Copper is a
chemical element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
with the
symbol
A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...
Cu (from la, cuprum) and
atomic number 29. It is a soft, malleable, and
ductile metal with very high
thermal and
electrical conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...
. A freshly exposed surface of pure copper has a
pinkish-orange color. Copper is used as a conductor of heat and electricity, as a
building material, and as a constituent of various metal
alloys, such as
sterling silver used in
jewelry,
cupronickel used to make marine hardware and
coins, and
constantan
Constantan is a proprietary name for a copper–nickel alloy also known as Eureka, Advance, and Ferry. It usually consists of 55% copper and 45% nickel. Its main feature is the low thermal variation of its resistivity, which is constant ...
used in
strain gauge
A strain gauge (also spelled strain gage) is a device used to measure strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports ...
s and
thermocouples for temperature measurement.
Copper is one of the few metals that can occur in nature in a directly usable metallic form (
native metal
A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, m ...
s). This led to very early human use in several regions, from circa 8000 BC. Thousands of years later, it was the first metal to be
smelted from sulfide ores, circa 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal,
tin, to create
bronze
Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloi ...
, c. 3500 BC.
In the
Roman era, copper was mined principally on
Cyprus, the origin of the name of the metal, from ''aes cyprium'' (metal of Cyprus), later corrupted to ''cuprum'' (Latin). ''Coper'' (
Old English
Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...
) and ''copper'' were derived from this, the later spelling first used around 1530.
Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as
azurite,
malachite, and
turquoise, and have been used widely and historically as pigments.
Copper used in buildings, usually for roofing, oxidizes to form a green
verdigris (or
patina
Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produced b ...
). Copper is sometimes used in
decorative art
]
The decorative arts are arts or crafts whose object is the design and manufacture of objects that are both beautiful and functional. It includes most of the arts making objects for the interiors of buildings, and interior design, but not usual ...
, both in its elemental metal form and in compounds as pigments. Copper compounds are used as
bacteriostatic agent
A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfect ...
s,
fungicide
Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...
s, and wood preservatives.
Copper is essential to all living organisms as a trace
dietary mineral
In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight (oxygen, hydrogen, carbon ...
because it is a key constituent of the respiratory enzyme complex
cytochrome c oxidase. In
molluscs and
crustacea
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...
ns, copper is a constituent of the blood pigment
hemocyanin, replaced by the iron-complexed
hemoglobin in fish and other
vertebrates. In humans, copper is found mainly in the liver, muscle, and bone. The adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight.
Characteristics
Physical
Copper,
silver, and
gold are in
group 11
Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au), and roentgenium (Rg), although no chemical experiments have yet been carried out to confirm that ...
of the periodic table; these three metals have one s-orbital electron on top of a filled d-
electron shell and are characterized by high
ductility, and electrical and thermal conductivity. The filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through
metallic bonds. Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a
covalent character and are relatively weak. This observation explains the low
hardness and high ductility of
single crystals of copper.
At the macroscopic scale, introduction of extended defects to the
crystal lattice
In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by
: \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n ...
, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is usually supplied in a fine-grained
polycrystalline form, which has greater strength than monocrystalline forms.
The softness of copper partly explains its high electrical conductivity () and high thermal conductivity, second highest (second only to silver) among pure metals at room temperature.
This is because the resistivity to electron transport in metals at room temperature originates primarily from scattering of electrons on thermal vibrations of the lattice, which are relatively weak in a soft metal.
The maximum permissible current density of copper in open air is approximately of cross-sectional area, above which it begins to heat excessively.
Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish
tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light.
As with other metals, if copper is put in contact with another metal,
galvanic corrosion
Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte. A sim ...
will occur.
Chemical
Copper does not react with water, but it does slowly react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the
rust that forms on iron in moist air, protects the underlying metal from further corrosion (
passivation). A green layer of
verdigris (copper carbonate) can often be seen on old copper structures, such as the roofing of many older buildings
and the
Statue of Liberty
The Statue of Liberty (''Liberty Enlightening the World''; French: ''La Liberté éclairant le monde'') is a List of colossal sculpture in situ, colossal neoclassical sculpture on Liberty Island in New York Harbor in New York City, in the U ...
. Copper
tarnishes when exposed to some
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
compounds, with which it reacts to form various
copper sulfides.
Isotopes
There are 29
isotopes of copper. and are stable, with comprising approximately 69% of naturally occurring copper; both have a
spin
Spin or spinning most often refers to:
* Spinning (textiles), the creation of yarn or thread by twisting fibers together, traditionally by hand spinning
* Spin, the rotation of an object around a central axis
* Spin (propaganda), an intentionally b ...
of .
The other isotopes are
radioactive, with the most stable being with a
half-life of 61.83 hours.
Seven
metastable isotopes
In chemistry and physics, metastability denotes an intermediate energetic state within a dynamical system other than the system's state of least energy.
A ball resting in a hollow on a slope is a simple example of metastability. If the ball i ...
have been characterized; is the longest-lived with a half-life of 3.8 minutes. Isotopes with a
mass number above 64 decay by
β−, whereas those with a mass number below 64 decay by
β+.
, which has a half-life of 12.7 hours, decays both ways.
and have significant applications. is used in Cu-PTSM as a
radioactive tracer for
positron emission tomography
Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in Metabolism, metabolic processes, and in other physiological activities including bl ...
.
Occurrence
Copper is produced in massive stars and is present in the Earth's crust in a proportion of about 50 parts per million (ppm).
In nature, copper occurs in a variety of minerals, including
native copper, copper sulfides such as
chalcopyrite,
bornite,
digenite,
covellite, and
chalcocite, copper
sulfosalts
Sulfosalt minerals are sulfide minerals with the general formula , where
*A represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium
*B usually represents semi-metal such as arsenic, antimony, bismuth, a ...
such as
tetrahedite-tennantite, and
enargite, copper carbonates such as
azurite and
malachite, and as copper(I) or copper(II) oxides such as
cuprite and
tenorite, respectively.
The largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the
Keweenaw Peninsula
The Keweenaw Peninsula ( , sometimes locally ) is the northernmost part of Michigan's Upper Peninsula. It projects into Lake Superior and was the site of the first copper boom in the United States, leading to its moniker of "Copper Country." As o ...
in Michigan, US.
Native copper is a
polycrystal, with the largest single crystal ever described measuring . Copper is the 25th most abundant element in
Earth's crust
Earth's crust is Earth's thin outer shell of rock, referring to less than 1% of Earth's radius and volume. It is the top component of the lithosphere, a division of Earth's layers that includes the crust and the upper part of the mantle. The ...
, representing 50
ppm compared with 75 ppm for
zinc, and 14 ppm for
lead.
Typical background concentrations of copper do not exceed in the atmosphere; in soil; in vegetation; 2 μg/L in freshwater and in seawater.
Production
Most copper is mined or
extracted
''Extracted'', also known as ''Extraction'' in the UK, is an independent 2012 American science fiction thriller directed and written by Nir Paniry. Sasha Roiz stars as a scientist whose consciousness becomes trapped in the mind of a convict (Dom ...
as copper sulfides from large
open pit mines in
porphyry copper deposits that contain 0.4 to 1.0% copper. Sites include
Chuquicamata, in Chile,
Bingham Canyon Mine, in Utah, United States, and
El Chino Mine
The Chino Mine ("Chino" is Spanish for the "Chinese"), also known as the Santa Rita mine, also known as Santa Rita del Cobre, is an open-pit porphyry copper mine located in the town of Santa Rita, New Mexico east of Silver City. The mine was s ...
, in New Mexico, United States. According to the
British Geological Survey
The British Geological Survey (BGS) is a partly publicly funded body which aims to advance geoscientific knowledge of the United Kingdom landmass and its continental shelf by means of systematic surveying, monitoring and research.
The BGS h ...
, in 2005, Chile was the top producer of copper with at least one-third of the world share followed by the United States, Indonesia and Peru.
Copper can also be recovered through the
in-situ leach process. Several sites in the state of Arizona are considered prime candidates for this method. The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage. An alternative source of copper for
collection currently being researched are
polymetallic nodules
Polymetallic nodules, also called manganese nodules, are mineral concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core. As nodules can be found in vast quantities, and contain valuable metals, dep ...
, which are located at the depths of the
Pacific Ocean approximately 3000–6500 meters below sea level. These nodules contain other valuable metals such as
cobalt and
nickel.
Reserves and prices
Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined and
smelted has been extracted since 1900.
As with many natural resources, the total amount of copper on Earth is vast, with around 10
14 tons in the top kilometer of Earth's crust, which is about 5 million years' worth at the current rate of extraction. However, only a tiny fraction of these reserves is economically viable with present-day prices and technologies. Estimates of copper reserves available for mining vary from 25 to 60 years, depending on core assumptions such as the growth rate. Recycling is a major source of copper in the modern world.
Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of
peak copper, analogous to
peak oil.
The price of copper has historically been unstable, and its price increased from the 60-year low of US$0.60/lb (US$1.32/kg) in June 1999 to $3.75 per pound ($8.27/kg) in May 2006. It dropped to $2.40/lb ($5.29/kg) in February 2007, then rebounded to $3.50/lb ($7.71/kg) in April 2007. In February 2009, weakening global demand and a steep fall in commodity prices since the previous year's highs left copper prices at $1.51/lb ($3.32/kg). Between September 2010 and February 2011, the price of copper rose from £5,000 a metric ton to £6,250 a metric ton.
Methods
The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS
2), bornite (Cu
5FeS
4) and, to a lesser extent, covellite (CuS) and chalcocite (Cu
2S).
Conversely, the average concentration of copper in polymetallic nodules is estimated at 1.3%. The methods of extracting copper as well as other metals found in these nodules include sulphuric leaching,
smelting and an application of the Cuprion process. For minerals found in land ores, they are concentrated from
crushed ores to the level of 10–15% copper by
froth flotation or
bioleaching. Heating this material with
silica in
flash smelting removes much of the iron as
slag
Slag is a by-product of smelting (pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-prod ...
. The process exploits the greater ease of converting iron sulfides into oxides, which in turn react with the silica to form the
silicate
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is al ...
slag that floats on top of the heated mass. The resulting ''copper matte,'' consisting of Cu
2S, is
roasted to convert the sulfides into oxides:
:2 Cu
2S + 3 O
2 → 2 Cu
2O + 2 SO
2
The cuprous oxide reacts with cuprous sulfide to converted to ''blister'' copper upon heating:
:2 Cu
2O + Cu
2S → 6 Cu + 2 SO
2
The Sudbury
matte process converted only half the sulfide to oxide and then used this oxide to remove the rest of the sulfur as oxide. It was then electrolytically refined and the anode mud exploited for the
platinum and gold it contained. This step exploits the relatively easy reduction of copper oxides to copper metal.
Natural gas is blown across the blister to remove most of the remaining oxygen and
electrorefining is performed on the resulting material to produce pure copper:
:Cu
2+ + 2 e
− → Cu
Recycling
Like
aluminium
Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...
, copper is recyclable without any loss of quality, both from raw state and from manufactured products. In volume, copper is the third most recycled metal after iron and aluminium. An estimated 80% of all copper ever mined is still in use today. According to the
International Resource Panel's
Metal Stocks in Society report
The report Metal Stocks in Society: Scientific Synthesis was the first of six scientific assessments on global metals to be published by the International Resource Panel (IRP) of the United Nations Environment Programme. The IRP provides independe ...
, the global per capita stock of copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita).
The process of recycling copper is roughly the same as is used to extract copper but requires fewer steps. High-purity scrap copper is melted in a
furnace and then
reduced and cast into
billets and
ingots; lower-purity scrap is refined by
electroplating
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be ...
in a bath of
sulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...
.
Alloys
Numerous copper
alloys have been formulated, many with important uses.
Brass is an alloy of copper and
zinc.
Bronze
Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloi ...
usually refers to copper-
tin alloys, but can refer to any alloy of copper such as
aluminium bronze. Copper is one of the most important constituents of silver and
karat gold solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys.
