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{{Infobox copper}}
{{Infobox copper}}


'''Copper''' ({{pronEng|ˈkɒpɚ}}) is a [[chemical element]] with the symbol '''Cu''' ({{lang-la|cuprum}}) and [[atomic number]] 29.
Conway Middle School! conway middle school is full of haten bitches. you can't turn the damn corner with out a bitch haten on you. and the Niggaz in this school are so damn stuck up i noe it sounds weird because its guys but damn the spend more time in the mirror then chicas do. And the funny part bout the haten bitches wen u step 2 them they denie every thing they be so fucking scared it seemes as if the are bout to piss on them shelfs.But 2 put Conway Middle School in a big bubble it SUCKES DICK!!!!!!
It is a [[ductile]] [[metal]] with excellent [[electrical conductivity]] and is rather soft in its pure state and has a pinkish luster which is (beside [[gold]]) unusual for metals which are normally silvery white. It finds extensive use as an electrical conductor, heat conductor, as a building material, and as a component of various [[alloy]]s.

Copper is an essential trace nutrient to all high plants and animals. In animals, including humans, it is found primarily in the [[bloodstream]], as a [[Cofactor (biochemistry)|co-factor]] in various [[enzymes]], and in copper-based [[pigments]]. However, in sufficient amounts, copper can be poisonous and even fatal to organisms.

Copper has played a significant part in the history of humankind, which has used the easily accessible uncompounded metal for thousands of years. Several early civilizations have early evidence of using copper. During the [[Roman Empire]], copper was principally mined on [[Cyprus]], hence the origin of the name of the metal as Cyprium, "metal of Cyprus", later shortened to Cuprum.

A number of countries, such as [[Chile]] and the [[United States]], still have sizable reserves of the metal which are extracted through large open pit mines, however like [[tin]] there may be insufficient reserves to sustain current rates of consumption.<ref>{{cite web |url=http://www.livescience.com/strangenews/060119_scarce_metals.html |title=Earth's Limited Supply of Metals Raises Concern |accessdate=2008-03-16}}</ref> High demand relative to supply has caused a price spike in the 2000s{{Fact|date=March 2008}}.

Copper also has a significant presence as a decorative metal art. It can also be used as an anti-germ surface that can add to the anti-bacterial and antimicrobial features of buildings such as hospitals. <ref>{{cite news |title=Regulators Stamp Copper as a Germ Killer |author=Barnaby J. Feder |date=[[March 26]], [[2008]] |url=http://www.nytimes.com/2008/03/26/business/26microbes.html?_r=1&scp=2&sq=copper&st=nyt&oref=slogin |publisher=New York Times}}</ref>

== History ==
Copper, as [[native copper]], is one of the few metals to naturally occur as an uncompounded mineral. Copper was known to some of the oldest civilizations on record, and has a history of use that is at least 10,000 years old. No one knows exactly when copper was first discovered, but earliest estimates place this event around 9000 BC.<ref>http://www.csa.com/discoveryguides/copper/overview.php</ref> A copper pendant was found in what is now northern [[Iraq]] that dates to 8700 [[Before Christ|BC]]. By 5000 BC, there are signs of copper [[smelting]]: the refining of copper from simple copper compounds such as [[malachite]] or [[azurite]]. Among archaeological sites in Anatolia, [[Çatal Höyük]] (~6000 BC) features native copper artifacts and smelted lead beads, but no smelted copper. But [[Can Hasan]] (~5000 BC) had access to smelted copper; this site has yielded the oldest known cast copper artifact, a copper [[Mace (club)|mace]] head.
[[Image:Copper Ingot Crete.jpg|left|thumb|200px|Ancient Copper [[ingot]] from [[Zakros]], [[Crete]] is shaped in the form of an animal skin typical for that era.]]

Copper smelting appears to have been developed independently in several parts of the world. In addition to its development in Anatolia by 5000 BC, it was developed in China before 2800 BC, in the Andes around 2000 BC, in Central America around 600 AD, and in West Africa around 900 AD.<ref>Richard Cowen, [http://www.geology.ucdavis.edu/~cowen/~GEL115/115CH3.html ''Essays on Geology, History, and People'', Chapter 3: "Fire and Metals: Copper"].</ref> Copper is found extensively in the [[Indus Valley Civilization]] by the 3rd millennium BC.<ref>[http://web.archive.org/web/20070519194706/http://www.harappa.com harappa.com] (Web archive)</ref> In Europe, [[Ötzi the Iceman]], a well-preserved male dated to 3300-3200 BC, was found with an axe tipped with copper that was 99.7% pure. High levels of [[arsenic]] in his hair suggest he was involved in copper smelting.

There exist copper and [[bronze]] artifacts from [[Sumer]]ian cities that date to 3000 BC, and [[Ancient Egypt|Egyptian]] artifacts of copper and copper-[[tin]] alloys nearly as old. In one pyramid, a copper plumbing system was found that is 5000 years old. The Egyptians found that adding a small amount of tin made the metal easier to cast, so copper-tin ([[bronze]]) alloys were found in Egypt almost as soon as copper was found. Very important sources of copper in the Levant were located in [[Timna valley]] (Palestine) and Faynan (biblical [[Punon]], Jordan).<ref>J.M. Tebes [http://dialnet.unirioja.es/servlet/articulo?codigo=2314512 "A Land whose Stones are Iron, and out of whose Hills You can Dig Copper": The Exploitation and Circulation of Copper in the Iron Age Negev and Edom], ''DavarLogos'' 6/1 (2007)]</ref>

In the Americas production in the [[Old Copper Complex]], located in present day Michigan and Wisconsin, was dated back to between 6000 to 3000 BC.<ref>{{cite web |url=http://www.uwfox.uwc.edu/academics/depts/tpleger/oldcopper.html |title=The Old Copper Complex of the Western Great Lakes |author=Thomas C. Pleger, Ph.D. |publisher=UW-Fox Valley Anthropology |year=2000 |accessdate=2007-08-15}}</ref>

By 2000 BC, Europe was using bronze. The use of [[bronze]] became so pervasive in a certain era of civilization (approximately 2500 BC to 600 BC in Europe) that it has been named the [[Bronze Age]]. The transitional period in certain regions between the preceding [[Neolithic]] period and the Bronze Age is termed the [[Chalcolithic]] ("copper-stone"), with some high-purity copper tools being used alongside stone tools. [[Brass]] (copper-zinc) was known to the Greeks, but only became a significant supplement to bronze during the Roman empire.[[Image:Venus symbol.svg|left|thumb|100px|In [[alchemy]] the symbol for copper, perhaps a stylized mirror, was also the symbol for the goddess and planet [[Venus (planet)|Venus]].]]

In Greek the metal was known by the name ''chalkos'' (χαλκός). Copper was a very important resource for the Romans, Greeks and other ancient peoples. In Roman times, it became known as ''aes Cyprium'' (''aes'' being the generic Latin term for copper alloys such as [[bronze]] and other metals, and ''Cyprium'' because so much of it was mined in [[Cyprus]]). From this, the phrase was simplified to ''cuprum'' and then eventually Anglicized into the English ''copper''. Copper was associated with the goddess [[Aphrodite]]/[[Venus (goddess)|Venus]] in mythology and [[alchemy]], owing to its lustrous beauty, its ancient use in producing mirrors, and its association with [[Cyprus]], which was sacred to the goddess.

===British Isles===
[[Image:westmine.jpg|right|thumb|West Mine at Alderley Edge]]
During the Bronze Age, copper was mined in the British Isles mainly in the following locations:
* South West [[County Cork]]
* [[Ceredigion]], West [[Wales]] (e.g. [[Cwmystwyth]])
* North Wales (e.g. [[Great Orme]])
* [[Anglesey]] ([[Parys Mountain]])
* [[Cheshire]] ([[Alderley Edge]])
* The [[Staffordshire Moorlands]] (e.g. [[Ecton, Staffordshire|Ecton]] Mine)
* The [[Isle of Man]], in the [[Irish Sea]] near the centre of the [[British Isles]].
At [[Great Orme]] in North Wales, such working extended for a depth of 70 metres.<ref>{{cite book |author=O’Brien, W. |title=Bronze Age Copper Mining in Britain and Ireland |publisher=Shire Publications Ltd |year=1997 |isbn=0747803218}}</ref> At [[Alderley Edge]] in [[Cheshire]], carbon dates have established mining at around 2280 to 1890 BC (at 95% probability).<ref>Timberlake and Prag, 2005</ref>

===United States===
[[Image:TamarackMiners CopperCountryMI sepia.jpg|thumb|Miners at the [[Tamarack Mine]] in [[Copper Country]], Michigan, USA in 1905.]]
[[Copper mining in the United States]] began with marginal workings by Native Americans and some development by early Spaniards. Native copper is known to have been extracted from sites on [[Isle Royale]] with primitive stone tools between 800 and 1600. Europeans were mining copper in [[Connecticut]] as early as 1709. Perhaps the oldest operating large-scale copper mine was the historic Elizabeth Mine in Vermont. Dating to the 1700s, "the Liz" produced copper until it was closed in 1958. Westward movement also brought an expansion of copper exploitation with developments of significant deposits in [[Michigan]] and [[Arizona]] during the 1850s and then in [[Montana]] during the 1860s.

