silver
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What is silver?
Silver (Ag) is a chemical element recognized for its white, lustrous appearance and high electrical conductivity. It is a precious metal, along with gold and platinum, and is known for its malleability, ductility, and resistance to atmospheric oxidation.
Silver is used in various applications, including coins, jewelry, and ornaments. Because silver has the highest known electrical and thermal conductivity of all metals, it is valuable in fabricating printed electrical circuits and as a vapor-deposited coating for electronic conductors. Silver is often alloyed with copper for jewelry and coinage, with sterling silver containing 92.5% silver.
Silver is found in the Earth's crust at a proportion of 0.05 part per million. It occurs in minerals like argentite (silver sulfide, Ag_2S) and tetrahedrite, often with lead, copper, and zinc sulfides.
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What is silver's chemical symbol on the periodic table?
The chemical symbol for silver on the periodic table is Ag. This symbol is derived from the Latin name for silver, argentum. Silver is a lustrous, white metal known for its beauty and electrical conductivity. It resides in Group 11 (Ib) and Period 5 of the periodic table, positioned between copper and gold, sharing intermediate properties with these metals.
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What are some common uses of silver in everyday life?
Silver is a precious metal valued for its brilliant white color, malleability, and resistance to oxidation.
Common Uses of Silver
- Ornaments and Jewelry Due to its beauty and workability, silver has been used in ornaments and jewelry since ancient times.
- Electrical Components Silver has the highest electrical and thermal conductivity of all metals, making it valuable in electrical circuits, contacts, and vapor-deposited coatings for electronic conductors.
- Silverware Silver is used for making silverware, including eating and serving utensils.
- Photography Silver compounds like silver chloride, silver bromide, and silver iodide are used in photography.
- Alloys Silver is often alloyed with other metals like copper to increase hardness and durability for use in jewelry, coinage, and dental applications. Sterling silver, for example, contains 92.5% silver and 7.5% copper.
- Brazing Fillers Silver brazing fillers are used for brazing steels and nonferrous metals.
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Why is silver considered a good conductor of electricity?
Silver is known for its high electrical conductivity, the highest of all metals. This is due to the mobility of its valence electrons, which move easily between atoms, carrying an electric current. Although silver has only one free electron per atom, its high electron mobility makes it a better conductor than metals with more free electrons. Impurities can interfere with the movement of electrons, so the purity of silver also contributes to its ability to conduct electricity effectively. For this reason, silver is used in electrical contacts and as a coating for electronic conductors.
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How is silver usually found and extracted from the Earth?
Silver is found in the Earth's crust at a concentration of about 0.05 part per million. Unlike gold, silver is present in many naturally occurring minerals, such as argentite (silver sulfide, AgāS). Silver is often found in lead, copper, and cobalt arsenide ores and is frequently associated with gold.
Silver-bearing ores are mined using open-pit or underground methods and then crushed. The ores are processed using flotation separation to concentrate the mineral values. Silver is often recovered as a by-product of copper and lead production through smelting and refining. The cyanide process, which involves treating ores with a dilute solution of sodium cyanide or calcium cyanide, is also used to extract silver.
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What are some interesting chemical properties or reactions of silver?
Silver is a precious metal known for its high electrical and thermal conductivity and its resistance to atmospheric oxidation. Although silver is one of the least chemically reactive transition elements, it is not inert. Silver dissolves in nitric acid and hot, concentrated sulfuric acid, as well as in oxidizing acids and cyanide solutions, forming the dicyanoargentate ion ([Ag(CN)_2]^-).
Silver doesn't react with moist air or dry oxygen, but it tarnishes quickly at room temperature when exposed to sulfur or hydrogen sulfide. Silver can act as a catalyst, uniquely converting ethylene to ethylene oxide, a precursor to many organic compounds.
Silver compounds have various oxidation states, with +1 being the most important. Silver nitrate ((AgNO_3)) is a crucial inorganic salt used to produce silver chloride, silver bromide, and silver iodide, all essential in photography. Divalent sulfur compounds, such as thiols and sulfides, readily bind to heavy metal ions like silver.
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silver (Ag), chemical element, a white lustrous metal valued for its decorative beauty and electrical conductivity. Silver is located in Group 11 (Ib) and Period 5 of the periodic table, between copper (Period 4) and gold (Period 6), and its physical and chemical properties are intermediate between those two metals.
| atomic number | 47 |
|---|---|
| atomic weight | 107.868 |
| melting point | 960.8 Ā°C (1,861.4 Ā°F) |
| boiling point | 2,212 Ā°C (4,014 Ā°F) |
| specific gravity | 10.5 (20 Ā°C [68 Ā°F]) |
| oxidation states | +1, +2, +3 |
| electron configuration | [Kr]4d105s1 |
Properties, uses, and occurrence
Together with gold and the platinum-group metals, silver is one of the so-called precious metals. Because of its comparative scarcity, brilliant white color, malleability, ductility, and resistance to atmospheric oxidation, silver has long been used in the manufacture of coins, ornaments, and jewelry. Silver has the highest known electrical and thermal conductivity of all metals and is used in fabricating printed electrical circuits and as a vapor-deposited coating for electronic conductors; it is also alloyed with such elements as nickel or palladium for use in electrical contacts. Silver also finds use as a catalyst for its unique ability to convert ethylene to ethylene oxide, which is a precursor of many organic compounds. Silver is one of the noblestāthat is, least chemically reactiveāof the transition elements.