Some lead-free
solders consist of tin alloyed with a small proportion of copper and other metals.
The alloy of copper and
nickel, called
cupronickel, is used in low-denomination coins, often for the outer cladding. The US five-cent coin (currently called a ''nickel'') consists of 75% copper and 25% nickel in homogeneous composition. Prior to the introduction of cupronickel, which was widely adopted by countries in the latter half of the 20th century, alloys of copper and
silver were also used, with the United States using an alloy of 90% silver and 10% copper until 1965, when circulating silver was removed from all coins with the exception of the Half dollar - these were debased to an alloy of 40% silver and 60% copper between 1965 and 1970. The alloy of 90% copper and 10% nickel, remarkable for its resistance to corrosion, is used for various objects exposed to seawater, though it is vulnerable to the sulfides sometimes found in polluted harbors and estuaries. Alloys of copper with aluminium (about 7%) have a golden color and are used in decorations.
''
Shakudō'' is a Japanese decorative alloy of copper containing a low percentage of gold, typically 4–10%, that can be
patina
Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produced b ...
ted to a dark blue or black color.
Compounds
Copper forms a rich variety of compounds, usually with
oxidation states +1 and +2, which are often called ''cuprous'' and ''cupric'', respectively.
Copper compounds, whether organic
complexes or
organometallic
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...
s, promote or catalyse numerous chemical and biological processes.
Binary compounds
As with other elements, the simplest compounds of copper are binary compounds, i.e. those containing only two elements, the principal examples being oxides, sulfides, and
halide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...
s. Both
cuprous and
cupric oxides are known. Among the numerous
copper sulfides, important examples include
copper(I) sulfide and
copper(II) sulfide.
Cuprous halides with
fluorine
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...
,
chlorine,
bromine, and
iodine
Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...
are known, as are cupric halides with
fluorine
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...
,
chlorine, and
bromine. Attempts to prepare copper(II) iodide yield only copper(I) iodide and iodine.
:2 Cu
2+ + 4 I
− → 2 CuI + I
2
Coordination chemistry
Copper forms
coordination complexes with
ligands. In aqueous solution, copper(II) exists as . This complex exhibits the fastest water exchange rate (speed of water ligands attaching and detaching) for any transition
metal aquo complex. Adding aqueous
sodium hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions .
Sodium hydroxide is a highly caustic base and alkali ...
causes the precipitation of light blue solid
copper(II) hydroxide. A simplified equation is:
:Cu
2+ + 2 OH
− → Cu(OH)
2
Aqueous ammonia results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, forming
tetraamminecopper(II):
: + 4 NH
3 → + 2 H
2O + 2 OH
−
Many other
oxyanions form complexes; these include
copper(II) acetate,
copper(II) nitrate, and
copper(II) carbonate.
Copper(II) sulfate forms a blue crystalline penta
hydrate
In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...
, the most familiar copper compound in the laboratory. It is used in a
fungicide
Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...
called the
Bordeaux mixture
Bordeaux mixture (also called ''Bordo Mix'') is a mixture of copper(II) sulphate (CuSO4) and quicklime ( Ca O) used as a fungicide. It is used in vineyards, fruit-farms and gardens to prevent infestations of downy mildew, powdery mildew and other ...
.
Polyols, compounds containing more than one alcohol
functional group, generally interact with cupric salts. For example, copper salts are used to test for
reducing sugars
A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a reactio ...
. Specifically, using
Benedict's reagent and
Fehling's solution the presence of the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide. Schweizer's reagent and related complexes with
ethylenediamine
Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a basic amine. It is a widely used building block in chemical synthesis, with approximately ...
and other
amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent su ...
s dissolve
cellulose.
Amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s form very stable
chelate complexes with copper(II). including in the form of
metal-organic biohybrids (MOBs). Many wet-chemical tests for copper ions exist, one involving
potassium ferrocyanide, which gives a brown precipitate with copper(II) salts.
Organocopper chemistry
Compounds that contain a carbon-copper bond are known as organocopper compounds. They are very reactive towards oxygen to form copper(I) oxide and have
many uses in chemistry. They are synthesized by treating copper(I) compounds with
Grignard reagents,
terminal alkyne
\ce
\ce
Acetylene
\ce
\ce
\ce
Propyne
\ce
\ce
\ce
\ce
1-Butyne
In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and no ...
s or
organolithium reagents; in particular, the last reaction described produces a
Gilman reagent
A Gilman reagent is a lithium and copper ( diorganocopper) reagent compound, R2CuLi, where R is an alkyl or aryl. These reagents are useful because, unlike related Grignard reagents and organolithium reagents, they react with organic halides ...
. These can undergo
substitution
Substitution may refer to:
Arts and media
*Chord substitution, in music, swapping one chord for a related one within a chord progression
* Substitution (poetry), a variation in poetic scansion
* "Substitution" (song), a 2009 song by Silversun Pi ...
with
alkyl halides to form
coupling products; as such, they are important in the field of
organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
.
Copper(I) acetylide is highly shock-sensitive but is an intermediate in reactions such as the
Cadiot-Chodkiewicz coupling and the
Sonogashira coupling.
Conjugate addition to
enones and
carbocupration of alkynes can also be achieved with organocopper compounds. Copper(I) forms a variety of weak complexes with
alkenes and
carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
, especially in the presence of amine ligands.
Copper(III) and copper(IV)
Copper(III) is most often found in oxides. A simple example is potassium
cuprate, KCuO
2, a blue-black solid. The most extensively studied copper(III) compounds are the
cuprate superconductors.
Yttrium barium copper oxide (YBa
2Cu
3O
7) consists of both Cu(II) and Cu(III) centres. Like oxide,
fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an inorganic, monatomic anion of fluorine, with the chemical formula (also written ), whose salts are typically white or colorless. Fluoride salts typ ...
is a highly
basic
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
anion and is known to stabilize metal ions in high oxidation states. Both copper(III) and even copper(IV) fluorides are known,
K3CuF6 and
Cs2CuF6, respectively.