Native copper was mined extensively in [[Michigan]]'s [[Keweenaw Peninsula]] with the heart of extraction at the productive [[Calumet and Hecla Mining Company]]. Arizona had many notable deposits including the Copper Queen in Bisbee and the United Verde in Jerome. The Anaconda in Butte, Montana became the nation's chief copper supplier by 1886.

Copper is mined in many other areas of the United States, including [[Utah]], [[Nevada]] and [[Tennessee]]. Copper is the [[List of U.S. state minerals, rocks, stones and gemstones|state mineral]] for Utah.

==Isotopes==
{{main|Isotopes of copper}}
There are two stable [[isotope]]s, <sup>63</sup>Cu and <sup>65</sup>Cu, along with a couple dozen [[radioisotope]]s. The vast majority of radioisotopes have half lives on the order of minutes or less; the longest lived, <sup>67</sup>Cu, has a half life of 61.8 hours. See also [[isotopes of copper]].

==Notable characteristics==
[[Image:029-Cu.jpg|thumb|left|150px|Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color.]]
[[Image:Metallic bond Cu.svg|thumb|right|150px|Copper exists as a [[metallic bond|metallically bonded]] substance, allowing it to have a wide variety of metallic properties.]]

Copper is a reddish-colored [[metal]]; it has its characteristic color because of its [[band structure]]. In its liquefied state, a pure copper surface without ambient light appears somewhat greenish, a characteristic shared with gold. When liquid copper is in bright ambient light, it retains some of its pinkish luster.

Copper occupies the same family of the periodic table as silver and gold, since they each have one s-orbital electron on top of a filled [[electron shell]]. This similarity in electron structure makes them similar in many characteristics. All have very high thermal and electrical conductivity, and all are malleable metals.

===Conductivity===
Copper has a high [[electrical conductivity|electrical]] and [[thermal conductivity]], second only to [[silver]] among pure metals at [[room temperature]].<ref name="LANL">[http://periodic.lanl.gov/elements/29.html Los Alamos National Laboratory - Copper]</ref>

===Corrosion===
'''Pure water and air'''<br>
Copper is a metal that does not react with water (H<sub>2</sub>O), but the oxygen of the air will react slowly at room temperature to form a layer of brown-black copper oxide on copper metal.

[[Image:Copper in water pourbiax diagram.png‎|thumb|right|150px|The [[Pourbaix diagram]] for copper in pure water, perchloric acid or sodium It can be seen that copper in "pure" water is more noble than hydrogen. As a result it does not corrode in oxygen free water and the corrosion rate in oxygenated water is low.

hydroxide<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]

It is important to note that in contrast to the oxidation of iron by wet air that the layer formed by the reaction of air with copper has a protective effect against further corrosion. On old copper roofs a green layer of copper carbonate, called [[verdigris]] or [[patina]], can often be seen. Another notable example of this is on the [[Statue of Liberty]].

'''Sulfide media'''

Copper metal does react with [[hydrogen sulfide]]- and [[sulfide]]-containing solutions. A series of different copper sulfides can form on the surface of the copper metal.

[[Image:Copper in sulphide media pourbiax diagram.png|thumb|left|150px|The [[Pourbaix diagram]] for copper in a sulfide containing aqueous medium<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]

Note that the copper sulfide area of the plot is very complex due to the existence of many different sulfides, a close up is also provided to make the graph more clear. It is clear that the copper is now able to corrode even without the need for oxygen as the copper is now less noble than [[hydrogen]]. This can be observed in every day life when copper metal surfaces [[tarnish]] after exposure to air which contains sulfur compounds.

[[Image:Close up of copper sulphide pourbiax diagram.png‎|thumb|right|150px|The [[Pourbaix diagram]] for copper in a sulfide containing aqueous medium<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]

'''Ammonia media'''

Copper does react with oxygen-containing ammonia solutions because the ammonia forms water-soluble copper complexes. The formation of these complexes causes the corrosion to become more thermodynamically favored than the corrosion of copper in an identical solution that does not contain the ammonia.

[[Image:Copper in 10M ammonia pourbiax diagram.png‎|thumb|left|150px|The [[Pourbaix diagram]] for copper in 10 M ammonia solution<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]

'''Chloride media'''

Copper does react with a combination of oxygen and hydrochloric acid to form a series of copper chlorides. It is interesting to note that if copper(II) chloride (green/blue) is boiled with copper metal (with little or no oxygen present) then white copper(I) chloride will be formed.

[[Image:Copper in chloride media more copper pourbiax.png‎‎|thumb|right|150px|The [[Pourbaix diagram]] for copper in a chloride solution<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]

===Mechanical properties===

A single crystal copper consists of a few micrometres of small crystals. In this form of crystal (c), the yield stress is high and crystal undergoes a large amount of elastic deformation before going into the plastic deformation region. The plastic deformation region has an unpredictable outcome. The stress level decreases significantly as necking begins to occur.

[[Polycrystal copper]] has many crystal of different geometries combined. The plastic deformation of polycrystal is similar to mild steel. Copper has a high ductility and will continue to elongate as stress is applied. It is very useful in copper wire drawing.

Numerous [[copper alloys]] exist, many with important historical and contemporary uses. [[Speculum metal]] and [[bronze]] are alloys of copper and [[tin]]. [[Brass]] is an alloy of copper and [[zinc]]. [[Monel]] metal, also called [[cupronickel]], is an alloy of copper and [[nickel]]. While the metal "bronze" usually refers to copper-tin alloys, it also is a generic term for any alloy of copper, such as [[aluminium bronze]], silicon bronze, and manganese bronze.

===Germicidal effect===
Copper is germicidal, via the [[oligodynamic effect]]. For example, brass doorknobs disinfect themselves of many bacteria within a period of eight hours.<ref>{{cite web |url=http://members.vol.at/schmiede/MsgverSSt.html |title=Doorknobs: A Source of Nosocomial Infection? |author=Phyllis J. Kuhn, Ph.D. |year=1983 |accessdate=2007-08-15}}</ref> [[Antimicrobial]] properties of copper are effective against [[MRSA]],<ref name="pmid16650507">{{cite journal |author=Noyce JO, Michels H, Keevil CW |title=Potential use of copper surfaces to reduce survival of epidemic meticillin-resistant Staphylococcus aureus in the healthcare environment |journal=J. Hosp. Infect. |volume=63 |issue=3 |pages=289–97 |year=2006 |pmid=16650507 |doi=10.1016/j.jhin.2005.12.008}}</ref> [[Escherichia coli]]<ref name="pmid16751537">{{cite journal |author=Noyce JO, Michels H, Keevil CW |title=Use of copper cast alloys to control Escherichia coli O157 cross-contamination during food processing |journal=Appl. Environ. Microbiol. |volume=72 |issue=6 |pages=4239–44 |year=2006 |pmid=16751537 |doi=10.1128/AEM.02532-05}}</ref> and other [[pathogen]]s.<ref name="pmid18069086">{{cite journal |author=Mehtar S, Wiid I, Todorov SD |title=The antimicrobial activity of copper and copper alloys against nosocomial pathogens and Mycobacterium tuberculosis isolated from healthcare facilities in the Western Cape: an in-vitro study |journal=J. Hosp. Infect. |volume=68 |issue=1 |pages=45–51 |year=2008 |pmid=18069086 |doi=10.1016/j.jhin.2007.10.009}}</ref><ref name="pmid17567632">{{cite journal |author=Gant VA, Wren MW, Rollins MS, Jeanes A, Hickok SS, Hall TJ |title=Three novel highly charged copper-based biocides: safety and efficacy against healthcare-associated organisms |journal=J. Antimicrob. Chemother. |volume=60 |issue=2 |pages=294–9 |year=2007 |pmid=17567632 |doi=10.1093/jac/dkm201}}</ref><ref name="pmid17259354">{{cite journal |author=Noyce JO, Michels H, Keevil CW |title=Inactivation of influenza A virus on copper versus stainless steel surfaces |journal=Appl. Environ. Microbiol. |volume=73 |issue=8 |pages=2748–50 |year=2007 |pmid=17259354 |doi=10.1128/AEM.01139-06}}</ref> In colder temperature, longer time is required to kill bacteria.

