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Copyright (c) 2006-2014 MindTouch Inc.
This file and accompanying files are licensed under the MindTouch Master Subscription Agreement (MSA).
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The use of Copper dates back far into history. Copper beads have been found in what is now modern Iraq, dating back to 9000 BCE. The metal is relatively easy to mine and refine, contributing to its early and widespread use. Being soft, however, it is unsuitable for making reliable tools and weapons. Early metalsmiths as far back as 3000 BCA learned to combine copper with other metals to produce more durable alloys. Brass (copper and zinc) and bronze (copper and tin) are two examples. The symbol and name for copper are from the Latin cuprum, which literally means "from the island of Cyprus", an early source of copper ore.
Before 1982 U.S. pennies were pure copper. Now they are mostly zinc with a thin shell of copper. Most copper that is mined today is refined and drawn into wire for use in the electrical industries. A significant portion is also used in manufacturing water pipe.
Copper, of course, has a characteristic color which most people recognize. It is one of the best electrical conductors and resists corrosion from most acids (except nitric and hot concentrated sulfuric). When exposed to the elements for a period of time it develops a greenish coating or patina which is copper(II) carbonate, a protective coating that prevents further wear.
Silver (name from the Anglo-Saxon sioful, symbol from the Latin argentium) is considered a precious metal. It is found only to the extent of 0.05 parts per million in the earth (i.e., you have to dig up 20 million shovels full of dirt to get one shovel full of silver!). Knowledge of the metal is of ancient origins. Refining methods are mentioned in the Hebrew scriptures and ancient Egyptian writing. Silver was once considered more valuable than gold, probably because gold was easier to locate and refine at the time. Silver is ten times more abundant than gold.
Pure silver metal is the best conductor of heat and electricity. Pure silver would be too soft for jewelry and utensils so it is usually alloyed with at least one other metal. Sterling silver, for example, is usually about 93% silver and 7% other metals, mostly copper.
Silver can be found in high concentrations as argentite, Ag2S, but most is recovered in the refining processes of other metals such as copper.
Most compounds of silver are light sensitive and a lot of silver bromide and silver chloride are used by the photographic industry.
On average, a million tons of earth contain just ten pounds of gold. This scarcity, as well as its beauty and chemical properties account for its high value from ancient times. The name for the element is of Anglo-Saxon origin and the symbol comes from the Latin aurum, meaning "shining dawn".
Gold metal has a distinctive yellow color and is incredibly malleable and ductile. A single ounce of pure gold can be beaten out to a sheet that is about 300 feet square!! Pure gold is easily cut with a knife. Few elements react with gold under normal conditions and so most gold is recovered as small flakes of the pure element.
Gold is a very good conductor and is often used to plate electrical contacts since it resists corrosion so well. It also is a good reflector of heat-carrying infra-red radiation.
The world's oceans contain billions of tons of gold but it is too widely dispersed to be recovered (two-tenths of an ounce per million tons of water).
Announcement of the discovery of element 111 was made in the popular press in January of 1995. Reports from the GSI labs in Germany indicate that nickel ions were used to bombard a bismuth target. The IUPAC in 2004 confirmed the discovery by S. Hoffmann and his coworkers in Darmstadt, Germany. The researchers proposed the name Roentgenium, with symbol Rg. Final approval was given in November 2004.
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