Some copper proteins form
oxo complex
A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligan ...
es, which also feature copper(III). With
tetrapeptides, purple-colored copper(III) complexes are stabilized by the deprotonated
amide ligands.
Complexes of copper(III) are also found as intermediates in reactions of organocopper compounds. For example, in the
Kharasch–Sosnovsky reaction The Kharasch–Sosnovsky reaction is the radical oxidation of an allylic alkene to a allylic alcohol using a copper catalyst and a peroxy ester (e.g. tert-Butyl peroxybenzoate) or a peroxide. Chiral ligands can be used to render the reaction asym ...
.
History
A timeline of copper illustrates how this metal has advanced human civilization for the past 11,000 years.
Prehistoric
Copper Age
Copper occurs naturally as
native metallic copper and was known to some of the oldest civilizations on record. The history of copper use dates to 9000 BC in the Middle East;
a copper pendant was found in northern Iraq that dates to 8700 BC. Evidence suggests that gold and
meteoric iron (but not smelted iron) were the only metals used by humans before copper.
The history of copper metallurgy is thought to follow this sequence: First,
cold working of native copper, then
annealing,
smelting, and, finally,
lost-wax casting. In southeastern
Anatolia, all four of these techniques appear more or less simultaneously at the beginning of the
Neolithic c. 7500 BC.
Copper smelting was independently invented in different places. It was probably discovered in China before 2800 BC, in Central America around 600 AD, and in West Africa about the 9th or 10th century AD.
Investment casting was invented in 4500–4000 BC in Southeast Asia
and
carbon dating
Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
The method was dev ...
has established mining at
Alderley Edge in
Cheshire
Cheshire ( ) is a ceremonial and historic county in North West England, bordered by Wales to the west, Merseyside and Greater Manchester to the north, Derbyshire to the east, and Staffordshire and Shropshire to the south. Cheshire's county t ...
, UK, at 2280 to 1890 BC.
Ötzi the Iceman, a male dated from 3300 to 3200 BC, was found with an axe with a copper head 99.7% pure; high levels of
arsenic in his hair suggest an involvement in copper smelting.
Experience with copper has assisted the development of other metals; in particular, copper smelting led to the discovery of
iron smelting.
Production in the
Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC.
[Pleger, Thomas C. "A Brief Introduction to the Old Copper Complex of the Western Great Lakes: 4000–1000 BC", ]
Proceedings of the Twenty-Seventh Annual Meeting of the Forest History Association of Wisconsin
', Oconto, Wisconsin, 5 October 2002, pp. 10–18. Natural bronze, a type of copper made from ores rich in silicon, arsenic, and (rarely) tin, came into general use in the Balkans around 5500 BC.
Bronze Age
Alloying copper with tin to make bronze was first practiced about 4000 years after the discovery of copper smelting, and about 2000 years after "natural bronze" had come into general use. Bronze artifacts from the
Vinča culture date to 4500 BC.
Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is one of the cradles of c ...
ian and
Egyptian artifacts of copper and bronze alloys date to 3000 BC.
The
Bronze Age
The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second pri ...
began in Southeastern Europe around 3700–3300 BC, in Northwestern Europe about 2500 BC. It ended with the beginning of the Iron Age, 2000–1000 BC in the Near East, and 600 BC in Northern Europe. The transition between the
Neolithic period and the Bronze Age was formerly termed the
Chalcolithic
The Copper Age, also called the Chalcolithic (; from grc-gre, χαλκός ''khalkós'', " copper" and ''líthos'', " stone") or (A)eneolithic (from Latin ''aeneus'' "of copper"), is an archaeological period characterized by regul ...
period (copper-stone), when copper tools were used with stone tools. The term has gradually fallen out of favor because in some parts of the world, the Chalcolithic and Neolithic are coterminous at both ends. Brass, an alloy of copper and zinc, is of much more recent origin. It was known to the Greeks, but became a significant supplement to bronze during the Roman Empire.
Ancient and post-classical
In Greece, copper was known by the name (χαλκός). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as ''aes Cyprium'', ''aes'' being the generic Latin term for copper alloys and ''Cyprium'' from
Cyprus, where much copper was mined. The phrase was simplified to ''cuprum'', hence the English ''copper''.
Aphrodite
Aphrodite ( ; grc-gre, Ἀφροδίτη, Aphrodítē; , , ) is an ancient Greek religion, ancient Greek goddess associated with love, lust, beauty, pleasure, passion (emotion), passion, and procreation. She was syncretized with the Roman god ...
(
Venus in Rome) represented copper in mythology and alchemy because of its lustrous beauty and its ancient use in producing mirrors; Cyprus, the source of copper, was sacred to the goddess. The seven heavenly bodies known to the ancients were associated with the seven metals known in antiquity, and Venus was assigned to copper, both because of the connection to the goddess and because Venus was the brightest heavenly body after the Sun and Moon and so corresponded to the most lustrous and desirable metal after gold and silver.
Copper was first mined in ancient Britain as early as 2100 BC. Mining at the largest of these mines, the
Great Orme, continued into the late Bronze Age. Mining seems to have been largely restricted to
supergene
A supergene is a chromosomal region encompassing multiple neighboring genes that are inherited together because of close genetic linkage, i.e. much less recombination than would normally be expected. This mode of inheritance can be due to genomic ...
ores, which were easier to smelt. The rich copper deposits of
Cornwall seem to have been largely untouched, in spite of extensive
tin mining in the region, for reasons likely social and political rather than technological.
In North America, copper mining began with marginal workings by Native Americans. Native copper is known to have been extracted from sites on
Isle Royale with primitive stone tools between 800 and 1600. Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD. Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century.
The cultural role of copper has been important, particularly in currency. Romans in the 6th through 3rd centuries BC used copper lumps as money. At first, the copper itself was valued, but gradually the shape and look of the copper became more important.