== Occurrence and modern industry==
{{see|Peak copper}}
{{update}}
[[Image:Chuquicamata-002.jpg|200px|left|thumb|[[Chuquicamata]] ([[Chile]]). One of the largest [[open-pit mining|open pit]] copper [[mining|mines]] in the world.]]
[[Image:2005copper (mined).PNG|thumb|200px|left|Copper output in 2005]]
[[Image:Copper - world production trend.svg|thumb|left|World production trend]]
[[Image:Historical copper price.png|thumb|right|Evolution of the historical copper price<br>source : [http://minerals.usgs.gov/ds/2005/140/copper.xls minerals.usgs.gov] (XLS)<br> Current price is at least four times higher than the 2002 value.]]
[[Image:Coppernuggets.jpg|200px|right|thumb|Native Copper Placer Nuggets]]
[[Image:CopperMineralUSGOV.jpg|200px|right|thumb|Native copper]]

In 2005, Chile was the top mine producer of copper with at least one-third world share followed by the USA, Indonesia and Peru, reports the [[British Geological Survey]].

Copper can be found as [[native copper]] in [[mineral]] form. Minerals such as the [[sulfide]]s: [[chalcopyrite]] (CuFeS<sub>2</sub>), [[bornite]] (Cu<sub>5</sub>FeS<sub>4</sub>), [[covellite]] (CuS), [[chalcocite]] (Cu<sub>2</sub>S) are sources of copper, as are the [[carbonate]]s: [[azurite]] (Cu<sub>3</sub>(CO<sub>3</sub>)<sub>2</sub>(OH)<sub>2</sub>) and [[malachite]] (Cu<sub>2</sub>CO<sub>3</sub>(OH)<sub>2</sub>) and the oxide: [[cuprite]] (Cu<sub>2</sub>O).

Most copper ore is mined or [[copper extraction|extracted]] as copper sulfides from large [[open pit mine]]s in [[porphyry copper]] deposits that contain 0.4 to 1.0 percent copper. Examples include: [[Chuquicamata]] in [[Chile]] and [[El Chino Mine]] in [[New Mexico]]. The average abundance of copper found within [[crustal rocks]] is approximately 68 [[parts per million|ppm]] by mass, and 22 [[parts per million|ppm]] by [[atoms]].

The [[Intergovernmental Council of Copper Exporting Countries]] (CIPEC), defunct since 1992, once tried to play a similar role for copper as [[OPEC]] does for [[Petroleum|oil]], but never achieved the same influence, not least because the second-largest producer, the [[United States]], was never a member. Formed in 1967, its principal members were [[Chile]], [[Peru]], [[Zaire]], and [[Zambia]].

The copper price has quintupled from the 60-year low in [[1999]], rising from [[us dollar|US$]]0.60 per [[Pound (mass)|pound]] ([[us dollar|US$]]1.32/[[kg]]) in June 1999 to US$3.75 per [[Pound (mass)|pound]] ([[us dollar|US$]]8.27/[[kg]]) in May [[2006]], where it dropped to [[us dollar|US$]]2.40 ([[us dollar|US$]]5.29/[[kg]]) in February [[2007]] then rebounded to [[us dollar|US$]]3.50 ([[us dollar|US$]]7.71/[[kg]] =
[[pound sterling|£]]3.89 = [[euro|€]]5.00) in April [[2007]].<ref>[http://metalspotprice.com/copper-trends/ Copper Trends: Live Metal Spot Prices], MetalSpotPrice.com</ref>

The Earth has an estimated 61 years of copper reserves remaining.<ref> New Scientist. May 26, 2007.</ref> Environmental analyst, [[Lester Brown]], however, has suggested copper might run out within 25 years based on a reasonable extrapolation of 2% growth per year.<ref name="Brown">{{cite book|author=Brown, Lester|title=Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble|publisher=New York: W.W. Norton|date=2006|page=109|isbn=0393328317}}</ref>

Copper has been in use at least 10,000 years, but more than 95 percent of all copper ever mined and smelted has been extracted since 1900. And as India and China race to catch up with the West, copper supplies are getting tight.<ref name=Leonard2006>{{cite web
|url=http://www.salon.com/tech/htww/2006/03/02/peak_copper/index.html
|title=Peak copper?
|publisher=Salon - How the World Works
|author=Andrew Leonard
|date=2006-03-02
|language=English
|accessdate=2008-03-23
}}</ref> Copper is among the most important industrial metals. Like fossil fuels, copper is a finite resource. [[Peak copper]] is the point in time at which the maximum global [[Copper|copper]] production rate is reached, according to [[Hubbert peak theory]], the rate of production enters its terminal decline.

{{further|[[Copper extraction techniques]]}}

== Compounds ==
Common [[oxidation state]]s of copper include the less stable copper(I) state, Cu<sup>+</sup>; and the more stable copper(II) state, Cu<sup>2+</sup>, which forms blue or blue-green salts and solutions. Under unusual conditions, a 3+ state and even an extremely rare 4+ state can be obtained. Using old nomenclature for the naming of salts, copper(I) is called ''cuprous'', and copper(II) is ''cupric''. In [[oxidation]] copper is mildly [[Base (chemistry)|basic]].

[[Copper(II) carbonate]] is green from which arises the unique appearance of copper-clad roofs or domes on some buildings. [[Copper(II) sulfate]] forms a blue crystalline penta[[hydrate]] which is perhaps the most familiar copper compound in the laboratory. It is used as a [[fungicide]], known as Bordeaux mixture.

There are two stable copper oxides, [[copper(II) oxide]] (CuO) and [[copper(I) oxide]] (Cu<sub>2</sub>O). Copper oxides are used to make [[yttrium]] [[barium]] copper oxide (YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub>) or [[YBCO]] which forms the basis of many [[unconventional superconductors]].

*'''Copper(I) compounds''': [[copper(I) chloride]], [[copper(I) bromide]], [[copper(I) iodide]], [[copper(I) oxide]].

*'''Copper(II) compounds''': [[copper(II) acetate]], [[copper(II) carbonate]], [[copper(II) chloride]], [[copper(II) hydroxide]], [[copper(II) nitrate]], [[copper(II) oxide]], [[copper(II) sulfate]], [[copper(II) sulfide]], [[copper(II) tetrafluoroborate]], [[copper(II) triflate]].

*'''Copper(III) compounds''', rare: [[potassium hexafluorocuprate]] (K<sub>3</sub>CuF<sub>6</sub>)

*'''Copper(IV) compounds''', extremely rare: [[caesium hexafluorocuprate]] (Cs<sub>2</sub>CuF<sub>6</sub>)

{{seealso|Category:Copper compounds}}

==== Tests for copper(II) ion ====
Add aqueous [[sodium hydroxide]]. A blue precipitate of [[copper(II) hydroxide]] should form.

Ionic equation:

:Cu<sup>2+</sup>(aq) + 2OH<sup>−</sup>(aq) → Cu(OH)<sub>2</sub>(s)

The full equation shows that the reaction is due to hydroxide ions deprotonating the hexaaquacopper (II) complex:

:[Cu(H<sub>2</sub>O)<sub>6</sub>]<sup>2+</sup>(aq) + 2 OH<sup>−</sup>(aq) → Cu(H<sub>2</sub>O)<sub>4</sub>(OH)<sub>2</sub>(s) + 2 H<sub>2</sub>O (l)

Adding [[ammonium hydroxide]] (aqueous ammonia) causes the same precipitate to form. It then dissolves upon adding excess ammonia, to form a deep blue ammonia complex, tetraamminecopper(II).

Ionic equation:

:Cu(H<sub>2</sub>O)<sub>4</sub>(OH)<sub>2</sub>(s) + 4 NH<sub>3</sub>(aq) → [Cu(H<sub>2</sub>O)<sub>2</sub>(NH<sub>3</sub>)<sub>4</sub>]<sup>2+</sup>(aq) + 2H<sub>2</sub>O(l) + 2 OH<sup>−</sup>(aq)

A more delicate test than ammonia is [[potassium ferrocyanide]], which gives a brown precipitate with copper salts.

== Applications ==
[[Image:Native Copper Macro Digon3.jpg‎|thumb|right|225px|Native copper specimen (~ 4 cm in size)]]
[[Image:Cu pipe leonard.jpg|thumb|right|200px|Copper piping system with [[intumescent]] [[firestop]] being installed by an insulator in [[Vancouver]], [[Canada]]]]
Copper is [[malleable]] and [[ductile]], a good [[conductor of heat]] and, when very pure, a good [[conductor of electricity]].

The purity of copper is expressed as 4N for 99.99% pure or 7N for 99.99999% pure. The numeral gives the number of nines after the decimal point when expressed as a decimal (e.g. 4N means 0.9999, or 99.99%).