Silver ornaments and decorations have been found in royal tombs dating back as far as 4000 bce. It is probable that both gold and silver were used as money by 800 bce in all countries between the Indus and the Nile.
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Silver is widely distributed in nature, but the total amount is quite small when compared with other metals; the metal constitutes 0.05 part per million of Earthās crust. Practically all sulfides of lead, copper, and zinc contain some silver. Silver-bearing ores may contain amounts of silver from a trace to several thousand troy ounces per avoirdupois ton, or about 10 percent.
Unlike gold, silver is present in many naturally occurring minerals. For silver the more important deposits commercially are such compounds as the minerals tetrahedrite and argentite (silver sulfide, Ag2S), which is usually associated with other sulfides such as those of lead and copper, as well as several other sulfides, some of which contain antimony as well. Silver is found generally in lead ores, copper ores, and cobalt arsenide ores and is also frequently associated with gold in nature. Most silver is derived as a by-product from ores that are mined and processed to obtain these other metals. Deposits of native (chemically free, or uncombined) silver are also commercially important.
Because the majority of the ores that contain silver also contain the important metals lead, copper, or zinc or a combination of the three, the silver-bearing fraction of these ores is frequently recovered as a by-product of copper and lead production. Pure silver is then recovered from the crude fraction by a combination of smelting and fire- or electrorefining. (For treatment of the recovery and refining of silver, see silver processing.)
| country | mine production 2016 (metric tons)* | % of world mine production | demonstrated reserves 2016 (metric tons)* | % of world demonstrated reserves** |
|---|---|---|---|---|
| *Estimate. | ||||
| **Includes silver obtainable from base-metal ores. | ||||
| ***Detail does not add to total given because of rounding. | ||||
| Source: U.S. Department of the Interior, Mineral Commodity Summaries 2017. | ||||
| Mexico | 5,600 | 20.7 | 37,000 | 6.5 |
| Peru | 4,100 | 15.2 | 120,000 | 21.1 |
| China | 3,600 | 13.3 | 39,000 | 6.8 |
| Chile | 1,500 | 5.6 | 77,000 | 13.5 |
| Australia | 1,400 | 5.2 | 89,000 | 15.6 |
| Poland | 1,400 | 5.2 | 85,000 | 14.9 |
| Russia | 1,400 | 5.2 | 20,000 | 3.5 |
| Bolivia | 1,300 | 4.8 | 22,000 | 3.9 |
| United States | 1,100 | 4.1 | 25,000 | 4.4 |
| other countries | 5,400 | 20 | 57,000 | 10 |
| world total | 27,000 | 100*** | 570,000 | 100*** |
Historically, a major use of silver has been monetary, in the form of reserves of silver bullion and in coins. By the 1960s, however, the demand for silver for industrial purposes, in particular the photographic industry, exceeded the total annual world production. In the early 21st century, digital cameras supplanted those that used film, but demand for silver from other sectorsāsuch as for sterling and plated silverware, ornaments, jewelry, coinage, electronic components, and photovoltaic cellsācontinued to be important.
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Alloys of silver with copper are harder, tougher, and more fusible than pure silver and are used for jewelry and coinage. The proportion of silver in these alloys is stated in terms of fineness, which means parts of silver per thousand of the alloy. Sterling silver contains 92.5 percent of silver and 7.5 percent of another metal, usually copper; i.e., it has a fineness of 925. Jewelry silver is an alloy containing 80 percent silver and 20 percent copper (800 fine). The yellow gold that is used in jewelry is composed of 53 percent gold, 25 percent silver, and 22 percent copper. (For treatment of silverās use in ornamental and household objects, see metalwork.)
Natural silver consists of a mixture of two stable isotopes: silver-107 (51.839 percent) and silver-109 (48.161 percent). The metal does not react with moist air or dry oxygen but is oxidized superficially by moist ozone. It is quickly tarnished at room temperature by sulfur or hydrogen sulfide. In the molten state, silver can dissolve up to 22 times its volume of oxygen; on solidification, most of the oxygen is expelled, a phenomenon known as the spitting of silver. This can be controlled by the addition of a deoxidant such as charcoal to the molten silver. Silver dissolves readily in nitric acid and in hot concentrated sulfuric acid. The metal will also dissolve in oxidizing acids and in solutions containing cyanide ions in the presence of oxygen or peroxides. Dissolution in cyanide solutions is attributable to the formation of the very stable dicyanoargentate, [Ag(CN)2]ā, ion.
Like copper, silver has a single s electron outside a completed d shell, but, in spite of the similarity in electronic structures and ionization energies, there are few close resemblances between silver and copper.
Compounds
For silver the preeminently important oxidation state in all of its ordinary chemistry is the state +1, although the states +2 and +3 are known.
Silver compounds include silver chloride (AgCl), silver bromide (AgBr), and silver iodide (AgI). Each of these salts is used in photography. Silver chloride serves as the light-sensitive material in photographic printing papers and, together with silver bromide, in certain films and plates. The iodide is also used in the manufacture of photographic papers and films, as well as in cloud seeding for artificial rainmaking and in some antiseptics. All three halides are derived from silver nitrate (AgNO3), which is the most important of the inorganic silver salts. Besides these other salts, silver nitrate is also the starting material for the production of the silver cyanide used in silver plating.