Julius Caesar
Gaius Julius Caesar (; ; 12 July 100 BC – 15 March 44 BC), was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in a civil war, and ...
had his own coins made from brass, while
Octavianus Augustus Caesar's coins were made from Cu-Pb-Sn alloys. With an estimated annual output of around 15,000 t,
Roman copper mining and smelting activities reached a scale unsurpassed until the time of the
Industrial Revolution; the
provinces most intensely mined were those of
Hispania,
Cyprus and in Central Europe.
The gates of the
Temple of Jerusalem used
Corinthian bronze treated with
depletion gilding. The process was most prevalent in
Alexandria, where alchemy is thought to have begun. In ancient
India, copper was used in the
holistic medical science
Ayurveda for
surgical instruments and other medical equipment.
Ancient Egyptians (
~2400 BC) used copper for sterilizing wounds and drinking water, and later to treat headaches, burns, and itching.
Modern
The
Great Copper Mountain was a mine in Falun, Sweden, that operated from the 10th century to 1992. It satisfied two-thirds of Europe's copper consumption in the 17th century and helped fund many of Sweden's wars during that time. It was referred to as the nation's treasury; Sweden had a
copper backed currency.
Copper is used in roofing,
currency, and for photographic technology known as the
daguerreotype
Daguerreotype (; french: daguerréotype) was the first publicly available photographic process; it was widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process.
Invented by Louis Daguerre an ...
. Copper was used in
Renaissance sculpture, and was used to construct the
Statue of Liberty
The Statue of Liberty (''Liberty Enlightening the World''; French: ''La Liberté éclairant le monde'') is a List of colossal sculpture in situ, colossal neoclassical sculpture on Liberty Island in New York Harbor in New York City, in the U ...
; copper continues to be used in construction of various types.
Copper plating and
copper sheathing were widely used to protect the under-water hulls of ships, a technique pioneered by the British Admiralty in the 18th century. The
Norddeutsche Affinerie in Hamburg was the first modern
electroplating
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be ...
plant, starting its production in 1876. The German scientist
Gottfried Osann invented
powder metallurgy in 1830 while determining the metal's atomic mass; around then it was discovered that the amount and type of alloying element (e.g., tin) to copper would affect bell tones.
During the rise in demand for copper for the Age of Electricity, from the 1880s until the Great Depression of the 1930s, the United States produced one third to half the world's newly mined copper. Major districts included the Keweenaw district of northern Michigan, primarily native copper deposits, which was eclipsed by the vast sulphide deposits of
Butte, Montana
Butte ( ) is a consolidated city-county and the county seat of Silver Bow County, Montana, United States. In 1977, the city and county governments consolidated to form the sole entity of Butte-Silver Bow. The city covers , and, according to the ...
in the late 1880s, which itself was eclipsed by porphyry deposits of the Souhwest United States, especially at
Bingham Canyon, Utah and
Morenci, Arizona. Introduction of open pit steam shovel mining and innovations in smelting, refining, flotation concentration and other processing steps led to mass production. Early in the twentieth century,
Arizona ranked first, followed by
Montana, then
Utah and
Michigan.
Flash smelting was developed by
Outokumpu in Finland and first applied at
Harjavalta in 1949; the energy-efficient process accounts for 50% of the world's primary copper production.
The
Intergovernmental Council of Copper Exporting Countries, formed in 1967 by Chile, Peru, Zaire and Zambia, operated in the copper market as
OPEC
The Organization of the Petroleum Exporting Countries (OPEC, ) is a cartel of countries. Founded on 14 September 1960 in Baghdad by the first five members (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela), it has, since 1965, been headquart ...
does in oil, though it never achieved the same influence, particularly because the second-largest producer, the United States, was never a member; it was dissolved in 1988.
Applications
The major applications of copper are electrical wire (60%), roofing and plumbing (20%), and industrial machinery (15%). Copper is used mostly as a pure metal, but when greater hardness is required, it is put into such alloys as
brass and
bronze
Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloi ...
(5% of total use).
For more than two centuries, copper paint has been used on boat hulls to control the growth of plants and shellfish. A small part of the copper supply is used for nutritional supplements and fungicides in agriculture.
Machining
Machining is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, which utilizes ...
of copper is possible, although alloys are preferred for good
machinability in creating intricate parts.
Wire and cable
Despite competition from other materials, copper remains the preferred
electrical conductor in nearly all categories of electrical wiring except overhead
electric power transmission
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a ''transmission network''. This is ...
where
aluminium
Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately o ...
is often preferred. Copper wire is used in
power generation
Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery ( transmission, distribution, etc.) to end users or its stor ...
,
power transmission,
power distribution,
telecommunications,
electronics circuitry, and countless types of
electrical equipment
Electric(al) devices are devices that functionally rely on electric energy ( AC or DC) to drive their core parts (electric motors, transformers, lighting, rechargeable batteries, control electronics). They can be contrasted with traditional mech ...
.
Electrical wiring
Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure.
Wiring is subject to safety standards for design and installation. Allowable ...
is the most important market for the copper industry. This includes structural power wiring, power distribution cable, appliance wire, communications cable, automotive wire and cable, and magnet wire. Roughly half of all copper mined is used for electrical wire and cable conductors. Many electrical devices rely on copper wiring because of its multitude of inherent beneficial properties, such as its high
electrical conductivity
Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...
,
tensile strength,
ductility,
creep (deformation) resistance,
corrosion resistance, low
thermal expansion, high
thermal conductivity, ease of
soldering,
malleability
Ductility is a List of materials properties, mechanical property commonly described as a material's amenability to Drawing (manufacturing), drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a materia ...
, and ease of installation.
For a short period from the late 1960s to the late 1970s, copper wiring was replaced by
aluminium wiring in many housing construction projects in America. The new wiring was implicated in a number of house fires and the industry returned to copper.
Electronics and related devices
Integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
s and
printed circuit board
A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in Electrical engineering, electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a L ...
s increasingly feature copper in place of aluminium because of its superior electrical conductivity;
heat sinks and
heat exchangers use copper because of its superior heat dissipation properties.
Electromagnets,
vacuum tubes,
cathode ray tube
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms ( oscilloscope), pictu ...
s, and
magnetrons in microwave ovens use copper, as do
waveguides for microwave radiation.