It is used extensively, in products such as:

=== [[Piping]] ===
* including [[water]] supply.

=== Electronics ===
* [[Copper wire]].
* [[Electromagnet]]s.
* [[Printed circuit board]]s.
* [[Lead]] free [[solder]], alloyed with [[tin]].
* [[Electrical machine]]s, especially electromagnetic motors, generators and transformers.
* Electrical [[relay]]s, electrical [[busbar]]s and electrical [[switch]]es.
* [[Vacuum tube]]s, [[cathode ray tube]]s, and the [[magnetron]]s in [[microwave oven]]s.
* [[Waveguide|Wave guide]]s for microwave radiation.
* [[Integrated circuit]]s, increasingly replacing [[aluminium]] because of its superior electrical conductivity.
* As a material in the manufacture of computer [[heat sink]]s, as a result of its superior heat dissipation capacity to [[aluminium]].

[[Image:Minneapolis City Hall.jpg|thumb|right|200px|Copper roof on the [[Minneapolis City Hall]], coated with [[Patina]]]]

=== Architecture / Industry ===
* Copper has been used as water-proof [[Metal roof|roofing]] material since ancient times, giving many old buildings their greenish roofs and domes. Initially [[copper oxide]] forms, replaced by [[Copper sulfide|cuprous and cupric sulfide]], and finally by [[Copper(II) carbonate|copper carbonate]]. The final [[carbonate]] [[patina]] is highly resistant to [[corrosion]].<ref>{{cite web | last = Berg | first = Jan | title = Why did we paint the library's roof? | url = http://www.deforest.lib.wi.us/FAQS.htm | accessdate = 2007-09-20}}</ref>
* [[Statue|Statuary]]: The [[Statue of Liberty]], for example, contains 179,220 pounds (81.3 [[tonne]]s) of copper.
* Alloyed with [[nickel]], e.g. [[cupronickel]] and [[Monel]], used as corrosive assistant materials in [[shipbuilding]].
* [[James Watt|Watt]]'s [[steam engine]] firebox due to superior heat dissipation.
* Copper [[nails]] were used in making [[oast]] [[cowl (oast)|cowls]].
* Copper compounds in liquid form are used as a preservative, particularly in treating original portion of structures during restoration of damage due to [[dry rot]].
* Copper wires may be placed over roofing materials to discourage the growth of [[moss]].
[[Image:CopperC.jpg|thumb|right|200px|Old copper utensils in a Jerusalem restaurant]]

=== Household products ===
* Copper [[plumbing]] fittings and compression tubes.
* Doorknobs and other fixtures in houses.
* [[Roofing]], guttering, and rainspouts on buildings.
* In [[cookware]], such as [[frying pan]]s.
* Most [[flatware]] ([[knife|knives]], [[fork]]s, [[spoon]]s) contains some copper ([[nickel silver]]).
* [[Sterling silver]], if it is to be used in dinnerware, must contain a few percent copper.
* Copper water heating cylinders
* Copper Range Hoods
* Copper Bath Tubs
* Copper Counters
* Copper Sinks

=== Coinage ===
* As a component of [[coin]]s, often as [[cupronickel]] alloy.
* Coins in the following countries all contain copper: European Union ([[Euro]]),<ref name=CDAUK>[http://www.cda.org.uk/news/euro.htm Copper Development Association, UK]</ref> United States,<ref name=US_mint>[http://www.usmint.gov/about_the_mint/index.cfm?action=coin_specifications US Mint specifications.]</ref> United Kingdom ([[Pound sterling|sterling]]),<ref name=Royal_mint>[http://www.royalmint.com/Corporate/BritishCoinage/Demonetisation.aspx Royal (i.e. United Kingdom) Mint specifications.]</ref> Australia<ref name=Royal_Aus_mint>[http://www.ramint.gov.au/making_coins/default.cfm?DefaultPage=coin_designs.cfm Royal Australian Mint specifications.]</ref> and New Zealand.<ref
name=The_Reserve_Bank_of_New_Zealand>[http://www.newcoins.govt.nz/1570749.html Change For The Better/Q & A/Technical Questions]</ref>
* [[Nickel (United States coin)|U.S. Nickels]] are 75.0% copper by weight and only 25.0% [[nickel]].<ref name=US_mint/>

=== Biomedical applications ===
* As a [[biostatic]] surface in hospitals, and to line parts of [[ship]]s to protect against [[barnacle]]s and [[mussel]]s, originally used pure, but superseded by [[Muntz Metal]]. [[Bacteria]] will not grow on a copper surface because it is biostatic. Copper [[doorknob]]s are used by [[hospital]]s to reduce the transfer of disease, and [[Legionellosis|Legionnaires' disease]] is suppressed by copper tubing in [[air-conditioning]] systems.
* [[Copper(II) sulfate]] is used as a [[fungicide]] and as algae control in domestic lakes and ponds. It is used in gardening powders and sprays to kill [[mildew]].
* [[Copper-62-PTSM]], a complex containing radioactive [[copper-62]], is used as a [[Positron emission tomography]] radiotracer for heart blood flow measurements.
* [[Copper-64]] can be used as a [[Positron emission tomography]] radiotracer for [[medical imaging]]. When complexed with a [[chelate]] it can be used to treat cancer through [[radiation therapy]].

=== Chemical applications ===
* Compounds, such as [[Fehling's solution]], have applications in chemistry.
* As a component in [[ceramic glaze]]s, and to color [[glass]].

=== Other ===
* [[Musical instrument]]s, especially [[brass instrument]]s and [[cymbals]].
* [[Class D Fire Extinguisher]], used in powder form to extinguish lithium fires by covering the burning metal and performing similar to a heat sink.
* Textile fibers to create [[antimicrobial]] protective fabrics.<ref> [http://www.cupron.com Cupron Antimicrobial]</ref>
* Small arms [[Cartridge (firearms) | ammunition]] commonly uses copper as a jacketing material around the bullet core. Copper is also commonly used as a case material, in the form of brass.

== Biological role ==
[[Image:ARS copper rich foods.jpg|right|thumb|Rich sources of [[copper]] include oysters, beef or lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper. Good sources include lobster, nuts and sunflower seeds, green olives, avocados and wheat bran.]]
Copper is essential in all plants and animals. Copper is carried mostly in the bloodstream on a [[plasma protein]] called [[ceruloplasmin]]. When copper is first absorbed in the gut it is transported to the [[liver]] bound to [[serum albumin|albumin]]. Copper is found in a variety of [[enzyme]]s, including the copper centers of [[cytochrome c oxidase]] and the enzyme [[superoxide dismutase]] (containing copper and zinc). In addition to its enzymatic roles, copper is used for biological electron transport. The blue copper proteins that participate in electron transport include [[azurin]] and [[plastocyanin]]. The name "blue copper" comes from their intense blue color arising from a ligand-to-metal charge transfer (LMCT) absorption band around 600&nbsp;nm.

Most [[mollusc]]s and some [[arthropod]]s such as the [[horseshoe crab]] use the copper-containing pigment [[hemocyanin]] rather than [[iron]]-containing [[hemoglobin]] for oxygen transport, so their blood is blue when oxygenated rather than red.<ref name=NOAA>[http://www.ocean.udel.edu/horseshoecrab/funFacts.html ''Horseshoe Crab Fun Facts''] NOAA and Univ. of Delaware</ref>

It is believed that [[zinc]] and copper compete for absorption in the digestive tract so that a diet that is excessive in one of these minerals may result in a deficiency in the other. The [[Recommended Dietary Allowance|RDA]] for copper in normal healthy adults is 0.9 [[milligram|mg]]/day. On the other hand, professional research on the subject recommends 3.0 [[milligram|mg]]/day.<ref>National Research Council. Copper. In: Recommended Dietary Allowances. Washington, D.C.: Food Nutrition Board, NRC/NAS, 1980: 151-154.</ref> Because of its role in facilitating iron uptake, [[copper deficiency]] can often produce [[anemia]]-like symptoms. In humans, the symptoms of [[Wilson's disease]] are caused by an accumulation of copper in body tissues.

Chronic copper depletion leads to abnormalities in metabolism of fats, high triglycerides, non-alkoholic steatohepatitis (NASH), fatty liver disease and poor melanin and dopamine sythesis causing depression and sun-burns. Food rich in copper should be eaten away from any milk or egg proteins as they block absorption.

