Element Silver, Ag, Transition Metal
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Silver History
Silver is known by the mankind since Pre-History, and its discovery is estimated happened to shortly after that of copper and gold, even though silver is also found in native form. Archaeological evidence suggests that Egyptians had been using silver for at least since predynastic period (5000 - 3400 B.C.). However before the middle of 2nd millennium B.C. silver was rarity and was more valuable than gold. Ancient Egyptian silver is believed to be obtained from Syria. Earliest silver articles from Egypt and other Western Asian countries contained from 1 to 38% gold and are considered to be smelted from natural alloys. Perhaps such alloys had been called "white gold".
Silver Occurrence
Silver is a rare element, its abundance in the Earth's crust thousands times less than that of copper. Estimated crustal abundance is less than 1 ppm. In Central Europe silver abundance is significantly higher than average, especially in Ore Mountains, the Harz, mountains of Bohemia and Saxony.
In the period of discovery, conquest and settlement in Americas, as great number of native solver had been found in Peru, Chili, Mexico and Bolivia. For instance, plate-shape silver nugget from Chili a weighed 1420 kg. Argentina is the only country which had been named after known chemical element. The last native silver nuggets were found in Ontario, Canada in 20th century. One of the most well-known of them, the Silver Pavement was 30 meters long and 18 meters high going deep into the Earth. A 20 tons ingot was smelted from it.
Native silver is very rare; this element is found mainly as a constituent part of minerals, which are known over 50. Silver is associated with tellurium, selenium, sulphur, and halogens. The most important of minerals is argentite Ag2S. Much more silver is spread up in complex polymetallic ores, which contain copper, lead and zinc.
Silver is a permanent constituent part of living organisms. In sea plants its abundance reaches 0.025 mg per 100 g of dry matter in terrestrial ones 0.006 mg; in sea animals 0.3-1.1, in mg, in terrestrial animals trace of element, 10-2-10-4 mg. Silver is accumulated in animals organisms in some glands, eye pigment layer and erythrocytes. Silver creates complexes with proteins, blood globulins, and haemoglobin. Blocking sulfhydryl group's silver prevents creations of active zones and inhibits various processes, for instance, deactivates myosin adenozintriphosphate activity. When parenterally injected, silver is bound mostly by blood globulins.
Silver Neighbours
D.I. Mendeleev Periodic Table |