Electric motors
Copper's superior
conductivity enhances the efficiency of electrical
motors. This is important because motors and motor-driven systems account for 43%–46% of all global electricity consumption and 69% of all electricity used by industry. Increasing the mass and cross section of copper in a
coil increases the efficiency of the motor.
Copper motor rotors, a new technology designed for motor applications where energy savings are prime design objectives, are enabling general-purpose
induction motor
An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction mot ...
s to meet and exceed
National Electrical Manufacturers Association (NEMA)
premium efficiency standards.
Renewable energy production
Architecture
Copper has been used since ancient times as a durable,
corrosion resistant, and weatherproof architectural material.
Roofs,
flashings,
rain gutters,
downspouts,
dome
A dome () is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a m ...
s,
spires, vaults, and
door
A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a ''doorway'' or ''portal''. A door's essential and primary purpose is to provide security b ...
s have been made from copper for hundreds or thousands of years. Copper's architectural use has been expanded in modern times to include interior and exterior
wall cladding, building
expansion joints,
radio frequency shielding, and
antimicrobial and decorative indoor products such as attractive handrails, bathroom fixtures, and counter tops. Some of copper's other important benefits as an architectural material include low
thermal movement, light weight,
lightning protection, and recyclability
The metal's distinctive natural green
patina
Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze and similar metals and metal alloys (tarnish produced by oxidation or other chemical processes) or certain stones and wooden furniture (sheen produced b ...
has long been coveted by architects and designers. The final patina is a particularly durable layer that is highly resistant to atmospheric corrosion, thereby protecting the underlying metal against further weathering. It can be a mixture of carbonate and sulfate compounds in various amounts, depending upon environmental conditions such as sulfur-containing acid rain. Architectural copper and its alloys can also be
'finished' to take on a particular look, feel, or color. Finishes include mechanical surface treatments, chemical coloring, and coatings.
Copper has excellent
brazing and
soldering properties and can be
welded; the best results are obtained with
gas metal arc welding.
Antibiofouling
Copper is
biostatic, meaning bacteria and many other forms of life will not grow on it. For this reason it has long been used to line parts of ships to protect against
barnacle
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...
s and
mussel
Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...
s. It was originally used pure, but has since been superseded by
Muntz metal and copper-based paint. Similarly, as discussed in
copper alloys in aquaculture, copper alloys have become important netting materials in the
aquaculture
Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...
industry because they are
antimicrobial and prevent
biofouling, even in extreme conditions
[Edding, Mario E., Flores, Hector, and Miranda, Claudio, (1995), Experimental Usage of Copper-Nickel Alloy Mesh in Mariculture. Part 1: Feasibility of usage in a temperate zone; Part 2: Demonstration of usage in a cold zone; Final report to the International Copper Association Ltd.] and have strong structural and
corrosion-resistant properties in marine environments.
Antimicrobial
Copper-alloy touch surfaces have natural properties that destroy a wide range of
microorganisms
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
(e.g., ''
E. coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
'' O157:H7,
methicillin-resistant ''
Staphylococcus aureus
''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...
'' (
MRSA), ''
Staphylococcus
''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. ''Staphylococcus'' species are facultative ...
'', ''
Clostridium difficile
''Clostridioides difficile'' (syn. ''Clostridium difficile'') is a bacterium that is well known for causing serious diarrheal infections, and may also cause colon cancer. Also known as ''C. difficile'', or ''C. diff'' (), is Gram-positive spec ...
'',
influenza A virus
''Influenza A virus'' (''IAV'') causes influenza in birds and some mammals, and is the only species of the genus ''Alphainfluenzavirus'' of the virus family ''Orthomyxoviridae''. Strain (biology)#Microbiology or virology, Strains of all subtypes ...
,
adenovirus
Adenoviruses (members of the family ''Adenoviridae'') are medium-sized (90–100 nm), nonenveloped (without an outer lipid bilayer) viruses with an icosahedral nucleocapsid containing a double-stranded DNA genome. Their name derives from the ...
,
SARS-Cov-2, and
fungi).
[Copper Touch Surfaces](_blank)
. Copper Touch Surfaces. Retrieved on 8 November 2011. Indians have been using copper vessels since ancient times for storing water, even before modern science realized its antimicrobial properties.
Some copper alloys were proven to kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly.
The
United States Environmental Protection Agency (EPA) has approved the registrations of these copper alloys as "
antimicrobial materials with public health benefits";
that approval allows manufacturers to make legal claims to the public health benefits of products made of registered alloys. In addition, the EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails,
handrails, over-bed tables,
sinks
A sink is a bowl-shaped plumbing fixture for washing hands, dishwashing, and other purposes. Sinks have a tap (faucet) that supply hot and cold water and may include a spray feature to be used for faster rinsing. They also include a drain to ...
,
faucets,
door knobs
A door handle or doorknob is a handle used to open or close a door. Door handles can be found on all types of doors including exterior doors of residential and commercial buildings, internal doors, cupboard doors and vehicle doors. There are many ...
,
toilet hardware,
computer keyboards,
health club
A health club (also known as a fitness club, fitness center, health spa, and commonly referred to as a gym) is a place that houses exercise equipment for the purpose of physical exercise.
In recent years, the number of fitness and health se ...
equipment, and
shopping cart handles (for a comprehensive list, see:
Antimicrobial copper-alloy touch surfaces#Approved products). Copper doorknobs are used by hospitals to reduce the transfer of disease, and
Legionnaires' disease
Legionnaires' disease is a form of atypical pneumonia caused by any species of ''Legionella'' bacteria, quite often '' Legionella pneumophila''. Signs and symptoms include cough, shortness of breath, high fever, muscle pains, and headaches. Naus ...
is suppressed by copper tubing in plumbing systems. Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil, as well as being called for in the US, and in the subway transit system in Santiago, Chile, where copper-zinc alloy handrails were installed in some 30 stations between 2011 and 2014.
Textile fibers can be blended with copper to create antimicrobial protective fabrics.