=== Toxicity ===
{{Unreferenced|date=March 2008}}
{{Expand|date=March 2008}}
Thirty grams of [[copper sulfate]] is potentially [[lethal]] in humans{{Fact|date=March 2008}}{{Dubious|date=March 2008}}. The suggested safe level of copper in [[drinking water]] for humans varies depending on the source, but tends to be pegged at 1.5 to 2&nbsp;mg/L{{Fact|date=March 2008}}. The [[Dietary Reference Intake|DRI]] Tolerable Upper Intake Level for adults of dietary copper from all sources is 10 mg/day{{Fact|date=March 2008}}. In toxicity, copper can inhibit the [[enzyme]] [[dihydrophil hydratase]], an enzyme involved in [[haemopoiesis]]{{Facts|date=November 2007}}.

Symptoms of copper [[poison]]ing are very similar to those produced by [[arsenic]]. Fatal cases are generally terminated by convulsions, palsy, and insensibility.{{Facts|date=November 2007}}

In cases of suspected copper poisoning, [[Ovalbumin]] is to be administered in either of its forms which can be most readily obtained, as milk or [[egg white|whites of eggs]]. Vinegar should not be given. The inflammatory symptoms are to be treated on general principles, and so are the nervous.{{Facts|date=November 2007}}

A significant portion of the toxicity of copper comes from its ability to accept and donate single electrons as it changes oxidation state. This catalyzes the production of very reactive radical ions such as [[hydroxyl radical]] in a manner similar to [[Fenton's reagent|Fenton chemistry]].<ref name=PubMed>{{cite journal |url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8619019&dopt=Abstract |journal=Radiat Res. |author=Held KD ''et al.'' |date=May 1996 |volume=145 |issue=5 |pages=542–53 |title=Role of Fenton chemistry in thiol-induced toxicity and apoptosis |doi=10.2307/3579272}}</ref> This catalytic activity of copper is used by the enzymes that it is associated with and is thus only toxic when unsequestered and unmediated. This increase in unmediated reactive radicals is generally termed [[oxidative stress]] and is an active area of research in a variety of diseases where copper may play an important but more subtle role than in acute toxicity.

An inherited condition called [[Wilson's disease]] causes the body to retain copper, since it is not excreted by the [[liver]] into the [[bile]]. This disease, if untreated, can lead to [[brain]] and [[liver]] damage. In addition, studies have found that people with mental illnesses such as [[schizophrenia]] had heightened levels of copper in their systems. However it is unknown at this stage whether the copper contributes to the mental illness, whether the body attempts to store more copper in response to the illness, or whether the high levels of copper are the result of the mental illness.{{Facts|date=November 2007}}

Too much copper in water has also been found to damage marine life. The observed effect of these higher concentrations on fish and other creatures is damage to gills, liver, kidneys, and the nervous system. It also interferes with the sense of smell in fish, thus preventing them from choosing good mates or finding their way to mating areas.{{Facts|date=November 2007}}

=== Miscellaneous hazards ===
The metal, when powdered, is a [[fire hazard]]. At concentrations higher than 1 mg/L, copper can stain clothes and items washed in water.

==See also==
*[[Acierage]]
*[[Anaconda Copper]]
*[[Antofagasta PLC]]
*[[Codelco]]
*[[Cold Water Pitting of Copper Tube]]
*[[Copper extraction techniques]]
*[[Erosion Corrosion of Copper Water Tubes]]
*[[Metal theft]]
*[[Native Copper]]
*[[Operation Tremor]]
*[[Peak copper]]
*[[Smelter]]

==References==
{{reflist}}

==Further reading==
*{{cite web |title=''Copper: Technology & Competitiveness (Summary)'' Chapter 6: Copper Production Technology |publisher=Office of Technology Assessment |year=2005 |url=http://www.wws.princeton.edu/ota/ns20/alpha_f.html}}
*Current Medicinal Chemistry, Volume 12, Number 10, May 2005, pp. 1161-1208(48) Metals, Toxicity and Oxidative Stress
*{{cite book |title=Materials Science and Engineering: an Introduction, 6th Ed. |author=William D. Callister |publisher=Wiley, New York |year=2003 |isbn=0471736961 |location=Table 6.1 p137. }}
*[http://www.memsnet.org/material/coppercubulk/ Material: Copper (Cu), bulk], MEMS and Nanotechnology Clearinghouse.
*{{cite journal |author=Kim BE, Nevitt T, Thiele DJ |title=Mechanisms for copper acquisition, distribution and regulation |journal=[[Nat. Chem. Biol.]] |volume=4 |issue=3 |pages=176–85 |year=2008 |pmid=18277979 |doi=10.1038/nchembio.72 |url=http://www.nature.com/nchembio/journal/v4/n3/abs/nchembio.72.html}}

==External links==
{{Commons|Copper}}
{{wiktionary|copper}}
*[http://www.npi.gov.au/database/substance-info/profiles/27.html National Pollutant Inventory - Copper and compounds fact sheet]
*[http://www.weldaloy.com/resource_center.php Copper Resource Page.] Includes 12 PDF files detailing the material properties of various kinds of copper, as well as various guides and tools for the copper industry.
*[http://www.copper.org The Copper Development Association] has an extensive site of properties and uses of copper; it also maintains a [http://www.brass.org web site dedicated to [[brass]], a copper alloy].
* [http://www.3rd1000.com/elements/Copper.htm The Third Millennium Online page on Copper]
* [http://www.webelements.com/webelements/elements/text/Cu/index.html The WebElements page on Copper]
*[http://www.pniok.de/cu.htm Picture in the Element collection from Heinrich Pniok]

{{clear}}
{{compact periodic table}}

[[Category:Copper| ]]
[[Category:Chemical elements]]
[[Category:Dietary minerals]]
[[Category:Electrical conductors]]
[[Category:Noble metals]]
[[Category:Recyclable materials]]
[[Category:Symbols of Utah]]
[[Category:Transition metals]]

[[af:Koper]]
[[ar:نحاس]]
[[ay:Anti]]
[[az:Mis]]
[[bn:তামা]]
[[zh-min-nan:Cu (goân-sò͘)]]
[[be:Медзь]]
[[be-x-old:Медзь]]
[[bs:Bakar]]
[[bg:Мед (елемент)]]
[[ca:Coure]]
[[cv:Пăхăр]]
[[cs:Měď]]
[[co:Ramu]]
[[cy:Copr]]
[[da:Kobber]]
[[de:Kupfer]]
[[et:Vask]]
[[el:Χαλκός]]
[[es:Cobre]]
[[eo:Kupro]]
[[eu:Kobre]]
[[fa:مس]]
[[fr:Cuivre]]
[[fur:Ram]]
[[ga:Copar]]
[[gv:Cobbyr]]
[[gd:Copar]]
[[gl:Cobre]]
[[gu:તાંબુ]]
[[ko:구리]]
[[hy:Պղինձ]]
[[hi:ताम्र]]
[[hr:Bakar (element)]]
[[io:Kupro]]
[[id:Tembaga]]
[[is:Kopar]]
[[it:Rame]]
[[he:נחושת]]
[[ka:სპილენძი]]
[[kw:Kober]]
[[sw:Shaba]]
[[kg:Mutako]]
[[ht:Kuiv]]
[[ku:Mis]]
[[la:Cuprum]]
[[lv:Varš]]
[[lb:Koffer]]
[[lt:Varis]]
[[li:Koper]]
[[jbo:tunka]]
[[hu:Réz]]
[[mk:Бакар]]
[[ml:ചെമ്പ്]]
[[mi:Konukura]]
[[mr:तांबे]]
[[ms:Tembaga]]
[[mn:Зэс]]
[[nah:Chīltic tepoztli]]
[[nl:Koper (element)]]
[[ja:銅]]
[[no:Kobber]]
[[nn:Kopar]]
[[oc:Coire]]
[[uz:Mis]]
[[nds:Kopper (Metall)]]
[[pl:Miedź]]
[[pt:Cobre]]
[[ksh:Koffer (Metall)]]
[[ro:Cupru]]
[[qu:Anta]]
[[ru:Медь]]
[[sa:ताम्रम्]]
[[sq:Bakri]]
[[scn:Rami]]
[[simple:Copper]]
[[sk:Meď]]
[[sl:Baker]]
[[sr:Бакар]]
[[sh:Bakar]]
[[fi:Kupari]]
[[sv:Koppar]]
[[tl:Tanso]]
[[ta:செப்பு]]
[[te:రాగి]]
[[th:ทองแดง]]
[[vi:Đồng (nguyên tố)]]
[[tg:Мис]]
[[tr:Bakır]]
[[uk:Мідь]]
[[ur:تانبا]]
[[yi:קופער]]
[[zh-yue:銅]]
[[zh:铜]]

Revision as of 15:08, 22 May 2008

Copper, 29Cu
Native copper (~4 cm in size)
Copper
AppearanceRed-orange metallic luster
Standard atomic weight Ar°(Cu)
Copper in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Cu

