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29 nickel ← copper → zinc
-
↑
Cu
↓
Ag
General
Name, Symbol, Number copper, Cu, 29
Chemical series transition metals
Group, Period, Block 11, 4, d
Appearance metallic pinkish red
Standard atomic weight 63.546(3) g·mol−1
Electron configuration [Ar] 3d10 4s1
Electrons per shell 2, 8, 18, 1
Physical properties
Phase solid
Density (near r.t.) 8.96 g·cm−3
Liquid density at m.p. 8.02 g·cm−3
Melting point 1357.77 K
(1084.62 °C, 1984.32 °F)
Boiling point 2835 K
(2562 °C, 4643 °F)
Heat of fusion 13.26 kJ·mol−1
Heat of vaporization 300.4 kJ·mol−1
Heat capacity (25 °C) 24.440 J·mol−1·K−1
Vapor pressure
P/Pa 1 10 100 1 k 10 k 100 k
at T/K 1509 1661 1850 2089 2404 2836
Atomic properties
Crystal structure face centered cubic
Oxidation states 2, 1
(mildly basic oxide)
Electronegativity 1.90 (Pauling scale)
Ionization energies
(more)		 1st: 745.5 kJ·mol−1
2nd: 1957.9 kJ·mol−1
3rd: 3555 kJ·mol−1
Atomic radius 135 pm
Atomic radius (calc.) 145 pm
Covalent radius 138 pm
Van der Waals radius 140 pm
Miscellaneous
Magnetic ordering diamagnetic
Electrical resistivity (20 °C) 16.78 nΩ·m
Thermal conductivity (300 K) 401 W·m−1·K−1
Thermal expansion (25 °C) 16.5 µm·m−1·K−1
Speed of sound (thin rod) (r.t.) (annealed)
3810 m·s−1
Young's modulus 110 - 128 GPa
Shear modulus 48 GPa
Bulk modulus 140 GPa
Poisson ratio 0.34
Mohs hardness 3.0
Vickers hardness 369 MPa
Brinell hardness 874 MPa
CAS registry number 7440-50-8
Selected isotopes
Main article: Isotopes of copper
iso NA half-life DM DE (MeV) DP
63Cu 69.15% Cu is stable with 34 neutrons
65Cu 30.85% Cu is stable with 36 neutrons
References
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Copper exists as a metallically bonded substance, allowing it to have a wide variety of metallic properties.
Copper exists as a metallically bonded substance, allowing it to have a wide variety of metallic properties.

Copper (IPA: /ˈkɒpə/, /ˈkɑpəɹ/) is a chemical element in the periodic table that has the symbol Cu (Latin: cuprum) and atomic number 29. It is a ductile metal with excellent electrical conductivity, and finds extensive use as an electrical conductor, heat conductor, as a building material, and as a component of various alloys.

Copper is an essential 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. In sufficient amounts, copper can be poisonous and even fatal to organisms.

Copper has played a significant part in the history of mankind, which has used the easily accessible uncompounded metal for nearly 10,000 years. Civilizations in places like Iraq, China, Egypt, Greece and the Sumerian cities all have early evidence of using copper, Britain and the United States also have extensive histories of copper use and mining. 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 sizeable reserves of the metal which are extracted through large open mines. Nevertheless, the price of copper rose rapidly, increasing 500% from a 60-year low in 1999, largely due to increased demand. This metal has come into the limelight on account of high volatility in prices. According to New Scientist (May 26, 2007) the earth has an estimated 61 years supply of copper left.

Contents

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[edit] Notable characteristics

Copper just above its melting point keeps its pink luster color when enough light overshines the orange incandescence color.
Copper just above its melting point keeps its pink luster color when enough light overshines the orange incandescence color.

Copper is a reddish-colored metal, with a high electrical and thermal conductivity (silver is the only pure metal to have a higher electrical conductivity at room temperature).[1] In oxidation copper is mildly basic. Copper has its characteristic color because it reflects red and orange light and absorbs other frequencies in the visible spectrum, due to its band structure. This can be contrasted with the optical properties of silver, gold and aluminium.

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 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.

In its liquified state, a pure copper surface without ambient light appears somewhat greenish, another characteristic shared with gold. Silver does not have this property, so it is not a complementary color for the orange incandescence color. When liquid copper is in bright ambient light, it retains some of its pinkish luster. Due to its high surface tension, the liquid metal does not wet surfaces but instead forms spherical droplets when poured on a surface.