Speculative investing
Copper may be used as a speculative investment due to the predicted increase in use from worldwide infrastructure growth, and the important role it has in producing
wind turbines,
solar panel
A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...
s, and other renewable energy sources. Another reason predicted demand increases is the fact that
electric car
An electric car, battery electric car, or all-electric car is an automobile that is propelled by one or more electric motors, using only energy stored in batteries. Compared to internal combustion engine (ICE) vehicles, electric cars are quie ...
s contain an average of 3.6 times as much copper as conventional cars, although the effect of
electric cars on copper demand is debated. Some people invest in copper through copper mining stocks,
ETFs, and
futures
Futures may mean:
Finance
*Futures contract, a tradable financial derivatives contract
*Futures exchange, a financial market where futures contracts are traded
* ''Futures'' (magazine), an American finance magazine
Music
* ''Futures'' (album), a ...
. Others store physical copper in the form of copper bars or rounds although these tend to carry a higher premium in comparison to precious metals. Those who want to avoid the premiums of copper
bullion
Bullion is non-ferrous metal that has been refined to a high standard of elemental purity. The term is ordinarily applied to bulk metal used in the production of coins and especially to precious metals such as gold and silver. It comes from t ...
alternatively store old
copper wire,
copper tubing or American
pennies made before 1982.
Folk medicine
Copper is commonly used in jewelry, and according to some folklore, copper bracelets relieve
arthritis
Arthritis is a term often used to mean any disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, swelling, and decreased range of motion of the affected joints. In som ...
symptoms. In one trial for osteoarthritis and one trial for rheumatoid arthritis, no differences is found between copper bracelet and control (non-copper) bracelet.
No evidence shows that copper can be absorbed through the skin. If it were, it might lead to
copper poisoning
Copper toxicity (or Copperiedus) is a type of metal poisoning caused by an excess of copper in the body. Copperiedus could occur from consuming excess copper salts, but most commonly it is the result of the genetic condition Wilson's disease an ...
.
Compression clothing
Recently, some
compression clothing with inter-woven copper has been marketed with health claims similar to the folk medicine claims. Because compression clothing is a valid treatment for some ailments, the clothing may have that benefit, but the added copper may have no benefit beyond a
placebo effect.
Degradation
''
Chromobacterium violaceum'' and ''
Pseudomonas fluorescens
''Pseudomonas fluorescens'' is a common Gram-negative, rod-shaped bacterium. It belongs to the ''Pseudomonas'' genus; 16S rRNA analysis as well as phylogenomic analysis has placed ''P. fluorescens'' in the ''P. fluorescens'' group within the genu ...
'' can both mobilize solid copper as a cyanide compound.
The ericoid mycorrhizal fungi associated with ''Calluna'', ''Erica'' and ''Vaccinium'' can grow in metalliferous soils containing copper.
The ectomycorrhizal fungus ''Suillus luteus'' protects young pine trees from copper toxicity. A sample of the fungus ''
Aspergillus niger'' was found growing from gold mining solution and was found to contain cyano complexes of such metals as gold, silver, copper, iron, and zinc. The fungus also plays a role in the solubilization of heavy metal sulfides.
Biological role
Biochemistry
Copper proteins have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II). Copper is essential in the aerobic
respiration of all
eukaryotes
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...
. In
mitochondria
A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
, it is found in
cytochrome c oxidase, which is the last protein in
oxidative phosphorylation
Oxidative phosphorylation (UK , US ) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine tri ...
. Cytochrome c oxidase is the protein that binds the O
2 between a copper and an iron; the protein transfers 8 electrons to the O
2 molecule to reduce it to two molecules of water. Copper is also found in many
superoxide dismutase
Superoxide dismutase (SOD, ) is an enzyme that alternately catalyzes the dismutation (or partitioning) of the superoxide () radical into ordinary molecular oxygen (O2) and hydrogen peroxide (). Superoxide is produced as a by-product of oxygen me ...
s, proteins that catalyze the decomposition of
superoxides by converting it (by
disproportionation) to oxygen and
hydrogen peroxide:
* Cu
2+-SOD + O
2− → Cu
+-SOD + O
2 (reduction of copper; oxidation of superoxide)
* Cu
+-SOD + O
2− + 2H
+ → Cu
2+-SOD + H
2O
2 (oxidation of copper; reduction of superoxide)
The protein
hemocyanin is the oxygen carrier in most
mollusks and some
arthropods such as the
horseshoe crab (''Limulus polyphemus'').
Because hemocyanin is blue, these organisms have blue blood rather than the red blood of iron-based
hemoglobin. Structurally related to hemocyanin are the
laccases and
tyrosinases. Instead of reversibly binding oxygen, these proteins hydroxylate substrates, illustrated by their role in the formation of
lacquer
Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity.
Asian lacquerware, which may be ca ...
s.
[S.J. Lippard, J.M. Berg "Principles of bioinorganic chemistry" University Science Books: Mill Valley, CA; 1994. .] The biological role for copper commenced with the appearance of oxygen in earth's atmosphere. Several copper proteins, such as the "blue copper proteins", do not interact directly with substrates; hence they are not enzymes. These proteins relay electrons by the process called
electron transfer.
A unique tetranuclear copper center has been found in
nitrous-oxide reductase
In enzymology, a nitrous oxide reductase also known as nitrogen:acceptor oxidoreductase (N2O-forming) is an enzyme that catalyzes the final step in bacterial denitrification, the reduction of nitrous oxide to dinitrogen.
: N2O + 2 reduced cytocho ...
.
Chemical compounds which were developed for treatment of Wilson's disease have been investigated for use in cancer therapy.
Nutrition
Copper is an essential
trace element in plants and animals, but not all microorganisms. The human body contains copper at a level of about 1.4 to 2.1 mg per kg of body mass.