Ag
nickelcopperzinc
Atomic number (Z)29
Groupgroup 11
Periodperiod 4
Block  d-block
Electron configuration[Ar] 3d10 4s1
Electrons per shell2, 8, 18, 1
Physical properties
Phase at STPsolid
Melting point1357.77 K ​(1084.62 °C, ​1984.32 °F)
Boiling point2835 K ​(2562 °C, ​4643 °F)
Density (at 20° C)8.935 g/cm3[3]
when liquid (at m.p.)8.02 g/cm3
Heat of fusion13.26 kJ/mol
Heat of vaporization300.4 kJ/mol
Molar heat capacity24.440 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1509 1661 1850 2089 2404 2834
Atomic properties
Oxidation statescommon: +2
−2,? 0,[4] +1,[5] +3,[5] +4[5]
ElectronegativityPauling scale: 1.90
Ionization energies
  • 1st: 745.5 kJ/mol
  • 2nd: 1957.9 kJ/mol
  • 3rd: 3555 kJ/mol
  • (more)
Atomic radiusempirical: 128 pm
Covalent radius132±4 pm
Van der Waals radius140 pm
Color lines in a spectral range
Spectral lines of copper
Other properties
Natural occurrenceprimordial
Crystal structureface-centered cubic (fcc) (cF4)
Lattice constant
Face-centered cubic crystal structure for copper
a = 361.50 pm (at 20 °C)[3]
Thermal expansion16.64×10−6/K (at 20 °C)[3]
Thermal conductivity401 W/(m⋅K)
Electrical resistivity16.78 nΩ⋅m (at 20 °C)
Magnetic orderingdiamagnetic[6]
Molar magnetic susceptibility−5.46×10−6 cm3/mol[7]
Young's modulus110–128 GPa
Shear modulus48 GPa
Bulk modulus140 GPa
Speed of sound thin rod(annealed)
3810 m/s (at r.t.)
Poisson ratio0.34
Mohs hardness3.0
Vickers hardness343–369 MPa
Brinell hardness235–878 MPa
CAS Number7440-50-8
History
Namingafter Cyprus, principal mining place in Roman era (Cyprium)
DiscoveryMiddle East (9000 BC)
Symbol"Cu": from Latin cuprum
Isotopes of copper
Main isotopes[8] Decay
abun­dance half-life (t1/2) mode pro­duct
63Cu 69.2% stable
64Cu synth 12.70 h β+ 64Ni
β 64Zn
65Cu 30.9% stable
67Cu synth 61.83 h β 67Zn
 Category: Copper
| references

Copper (Template:PronEng) is a chemical element with the symbol Cu (Template:Lang-la) and atomic number 29. It is a ductile metal with excellent electrical conductivity and is rather soft in its pure state and has a pinkish luster which is (beside gold) unusual for metals which are normally silvery white. It finds extensive use as an electrical conductor, heat conductor, as a building material, and as a component of various alloys.

Copper is an essential trace nutrient to all high plants and animals. In animals, including humans, it is found primarily in the bloodstream, as a co-factor in various enzymes, and in copper-based pigments. However, in sufficient amounts, copper can be poisonous and even fatal to organisms.

Copper has played a significant part in the history of humankind, which has used the easily accessible uncompounded metal for thousands of years. Several early civilizations have early evidence of using copper. During the Roman Empire, copper was principally mined on Cyprus, hence the origin of the name of the metal as Cyprium, "metal of Cyprus", later shortened to Cuprum.

A number of countries, such as Chile and the United States, still have sizable reserves of the metal which are extracted through large open pit mines, however like tin there may be insufficient reserves to sustain current rates of consumption.[9] High demand relative to supply has caused a price spike in the 2000s[citation needed].

Copper also has a significant presence as a decorative metal art. It can also be used as an anti-germ surface that can add to the anti-bacterial and antimicrobial features of buildings such as hospitals. [10]

History

Copper, as native copper, is one of the few metals to naturally occur as an uncompounded mineral. Copper was known to some of the oldest civilizations on record, and has a history of use that is at least 10,000 years old. No one knows exactly when copper was first discovered, but earliest estimates place this event around 9000 BC.[11] A copper pendant was found in what is now northern Iraq that dates to 8700 BC. By 5000 BC, there are signs of copper smelting: the refining of copper from simple copper compounds such as malachite or azurite. Among archaeological sites in Anatolia, Çatal Höyük (~6000 BC) features native copper artifacts and smelted lead beads, but no smelted copper. But Can Hasan (~5000 BC) had access to smelted copper; this site has yielded the oldest known cast copper artifact, a copper mace head.

Ancient Copper ingot from Zakros, Crete is shaped in the form of an animal skin typical for that era.

Copper smelting appears to have been developed independently in several parts of the world. In addition to its development in Anatolia by 5000 BC, it was developed in China before 2800 BC, in the Andes around 2000 BC, in Central America around 600 AD, and in West Africa around 900 AD.[12] Copper is found extensively in the Indus Valley Civilization by the 3rd millennium BC.[13] In Europe, Ötzi the Iceman, a well-preserved male dated to 3300-3200 BC, was found with an axe tipped with copper that was 99.7% pure. High levels of arsenic in his hair suggest he was involved in copper smelting.

There exist copper and bronze artifacts from Sumerian cities that date to 3000 BC, and Egyptian artifacts of copper and copper-tin alloys nearly as old. In one pyramid, a copper plumbing system was found that is 5000 years old. The Egyptians found that adding a small amount of tin made the metal easier to cast, so copper-tin (bronze) alloys were found in Egypt almost as soon as copper was found. Very important sources of copper in the Levant were located in Timna valley (Palestine) and Faynan (biblical Punon, Jordan).[14]

In the Americas production in the Old Copper Complex, located in present day Michigan and Wisconsin, was dated back to between 6000 to 3000 BC.[15]

By 2000 BC, Europe was using bronze. The use of bronze became so pervasive in a certain era of civilization (approximately 2500 BC to 600 BC in Europe) that it has been named the Bronze Age. The transitional period in certain regions between the preceding Neolithic period and the Bronze Age is termed the Chalcolithic ("copper-stone"), with some high-purity copper tools being used alongside stone tools. Brass (copper-zinc) was known to the Greeks, but only became a significant supplement to bronze during the Roman empire.

In alchemy the symbol for copper, perhaps a stylized mirror, was also the symbol for the goddess and planet Venus.

In Greek the metal was known by the name chalkos (χαλκός). Copper was a very important resource for the Romans, Greeks and other ancient peoples. In Roman times, it became known as aes Cyprium (aes being the generic Latin term for copper alloys such as bronze and other metals, and Cyprium because so much of it was mined in Cyprus). From this, the phrase was simplified to cuprum and then eventually Anglicized into the English copper. Copper was associated with the goddess Aphrodite/Venus in mythology and alchemy, owing to its lustrous beauty, its ancient use in producing mirrors, and its association with Cyprus, which was sacred to the goddess.

British Isles

West Mine at Alderley Edge

During the Bronze Age, copper was mined in the British Isles mainly in the following locations:

At Great Orme in North Wales, such working extended for a depth of 70 metres.[16] At Alderley Edge in Cheshire, carbon dates have established mining at around 2280 to 1890 BC (at 95% probability).[17]

United States

Miners at the Tamarack Mine in Copper Country, Michigan, USA in 1905.

Copper mining in the United States began with marginal workings by Native Americans and some development by early Spaniards. Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600. Europeans were mining copper in Connecticut as early as 1709. Perhaps the oldest operating large-scale copper mine was the historic Elizabeth Mine in Vermont. Dating to the 1700s, "the Liz" produced copper until it was closed in 1958. Westward movement also brought an expansion of copper exploitation with developments of significant deposits in Michigan and Arizona during the 1850s and then in Montana during the 1860s.

Native copper was mined extensively in Michigan's Keweenaw Peninsula with the heart of extraction at the productive Calumet and Hecla Mining Company. Arizona had many notable deposits including the Copper Queen in Bisbee and the United Verde in Jerome. The Anaconda in Butte, Montana became the nation's chief copper supplier by 1886.

Copper is mined in many other areas of the United States, including Utah, Nevada and Tennessee. Copper is the state mineral for Utah.

Isotopes

There are two stable isotopes, 63Cu and 65Cu, along with a couple dozen radioisotopes. The vast majority of radioisotopes have half lives on the order of minutes or less; the longest lived, 67Cu, has a half life of 61.8 hours. See also isotopes of copper.

Notable characteristics

File:029-Cu.jpg
Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color.
Copper exists as a metallically bonded substance, allowing it to have a wide variety of metallic properties.

