

العربيه (Arabic)
‏(الاسم) طبق فضي للمائدة, قطعه نقد فضيه, فضه (فعل) يطلي بالفضه, يفضض (صفه) فضي‏

עברית (Hebrew)
n. - ‮כסף (מתכת), מטבעות כסף, מצלצלים, כלי-כסף‬
v. tr. - ‮הכסיף (כיסה בצבע כסף)‬
v. intr. - ‮הכסיף, האפיר, הלבין (שיער)‬
adj. - ‮כספי, עשוי כסף, כסוף, מוכסף, צלול, מצלצל, שני במעלה‬

If you are unable to view some languages clearly, click here.

To select your translation preferences click here.