Absorption
Copper is absorbed in the gut, then transported to the liver bound to
albumin. After processing in the liver, copper is distributed to other tissues in a second phase, which involves the protein
ceruloplasmin, carrying the majority of copper in blood. Ceruloplasmin also carries the copper that is excreted in milk, and is particularly well-absorbed as a copper source. Copper in the body normally undergoes
enterohepatic circulation (about 5 mg a day, vs. about 1 mg per day absorbed in the diet and excreted from the body), and the body is able to excrete some excess copper, if needed, via
bile
Bile (from Latin ''bilis''), or gall, is a dark-green-to-yellowish-brown fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine. In humans, bile is produced continuously by the liver (liver bile ...
, which carries some copper out of the liver that is not then reabsorbed by the intestine.
Dietary recommendations
The
U.S. Institute of Medicine
The National Academy of Medicine (NAM), formerly called the Institute of Medicine (IoM) until 2015, is an American nonprofit, non-governmental organization. The National Academy of Medicine is a part of the National Academies of Sciences, Eng ...
(IOM) updated the estimated average requirements (EARs) and recommended dietary allowances (RDAs) for copper in 2001. If there is not sufficient information to establish EARs and RDAs, an estimate designated
Adequate Intake (AI) is used instead. The AIs for copper are: 200 μg of copper for 0–6-month-old males and females, and 220 μg of copper for 7–12-month-old males and females. For both sexes, the RDAs for copper are: 340 μg of copper for 1–3 years old, 440 μg of copper for 4–8 years old, 700 μg of copper for 9–13 years old, 890 μg of copper for 14–18 years old and 900 μg of copper for ages 19 years and older. For pregnancy, 1,000 μg. For lactation, 1,300 μg. As for safety, the IOM also sets
tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of copper the UL is set at 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as
Dietary Reference Intakes.
The
European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women and men ages 18 and older the AIs are set at 1.3 and 1.6 mg/day, respectively. AIs for pregnancy and lactation is 1.5 mg/day. For children ages 1–17 years the AIs increase with age from 0.7 to 1.3 mg/day. These AIs are higher than the U.S. RDAs. The European Food Safety Authority reviewed the same safety question and set its UL at 5 mg/day, which is half the U.S. value.
For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For copper labeling purposes 100% of the Daily Value was 2.0 mg, but it was revised to 0.9 mg to bring it into agreement with the RDA.
A table of the old and new adult daily values is provided at
Reference Daily Intake.
Deficiency
Because of its role in facilitating iron uptake,
copper deficiency can produce
anemia-like symptoms,
neutropenia
Neutropenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteria ...
, bone abnormalities, hypopigmentation, impaired growth, increased incidence of infections, osteoporosis, hyperthyroidism, and abnormalities in glucose and cholesterol metabolism. Conversely,
Wilson's disease causes an accumulation of copper in body tissues.
Severe deficiency can be found by testing for low plasma or serum copper levels, low ceruloplasmin, and low red blood cell superoxide dismutase levels; these are not sensitive to marginal copper status. The "cytochrome c oxidase activity of leucocytes and platelets" has been stated as another factor in deficiency, but the results have not been confirmed by replication.
Toxicity
Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, possibly due to redox cycling and the generation of
reactive oxygen species that damage
DNA. Corresponding amounts of copper salts (30 mg/kg) are toxic in animals. A minimum dietary value for healthy growth in rabbits has been reported to be at least 3
ppm in the diet. However, higher concentrations of copper (100 ppm, 200 ppm, or 500 ppm) in the diet of rabbits may favorably influence
feed conversion efficiency, growth rates, and carcass dressing percentages.
Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. Autosomal recessive mutations in copper transport proteins can disable these systems, leading to
Wilson's disease with copper accumulation and
cirrhosis of the liver in persons who have inherited two defective genes.
Elevated copper levels have also been linked to worsening symptoms of
Alzheimer's disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...
.
Human exposure
In the US, the
Occupational Safety and Health Administration (OSHA) has designated a
permissible exposure limit (PEL) for copper dust and fumes in the workplace as a time-weighted average (TWA) of 1 mg/m
3. The
National Institute for Occupational Safety and Health (NIOSH) has set a
recommended exposure limit (REL) of 1 mg/m
3, time-weighted average. The
IDLH (immediately dangerous to life and health) value is 100 mg/m
3.
Copper is a constituent of
tobacco smoke.
The
tobacco plant
''Nicotiana'' () is a genus of herbaceous plants and shrubs in the family Solanaceae, that is indigenous to the Americas, Australia, Southwestern Africa and the South Pacific. Various ''Nicotiana'' species, commonly referred to as tobacco plants ...
readily absorbs and accumulates
heavy metals
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Heavy metals are generally defined as ...
, such as copper from the surrounding soil into its leaves. These are readily absorbed into the user's body following smoke inhalation. The health implications are not clear.
See also
*
Copper in renewable energy
*
Copper nanoparticle
*
Erosion corrosion of copper water tubes
**
Cold water pitting of copper tube
*
List of countries by copper production
*
Metal theft
**
Operation Tremor
Operation Tremor was a joint operation between British Transport Police, Lancashire Constabulary and Network Rail to combat thieves who had been stealing copper boilers, cables and piping from train tracks, which could disable signalling equipment ...
*
Anaconda Copper
The Anaconda Copper Mining Company, known as the Amalgamated Copper Company between 1899 to 1915, was an American mining company headquartered in Butte, Montana. It was one of the largest trusts of the early 20th century and one of the largest min ...
*
Antofagasta PLC
*
Codelco
*
El Boleo mine
*
Grasberg mine
References
Notes
Further reading
*
*
* Current Medicinal Chemistry, Volume 12, Number 10, May 2005, pp. 1161–1208(48) Metals, Toxicity and Oxidative Stress
*
Material: Copper (Cu), bulk MEMS and Nanotechnology Clearinghouse.
*
External links
at ''
The Periodic Table of Videos'' (University of Nottingham)
Copper and compounds fact sheetfrom the
National Pollutant Inventory of Australia
Copper.org– official website of the Copper Development Association with an extensive site of properties and uses of copper
Price history of copper, according to the IMF
{{good article
Chemical elements
Transition metals
Dietary minerals
Electrical conductors
Cubic minerals
Crystals in space group 225
Native element minerals
Symbols of Arizona
Chemical elements with face-centered cubic structure