Copper is a reddish-colored metal; it has its characteristic color because of its band structure. In its liquefied state, a pure copper surface without ambient light appears somewhat greenish, a characteristic shared with gold. When liquid copper is in bright ambient light, it retains some of its pinkish luster.

Copper occupies the same family of the periodic table as silver and gold, since they each have one s-orbital electron on top of a filled electron shell. This similarity in electron structure makes them similar in many characteristics. All have very high thermal and electrical conductivity, and all are malleable metals.

Conductivity

Copper has a high electrical and thermal conductivity, second only to silver among pure metals at room temperature.[18]

Corrosion

Pure water and air
Copper is a metal that does not react with water (H2O), but the oxygen of the air will react slowly at room temperature to form a layer of brown-black copper oxide on copper metal.

The Pourbaix diagram for copper in pure water, perchloric acid or sodium It can be seen that copper in "pure" water is more noble than hydrogen. As a result it does not corrode in oxygen free water and the corrosion rate in oxygenated water is low. hydroxide[19]

It is important to note that in contrast to the oxidation of iron by wet air that the layer formed by the reaction of air with copper has a protective effect against further corrosion. On old copper roofs a green layer of copper carbonate, called verdigris or patina, can often be seen. Another notable example of this is on the Statue of Liberty.

Sulfide media

Copper metal does react with hydrogen sulfide- and sulfide-containing solutions. A series of different copper sulfides can form on the surface of the copper metal.

The Pourbaix diagram for copper in a sulfide containing aqueous medium[19]

Note that the copper sulfide area of the plot is very complex due to the existence of many different sulfides, a close up is also provided to make the graph more clear. It is clear that the copper is now able to corrode even without the need for oxygen as the copper is now less noble than hydrogen. This can be observed in every day life when copper metal surfaces tarnish after exposure to air which contains sulfur compounds.

File:Close up of copper sulphide pourbiax diagram.png
The Pourbaix diagram for copper in a sulfide containing aqueous medium[19]

Ammonia media

Copper does react with oxygen-containing ammonia solutions because the ammonia forms water-soluble copper complexes. The formation of these complexes causes the corrosion to become more thermodynamically favored than the corrosion of copper in an identical solution that does not contain the ammonia.

The Pourbaix diagram for copper in 10 M ammonia solution[19]

Chloride media

Copper does react with a combination of oxygen and hydrochloric acid to form a series of copper chlorides. It is interesting to note that if copper(II) chloride (green/blue) is boiled with copper metal (with little or no oxygen present) then white copper(I) chloride will be formed.

The Pourbaix diagram for copper in a chloride solution[19]

Mechanical properties

A single crystal copper consists of a few micrometres of small crystals. In this form of crystal (c), the yield stress is high and crystal undergoes a large amount of elastic deformation before going into the plastic deformation region. The plastic deformation region has an unpredictable outcome. The stress level decreases significantly as necking begins to occur.

Polycrystal copper has many crystal of different geometries combined. The plastic deformation of polycrystal is similar to mild steel. Copper has a high ductility and will continue to elongate as stress is applied. It is very useful in copper wire drawing.

Numerous copper alloys exist, many with important historical and contemporary uses. Speculum metal and bronze are alloys of copper and tin. Brass is an alloy of copper and zinc. Monel metal, also called cupronickel, is an alloy of copper and nickel. While the metal "bronze" usually refers to copper-tin alloys, it also is a generic term for any alloy of copper, such as aluminium bronze, silicon bronze, and manganese bronze.

Germicidal effect

Copper is germicidal, via the oligodynamic effect. For example, brass doorknobs disinfect themselves of many bacteria within a period of eight hours.[20] Antimicrobial properties of copper are effective against MRSA,[21] Escherichia coli[22] and other pathogens.[23][24][25] In colder temperature, longer time is required to kill bacteria.

Occurrence and modern industry

Chuquicamata (Chile). One of the largest open pit copper mines in the world.
Copper output in 2005
World production trend
Evolution of the historical copper price
source : minerals.usgs.gov (XLS)
Current price is at least four times higher than the 2002 value.
File:Coppernuggets.jpg
Native Copper Placer Nuggets
Native copper

In 2005, Chile was the top mine producer of copper with at least one-third world share followed by the USA, Indonesia and Peru, reports the British Geological Survey.

Copper can be found as native copper in mineral form. Minerals such as the sulfides: chalcopyrite (CuFeS2), bornite (Cu5FeS4), covellite (CuS), chalcocite (Cu2S) are sources of copper, as are the carbonates: azurite (Cu3(CO3)2(OH)2) and malachite (Cu2CO3(OH)2) and the oxide: cuprite (Cu2O).

Most copper ore is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0 percent copper. Examples include: Chuquicamata in Chile and El Chino Mine in New Mexico. The average abundance of copper found within crustal rocks is approximately 68 ppm by mass, and 22 ppm by atoms.

The Intergovernmental Council of Copper Exporting Countries (CIPEC), defunct since 1992, once tried to play a similar role for copper as OPEC does for oil, but never achieved the same influence, not least because the second-largest producer, the United States, was never a member. Formed in 1967, its principal members were Chile, Peru, Zaire, and Zambia.

The copper price has quintupled from the 60-year low in 1999, rising from US$0.60 per pound (US$1.32/kg) in June 1999 to US$3.75 per pound (US$8.27/kg) in May 2006, where it dropped to US$2.40 (US$5.29/kg) in February 2007 then rebounded to US$3.50 (US$7.71/kg = £3.89 = 5.00) in April 2007.[26]

The Earth has an estimated 61 years of copper reserves remaining.[27] Environmental analyst, Lester Brown, however, has suggested copper might run out within 25 years based on a reasonable extrapolation of 2% growth per year.[28]

Copper has been in use at least 10,000 years, but more than 95 percent of all copper ever mined and smelted has been extracted since 1900. And as India and China race to catch up with the West, copper supplies are getting tight.[29] Copper is among the most important industrial metals. Like fossil fuels, copper is a finite resource. Peak copper is the point in time at which the maximum global copper production rate is reached, according to Hubbert peak theory, the rate of production enters its terminal decline.

Compounds

Common oxidation states of copper include the less stable copper(I) state, Cu+; and the more stable copper(II) state, Cu2+, which forms blue or blue-green salts and solutions. Under unusual conditions, a 3+ state and even an extremely rare 4+ state can be obtained. Using old nomenclature for the naming of salts, copper(I) is called cuprous, and copper(II) is cupric. In oxidation copper is mildly basic.

Copper(II) carbonate is green from which arises the unique appearance of copper-clad roofs or domes on some buildings. Copper(II) sulfate forms a blue crystalline pentahydrate which is perhaps the most familiar copper compound in the laboratory. It is used as a fungicide, known as Bordeaux mixture.

There are two stable copper oxides, copper(II) oxide (CuO) and copper(I) oxide (Cu2O). Copper oxides are used to make yttrium barium copper oxide (YBa2Cu3O7-δ) or YBCO which forms the basis of many unconventional superconductors.

Tests for copper(II) ion

Add aqueous sodium hydroxide. A blue precipitate of copper(II) hydroxide should form.

Ionic equation:

Cu2+(aq) + 2OH(aq) → Cu(OH)2(s)

The full equation shows that the reaction is due to hydroxide ions deprotonating the hexaaquacopper (II) complex:

[Cu(H2O)6]2+(aq) + 2 OH(aq) → Cu(H2O)4(OH)2(s) + 2 H2O (l)

Adding ammonium hydroxide (aqueous ammonia) causes the same precipitate to form. It then dissolves upon adding excess ammonia, to form a deep blue ammonia complex, tetraamminecopper(II).

Ionic equation:

Cu(H2O)4(OH)2(s) + 4 NH3(aq) → [Cu(H2O)2(NH3)4]2+(aq) + 2H2O(l) + 2 OH(aq)

A more delicate test than ammonia is potassium ferrocyanide, which gives a brown precipitate with copper salts.

Applications

Native copper specimen (~ 4 cm in size)
Copper piping system with intumescent firestop being installed by an insulator in Vancouver, Canada

Copper is malleable and ductile, a good conductor of heat and, when very pure, a good conductor of electricity.

The purity of copper is expressed as 4N for 99.99% pure or 7N for 99.99999% pure. The numeral gives the number of nines after the decimal point when expressed as a decimal (e.g. 4N means 0.9999, or 99.99%).

It is used extensively, in products such as:

Electronics

Copper roof on the Minneapolis City Hall, coated with Patina

Architecture / Industry

File:CopperC.jpg
Old copper utensils in a Jerusalem restaurant

Household products

Coinage

Biomedical applications

Chemical applications

Other

Biological role

Rich sources of copper include oysters, beef or lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper. Good sources include lobster, nuts and sunflower seeds, green olives, avocados and wheat bran.

