Silver is a chemical element with symbol Ag (Greek: ??????? rguros, Latin: argentum, both from the Indo-European root *h2er?- for "grey" or "shining") and atomic number 47. A soft, white, lustrous transition metal, it possesses the highest electrical conductivity, thermal conductivity and reflectivity 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. More abundant than gold, silver metal has in many premodern monetary systems functioned as coinable specie, sometimes even alongside gold. In addition, silver has numerous applications beyond currency, such as in solar panels, water filtration, jewelry and ornaments, high-value tableware and utensils (hence the term silverware), and also as an investment in the forms of coins and bullion. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings and in catalysis of chemical reactions. Its compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other silver compounds are used as disinfectants and microbiocides (oligodynamic effect), added to bandages and wound-dressings, catheters and other medical instruments.Contents [hide] 1 Characteristics2 Isotopes3 Compounds4 Applications4.1 Currency4.2 Jewelry and silverware4.3 Solar energy4.4 Air conditioning4.5 Water purification4.6 Dentistry4.7 Photography and electronics4.8 Glass coatings4.9 Other industrial and commercial applications4.10 Biology4.11 Medicine4.12 Investing4.13 Clothing5 History5.1 World War II6 Occurrence and extraction7 Price8 Human exposure and consumption8.1 Monitoring exposure8.2 Use in food9 See also10 References11 External linksCharacteristics[edit]Silver 1000 oz t (~31 kg) bullion barSilver is produced during certain types of supernova explosions by nucleosynthesis from lighter elements through the r-process, a form of nuclear fusion that produces many elements heavier than iron, of which silver is one.[3]Silver is a very ductile, malleable (slightly less so than gold), univalent coinage metal, with a brilliant white metallic luster that can take a high degree of polish.[4] Protected silver has higher optical reflectivity than aluminium at all wavelengths longer than ~450 nm.[5] At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm.[6]The electrical conductivity of silver is the highest 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. An exception to this is in radio-frequency engineering, particularly at VHF and higher frequencies, where silver plating is employed to improve electrical conductivity of parts, including wires. Silver also has the lowest contact resistance of any metal.[citation needed] During World War II in the US, 13,540 tons were used in the electromagnets used for enriching uranium, mainly because of the wartime shortage of copper.[7][8][9]Pure silver has the highest thermal conductivity of any metal, although that of the nonmetal carbon in the form of diamond and superfluid helium II are higher.[citation needed]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.[10] The most common oxidation state of silver is +1 (for example, silver nitrate, AgNO3); the less common +2 compounds (for example, silver(II) fluoride, AgF2), and the even less common +3 (for example, potassium tetrafluoroargentate(III), KAgF4) and even +4 compounds (for example, potassium hexafluoroargentate(IV), K2AgF6)[11] are also known.Silver is a chemical element with symbol Ag (Greek: ??????? rguros, Latin: argentum, both from the Indo-European root *h2er?- for "grey" or "shining") and atomic number 47. A soft, white, lustrous transition metal, it possesses the highest electrical conductivity, thermal conductivity and reflectivity 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. More abundant than gold, silver metal has in many premodern monetary systems functioned as coinable specie, sometimes even alongside gold. In addition, silver has numerous applications beyond currency, such as in solar panels, water filtration, jewelry and ornaments, high-value tableware and utensils (hence the term silverware), and also as an investment in the forms of coins and bullion. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings and in catalysis of chemical reactions. Its compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other silver compounds are used as disinfectants and microbiocides (oligodynamic effect), added to bandages and wound-dressings, catheters and other medical instruments.Contents [hide] 1 Characteristics2 Isotopes3 Compounds4 Applications4.1 Currency4.2 Jewelry and silverware4.3 Solar energy4.4 Air conditioning4.5 Water purification4.6 Dentistry4.7 Photography and electronics4.8 Glass coatings4.9 Other industrial and commercial applications4.10 Biology4.11 Medicine4.12 Investing4.13 Clothing5 History5.1 World War II6 Occurrence and extraction7 Price8 Human exposure and consumption8.1 Monitoring exposure8.2 Use in food9 See also10 References11 External linksCharacteristics[edit]Silver 1000 oz t (~31 kg) bullion barSilver is produced during certain types of supernova explosions by nucleosynthesis from lighter elements through the r-process, a form of nuclear fusion that produces many elements heavier than iron, of which silver is one.[3]Silver is a very ductile, malleable (slightly less so than gold), univalent coinage metal, with a brilliant white metallic luster that can take a high degree of polish.[4] Protected silver has higher optical reflectivity than aluminium at all wavelengths longer than ~450 nm.[5] At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm.[6]The electrical conductivity of silver is the highest 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. An exception to this is in radio-frequency engineering, particularly at VHF and higher frequencies, where silver plating is employed to improve electrical conductivity of parts, including wires. Silver also has the lowest contact resistance of any metal.[citation needed] During World War II in the US, 13,540 tons were used in the electromagnets used for enriching uranium, mainly because of the wartime shortage of copper.[7][8][9]Pure silver has the highest thermal conductivity of any metal, although that of the nonmetal carbon in the form of diamond and superfluid helium II are higher.[citation needed]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.[10] The most common oxidation state of silver is +1 (for example, silver nitrate, AgNO3); the less common +2 compounds (for example, silver(II) fluoride, AgF2), and the even less common +3 (for example, potassium tetrafluoroargentate(III), KAgF4) and even +4 compounds (for example, potassium hexafluoroargentate(IV), K2AgF6)[11] are also known.