Copper is insoluble in water (H2O) as well as in isopropanol.

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.

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.

Copper is germicidal, via the oligodynamic effect. For example, brass doorknobs disinfect themselves of many bacteria within eight hours [1]. This effect is useful in many applications.

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 (eg 4N means 0.9999, or 99.99%).

[edit] Applications

Native copper specimen
Native copper specimen
Copper piping system in a building with intumescent firestop being installed by an insulator, Vancouver, British Columbia, Canada.
Copper piping system in a building with intumescent firestop being installed by an insulator, Vancouver, British Columbia, Canada.

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

It is used extensively, in products such as:

Copper roof on the Minneapolis City Hall, coated with Patina
Copper roof on the Minneapolis City Hall, coated with Patina
Old copper utensils in a Jerusalem restaurant
Old copper utensils in a Jerusalem restaurant
  • Coinage:
    • As a component of coins, often as cupronickel alloy.
    • Coins in the following countries all contain copper: European Union (Euro)[2], United States,[3] United Kingdom (sterling)[4] and Australia.[5]
    • Ironically, U.S. Nickels are 75.0% copper by weight and only 25.0% nickel.[3]

[edit] History

Copper is found extensively in the Indus Valley Civilization by the 3rd millennium BC.[6] Use of copper in ancient China dates to at least 2000 BC. By 1200 BC excellent bronzes were being made in China. (Note that these dates are affected by wars and conquest, as copper is easily melted down and reused). In Europe, Ötzi the Iceman, a well-preserved male dated to 3200 BC, was found with a copper-tipped axe whose metal was 99.7% pure. High levels of arsenic in his hair suggest he was involved in copper smelting. Brass, an alloy of zinc and copper, was known to the Greeks but first used extensively by the Romans.

There are 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 bronze alloys were found in Egypt almost as soon as copper was found. In the Americas production in the Old Copper Complex, located in present day Michigan and Wisconsin, was dated back to at least 6000 to 3000 BCE.[7]

In Greek times, the metal was known by the name chalkos (χαλκός). Copper was a very important resource for the Romans and Greeks and Spainish. 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. In alchemy the symbol for copper was also the symbol for the planet Venus.

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. A copper pendant was found in what is now northern Iraq that dates to 8700 BCE. By 5000 BCE, 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 BCE) features native copper artifacts and smelted lead beads, but no smelted copper. But Can Hasan (~5000 BCE) 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.
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 BCE, it was developed in China before 2800 BCE, in the Andes around 2000 BCE, in Central America around 600 AD, and in West Africa around 900 AD.[8]

The use of bronze was so pervasive in a certain era of civilization 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, with some high-purity copper tools being used alongside stone tools.

[edit] Copper mining in Britain and the United States

See Copper extraction for the article on copper mining techniques.

Copper has been mined for many centuries. By 2000 BC, Europe was using copper-tin alloys or ‘bronze’. The Bronze Age is taken as 2500 BC to 600 BC.

West Mine at Alderley Edge
West Mine at Alderley Edge

[edit] Britain & Ireland

During the Bronze Age, copper was mined in Britain & Ireland mainly in the following locations:

At Great Orme in North Wales, such working extended for a depth of 70 metres.[9] At Alderley Edge in Cheshire, carbon dates have established mining at around 2280 - 1890 BC (at 95% probability).[10]

[edit] United States

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

Copper mining in United States began with marginal workings by Native Americans and some development by early Spaniards. Europeans were mining copper in Connecticut as early as 1709. 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.

Copper was mined extensively in Michigan's Keweenaw Peninsula with the heart of extraction at the productive Quincy Mine. 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.

[edit] Biological role

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.[11]

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. Because of its role in facilitating iron uptake, copper deficiency can often produce anemia-like symptoms.

[edit] Toxicity

All copper compounds, unless otherwise known, should be treated as if they were toxic. Thirty grams of copper sulfate is potentially lethal in humans. 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. The DRI Tolerable Upper Intake Level for adults of dietary copper from all sources is 10 mg/day. In toxicity, copper can inhibit the enzyme dihydrophil hydratase, an enzyme involved in haemopoiesis.

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

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.

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.[12] 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.

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.

[edit] 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.

[edit] Occurrence

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