Copper is essential in all plants and animals. Copper is carried mostly in the bloodstream on a plasma protein called ceruloplasmin. When copper is first absorbed in the gut it is transported to the liver bound to albumin. Copper is found in a variety of enzymes, including the copper centers of cytochrome c oxidase and the enzyme superoxide dismutase (containing copper and zinc). In addition to its enzymatic roles, copper is used for biological electron transport. The blue copper proteins that participate in electron transport include azurin and plastocyanin. The name "blue copper" comes from their intense blue color arising from a ligand-to-metal charge transfer (LMCT) absorption band around 600 nm.

Most molluscs and some arthropods such as the horseshoe crab use the copper-containing pigment hemocyanin rather than iron-containing hemoglobin for oxygen transport, so their blood is blue when oxygenated rather than red.[37]

It is believed that zinc and copper compete for absorption in the digestive tract so that a diet that is excessive in one of these minerals may result in a deficiency in the other. The RDA for copper in normal healthy adults is 0.9 mg/day. On the other hand, professional research on the subject recommends 3.0 mg/day.[38] Because of its role in facilitating iron uptake, copper deficiency can often produce anemia-like symptoms. In humans, the symptoms of Wilson's disease are caused by an accumulation of copper in body tissues.

Chronic copper depletion leads to abnormalities in metabolism of fats, high triglycerides, non-alkoholic steatohepatitis (NASH), fatty liver disease and poor melanin and dopamine sythesis causing depression and sun-burns. Food rich in copper should be eaten away from any milk or egg proteins as they block absorption.

Toxicity

Thirty grams of copper sulfate is potentially lethal in humans[citation needed][dubiousdiscuss]. The suggested safe level of copper in drinking water for humans varies depending on the source, but tends to be pegged at 1.5 to 2 mg/L[citation needed]. The DRI Tolerable Upper Intake Level for adults of dietary copper from all sources is 10 mg/day[citation needed]. In toxicity, copper can inhibit the enzyme dihydrophil hydratase, an enzyme involved in haemopoiesis[citation needed].

Symptoms of copper poisoning are very similar to those produced by arsenic. Fatal cases are generally terminated by convulsions, palsy, and insensibility.[citation needed]

In cases of suspected copper poisoning, Ovalbumin is to be administered in either of its forms which can be most readily obtained, as milk or whites of eggs. Vinegar should not be given. The inflammatory symptoms are to be treated on general principles, and so are the nervous.[citation needed]

A significant portion of the toxicity of copper comes from its ability to accept and donate single electrons as it changes oxidation state. This catalyzes the production of very reactive radical ions such as hydroxyl radical in a manner similar to Fenton chemistry.[39] This catalytic activity of copper is used by the enzymes that it is associated with and is thus only toxic when unsequestered and unmediated. This increase in unmediated reactive radicals is generally termed oxidative stress and is an active area of research in a variety of diseases where copper may play an important but more subtle role than in acute toxicity.

An inherited condition called Wilson's disease causes the body to retain copper, since it is not excreted by the liver into the bile. This disease, if untreated, can lead to brain and liver damage. In addition, studies have found that people with mental illnesses such as schizophrenia had heightened levels of copper in their systems. However it is unknown at this stage whether the copper contributes to the mental illness, whether the body attempts to store more copper in response to the illness, or whether the high levels of copper are the result of the mental illness.[citation needed]

Too much copper in water has also been found to damage marine life. The observed effect of these higher concentrations on fish and other creatures is damage to gills, liver, kidneys, and the nervous system. It also interferes with the sense of smell in fish, thus preventing them from choosing good mates or finding their way to mating areas.[citation needed]

Miscellaneous hazards

The metal, when powdered, is a fire hazard. At concentrations higher than 1 mg/L, copper can stain clothes and items washed in water.

See also

References

  1. ^ "Standard Atomic Weights: Copper". CIAAW. 1969.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ a b c Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  4. ^ Moret, Marc-Etienne; Zhang, Limei; Peters, Jonas C. (2013). "A Polar Copper–Boron One-Electron σ-Bond". J. Am. Chem. Soc. 135 (10): 3792–3795. doi:10.1021/ja4006578. PMID 23418750.
  5. ^ a b c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  6. ^ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5. Archived from the original (PDF) on 2011-03-03.
  7. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  8. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  9. ^ "Earth's Limited Supply of Metals Raises Concern". Retrieved 2008-03-16.
  10. ^ Barnaby J. Feder (March 26, 2008). "Regulators Stamp Copper as a Germ Killer". New York Times. {{cite news}}: Check date values in: |date= (help)
  11. ^ http://www.csa.com/discoveryguides/copper/overview.php
  12. ^ Richard Cowen, Essays on Geology, History, and People, Chapter 3: "Fire and Metals: Copper".
  13. ^ harappa.com (Web archive)
  14. ^ J.M. Tebes "A Land whose Stones are Iron, and out of whose Hills You can Dig Copper": The Exploitation and Circulation of Copper in the Iron Age Negev and Edom, DavarLogos 6/1 (2007)]
  15. ^ Thomas C. Pleger, Ph.D. (2000). "The Old Copper Complex of the Western Great Lakes". UW-Fox Valley Anthropology. Retrieved 2007-08-15.
  16. ^ O’Brien, W. (1997). Bronze Age Copper Mining in Britain and Ireland. Shire Publications Ltd. ISBN 0747803218.
  17. ^ Timberlake and Prag, 2005
  18. ^ Los Alamos National Laboratory - Copper
  19. ^ a b c d e Ignasi Puigdomenech, Hydra/Medusa Chemical Equilibrium Database and Plotting Software (2004) KTH Royal Institute of Technology, freely downloadable software at [1]
  20. ^ Phyllis J. Kuhn, Ph.D. (1983). "Doorknobs: A Source of Nosocomial Infection?". Retrieved 2007-08-15.
  21. ^ Noyce JO, Michels H, Keevil CW (2006). "Potential use of copper surfaces to reduce survival of epidemic meticillin-resistant Staphylococcus aureus in the healthcare environment". J. Hosp. Infect. 63 (3): 289–97. doi:10.1016/j.jhin.2005.12.008. PMID 16650507.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  22. ^ Noyce JO, Michels H, Keevil CW (2006). "Use of copper cast alloys to control Escherichia coli O157 cross-contamination during food processing". Appl. Environ. Microbiol. 72 (6): 4239–44. doi:10.1128/AEM.02532-05. PMID 16751537.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  23. ^ Mehtar S, Wiid I, Todorov SD (2008). "The antimicrobial activity of copper and copper alloys against nosocomial pathogens and Mycobacterium tuberculosis isolated from healthcare facilities in the Western Cape: an in-vitro study". J. Hosp. Infect. 68 (1): 45–51. doi:10.1016/j.jhin.2007.10.009. PMID 18069086.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  24. ^ Gant VA, Wren MW, Rollins MS, Jeanes A, Hickok SS, Hall TJ (2007). "Three novel highly charged copper-based biocides: safety and efficacy against healthcare-associated organisms". J. Antimicrob. Chemother. 60 (2): 294–9. doi:10.1093/jac/dkm201. PMID 17567632.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  25. ^ Noyce JO, Michels H, Keevil CW (2007). "Inactivation of influenza A virus on copper versus stainless steel surfaces". Appl. Environ. Microbiol. 73 (8): 2748–50. doi:10.1128/AEM.01139-06. PMID 17259354.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  26. ^ Copper Trends: Live Metal Spot Prices, MetalSpotPrice.com
  27. ^ New Scientist. May 26, 2007.
  28. ^ Brown, Lester (2006). Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble. New York: W.W. Norton. p. 109. ISBN 0393328317.
  29. ^ Andrew Leonard (2006-03-02). "Peak copper?". Salon - How the World Works. Retrieved 2008-03-23.
  30. ^ Berg, Jan. "Why did we paint the library's roof?". Retrieved 2007-09-20.
  31. ^ Copper Development Association, UK
  32. ^ a b US Mint specifications.
  33. ^ Royal (i.e. United Kingdom) Mint specifications.
  34. ^ Royal Australian Mint specifications.
  35. ^ Change For The Better/Q & A/Technical Questions
  36. ^ Cupron Antimicrobial
  37. ^ Horseshoe Crab Fun Facts NOAA and Univ. of Delaware
  38. ^ National Research Council. Copper. In: Recommended Dietary Allowances. Washington, D.C.: Food Nutrition Board, NRC/NAS, 1980: 151-154.
  39. ^ Held KD; et al. (May 1996). "Role of Fenton chemistry in thiol-induced toxicity and apoptosis". Radiat Res. 145 (5): 542–53. doi:10.2307/3579272. {{cite journal}}: Explicit use of et al. in: |author= (help)

Further reading