|
Copper (Cu)
| 29 |
nickel ← copper → zinc |
-
↑
Cu
↓
Ag |
|
Periodic table
- Extended periodic
table | | |
| 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] 4s1 3d10 |
| 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
(2567 °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 3.6149 Å |
| 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: 3666 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 |
| 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 | |
|
|
| Copper 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 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 mankind, which has
used the easily accessible uncompounded metal for thousands of years.
Civilizations in places such as Iraq, China, Egypt, Greece, India and the
Sumerian cities all 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, though high demand
relative to supply has caused a price spike in the 2000s.
Notable
Characteristics
Conductivity
Copper has a high electrical and thermal conductivity, second only to silver
among pure metals at room temperature.
Color
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.
Location in the periodic table
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.
Corrosion properties
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
copper oxide on copper metal.
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.
|
The Pourbaix diagram for copper in pure
water, perchloric acid or sodium
hydroxide |
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
can often be seen.
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 |
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.
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 doesn't contain the ammonia.
The Pourbaix diagram for copper in a
sulfide containing aqueous medium |
The Pourbaix diagram for copper in 10 M
ammonia solution |
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 |
Mechanical Properties
Single Crystal Copper
A single crystal copper consists of a few microns 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
Polycrystal copper (a) 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.
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.
Alloys
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.
This effect is useful in many applications.
Applications
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:
Native copper specimen (~ 4 cm in
size) |
Piping
- including, but not limited to, extreme
water supply.
Electronics
- Electromagnets.
- Printed circuit boards.
- Lead free solder, alloyed with tin.
Copper piping system with intumescent firestop being
installed by an insulator in Vancouver,
Canada. |
- Electrical machines, especially electromagnetic
motors, generators and transformers.
- Electrical relays, electrical busbars and
electrical switches.
- Vacuum tubes, cathode ray tubes, and the
magnetrons in microwave ovens.
- Wave guides for microwave radiation.
- Integrated circuits, increasingly replacing
aluminium because of its superior electrical conductivity.
- As a material in the manufacture of
computer heat sinks, as a result of its superior heat dissipation capacity to
aluminium.
- Copper Wire
Architecture
Copper roof on the Minneapolis City Hall,
coated with Patina |
- Copper has been used as water-proof roofing
material since ancient times, giving many old buildings their greenish roofs and
domes. Initially copper oxide forms, replaced by cuprous and cupric sulfide, and
finally by copper sulfate. The final sulfate patina is highly resistant to
corrosion.
- Statuary: The Statue of Liberty, for example,
contains 179,220 pounds (81.3 tonnes) of copper.
- Alloyed with nickel, e.g. cupronickel and Monel,
used as corrosive assistant materials in shipbuilding.
- Watt's steam engine.
Household products
Old copper utensils in a Jerusalem
restaurant |
- Copper plumbing fittings and compression tubes.
- Doorknobs and other fixtures in houses.
- Roofing, guttering, and
rainspouts on buildings.
- In cookware, such as frying pans.
- Most flatware (knives, forks, spoons) 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
Coinage
- As a component of coins, often as cupronickel
alloy.
- Coins in the following countries all contain
copper: European Union (Euro), United States, UnitedKingdom (sterling),
Australia and New Zealand.
- Ironically, U.S. Nickels are 75.0% copper by
weight and only 25.0% nickel.
Biomedical applications
- As a biostatic surface in hospitals, and to line parts of
ships to protect against barnacles and mussels, originally used pure, but superseded by Muntz
Metal. Bacteria will
not grow on a copper surface because it is biostatic. Copper doorknobs are used by hospitals to reduce the transfer of disease, and
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 glazes, and to color
glass.
Other
- Musical instruments,
especially brass instruments 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.
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. 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. Copper is found
extensively in the Indus Valley Civilization by the 3rd millennium BC. 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. 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
between 6000 to 3000 BC.
By 2000 BC, Europe was using copper-tin alloys or 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 was known to the Greeks, but only became
a significant supplement to bronze during the Roman empire.
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.
Britain and Ireland
West Mine at Alderley
Edge |
During the Bronze Age, copper was mined in Britain and Ireland mainly in the
following locations:
- South West County Cork
- West Wales (e.g. Cwmwystwyth)
- North Wales (e.g. Great Orme)
- Anglesey (Parys Mountain)
- Cheshire (Alderley Edge)
- The Staffordshire Moorlands (e.g. Ecton Mine)
- Isle of Man, which is between England and Northern Ireland
At Great Orme in North Wales, such working extended for a depth of 70 metres.
At Alderley Edge in Cheshire, carbon dates have established mining at around
2280 to 1890 BC (at 95% probability).
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 CE. 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 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. Copper is the state mineral for Utah.
Occurence and
modern industry
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.
Chuquicamata (Chile). One of the largest
open pit copper mines in the world. |
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.
Native
Copper Placer Nuggets | 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
$0.60 per pound in June 1999 to $3.75 per pound in May 2006, where it dropped to
$2.40 in February 2007 then rebounded to $3.50 in April 2007.
The Earth has an estimated 61 years of copper reserves
remaining.
By: Zookeeper - 2007-12-01 19:00:48
|
RSS Feed
