Group 11, by modernIUPAC numbering,[1] is agroup ofchemical elements in theperiodic table, consisting ofcopper (Cu),silver (Ag),gold (Au), androentgenium (Rg), although no chemical experiments have yet been carried out to confirm that roentgenium behaves like the heavierhomologue to gold. Group 11, more specifically the first three members, are also known as thecoinage metals, due to their usage in minting coins[2]—while the rise in metal prices mean that silver and gold are no longer used for circulating currency, remaining in use for bullion, copper remains a common metal in coins to date, either in the form of copperclad coinage or as part of thecupronickel alloy.[citation needed] They were most likely the first three elements discovered.[3] Copper, silver, and gold all occur naturally inelemental form.[4][5]
All three stable elements of the group have been known since prehistoric times,[2] as all of them occur in metallic form in nature and noextraction metallurgy is necessary to produce them.
Copper was known and used around 4000 BC and many items, weapons and materials were made and used with copper.
The first evidence of silver mining dates back to 3000 BC, in Turkey and Greece, according to the RSC. Ancient people even figured out how to refine silver.
The earliest recorded metal employed by humans appears to be gold, which can be foundfree or "native". Small amounts of natural gold have been found in Spanish caves used during the latePaleolithic period, c. 40,000 BC. Gold artifacts made their first appearance at the very beginning of thepre-dynastic period in Egypt, at the end of the fifth millennium BC and the start of the fourth, and smelting was developed during the course of the 4th millennium BC; gold artifacts appear in the archeology ofLower Mesopotamia during the early 4th millennium BC.
Roentgenium was made in 1994 by bombarding nickel-64 atoms intobismuth-209 to make roentgenium-272.[6]
Like other groups, the members of this family show patterns inelectron configuration, especially in the outermost shells, resulting in trends in chemical behavior, although roentgenium is probably an exception:
All group 11 elements are relatively inert,corrosion-resistantmetals. Copper and gold are colored, but silver is not. Roentgenium is expected to be silvery, though it has not been produced in large enough amounts to confirm this.
These elements have lowelectrical resistivity so they are used for wiring. Copper is the cheapest and most widely used.Bond wires forintegrated circuits are usually gold. Silver and silver-plated copper wiring are found in some special applications.
Copper occurs in its native form in Chile, China, Mexico, Russia and the USA. Various natural ores of copper are:copper pyrites (CuFeS2),cuprite or ruby copper (Cu2O),copper glance (Cu2S),malachite (Cu(OH)2CuCO3), andazurite (Cu(OH)22CuCO3).
Copper pyrite is the principal ore, and yields nearly 76% of the world production of copper.
These metals, especially silver, have unusual properties that make them essential for industrial applications outside of their monetary or decorative value. They are all excellentconductors ofelectricity. The most conductive (by volume) of all metals are silver, copper and gold in that order. Silver is also the most thermally conductive element, and the most light-reflecting element. Silver also has the unusual property that the tarnish that forms on silver is still highly electrically conductive.
Copper is used extensively in electrical wiring and circuitry. Gold contacts are sometimes found in precision equipment for their ability to remain corrosion-free. Silver is used widely in mission-critical applications as electrical contacts and is also used inphotography (becausesilver nitrate reverts to metal on exposure to light),agriculture,medicine,sound reproduction and scientific applications.
Gold, silver, and copper are quite soft metals and so are easily damaged in daily use as coins. Precious metal may also be easily abraded and worn away through use. In theirnumismatic functions these metals must bealloyed with other metals to afford coins greater durability. The alloying with other metals makes the resulting coins harder, less likely to become deformed and more resistant to wear.
Gold coins:Gold coins are typically produced as either 90% gold (e.g. with pre-1933 US coins), or 22carat (91.66%) gold (e.g. currentcollectible coins andKrugerrands), with copper and silver making up the remaining weight in each case. Bullion gold coins are being produced with up to 99.999% gold (in theCanadian Gold Maple Leaf series).
Silver coins:Silver coins are typically produced as either 90% silver – in the case of pre-1965 US minted coins (which were circulated in many countries), orsterling silver (92.5%) coins for pre-1920 British Commonwealth and other silver coinage, with copper making up the remaining weight in each case. Old European coins were commonly produced with 83.5% silver. Modern silver bullion coins are often produced with purity varying from 99.9% to 99.999%.
Copper coins: Copper coins are often of quite high purity, around 97%, and are usually alloyed with small amounts ofzinc andtin.
Inflation has caused theface value of coins to fall below thehard currency value of the historically used metals. This had led to most modern coins being made ofbase metals –copper nickel (around 80:20, silver in color) is popular as are nickel-brass (copper (75), nickel (5) and zinc (20), gold in color),manganese-brass (copper, zinc, manganese, and nickel),bronze, or simple platedsteel.
Copper, although toxic in excessive amounts, isessential for life. It can be found inhemocyanin,cytochrome c oxidase and insuperoxide dismutase. Copper is shown to haveantimicrobial properties which make it useful for hospital doorknobs to keep diseases from being spread. Eating food in copper containers is known to increase the risk ofcopper toxicity.Wilson's disease is a genetic condition in which a protein important for excretion of excess copper is mutated such that copper builds up in body tissues, causing symptoms including vomiting, weakness, tremors, anxiety, and muscle stiffness.
Elemental gold and silver have no known toxic effects or biological use, although goldsalts can be toxic to liver and kidney tissue.[7][8] Like copper, silver also hasantimicrobial properties. The prolonged use of preparations containing gold or silver can also lead to the accumulation of these metals in body tissue; the results of which are irreversible but apparently harmless pigmentation conditions known aschrysiasis andargyria respectively.
Due to being short lived and radioactive,roentgenium has no biological use but it is likely extremely harmful due to its radioactivity.
^Hofmann, S.; Ninov, V.; Heßberger, F.P.; Armbruster, P.; Folger, H.; Münzenberg, G.; Schött, H. J.; Popeko, A. G.; Yeremin, A. V.; Andreyev, A. N.; Saro, S.; Janik, R.; Leino, M. (1995). "The new element 111".Zeitschrift für Physik A.350 (4):281–282.Bibcode:1995ZPhyA.350..281H.doi:10.1007/BF01291182.
