- 苏萦
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Silver is a chemical element with the chemical symbol Ag 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 (electrum) and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a by-product of copper, gold, lead, and zinc refining.
Silver has been known since ancient times and has long been valued as a precious metal, used to make ornaments, jewelry, high-value tableware, utensils (hence the term silverware), and currency coins. Today, silver metal is used in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film and dilute solutions of silver nitrate and other silver compounds are used as disinfectants. Although the antimicrobial uses of silver have largely been supplanted by the use of antibiotics, further research into its clinical potential is in progress.
Silver is a very ductile and 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 and tarnishability have prevented it from being widely used in place of copper for electrical purposes, though 13540 tons were used in the electromagnets used for enriching uranium during World War II (mainly because of the wartime shortage of copper). Another notable exception is in high-end audio cables.
Among metals, pure silver has the highest thermal conductivity(the non-metal diamond and superfluid helium II are higher), the whitest color, and the highest optical reflectivity(although aluminium slightly outdoes it in parts of the visible spectrum, and it 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 to form a black layer of silver sulfide which can be cleaned off with dilute hydrochloric acid. 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 +3 compounds (for example, potassium tetrafluoroargentate: K[AgF4]) are known.
- 阿啵呲嘚
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楼上绝对复制的,BS
Silver is a kind of metal,which has silvery white color 。There is few silver in the earth"s crust。 now silver is used to making compound metal,chemistry equipments and so on. In the past people use it to make coin, personal ornaments... silver has good electric conductivity and shine 。
- 余辉
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Silver is a soft white precious univalent metallic element having the highest electrical and thermal conductivity of any metal; occurs in argentite and in free form; used in coins and jewelry and tableware and photography.
silver was found in acient time.
- 我不懂运营
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sliver