Copper facts for kids

Some small pieces of copper in a tube. Recently processed copper is a pink color. The color changes to the more familiar orange when it reacts with air.

Copper

Copper is a chemical element. It is the 29th element in the periodic table. Its mass number is 63.55. It is a transition metal in the middle of the periodic table. The symbol for copper is "Cu", which comes from the Latin word cuprum, which, in turn, came from the Latin word for the island of Cyprus, where copper was found.

Properties

Physical properties

Copper disc, acid etched, you see the normally invisible crystalline structure

Copper is a reddish-orange color when it is pure, but soon gets a reddish tarnish after it is exposed to air.

Copper is one of the few coloured metals. Most metals are gray or silver. Gold, copper, caesium and osmium are the only four coloured metals. Copper is green as copper(II) carbonate and copper(II) hydroxide. It turns green because it oxidises. After a time in the air, copper forms green copper carbonate at the surface, called verdigris. That is why the copper roof of a building looks green.

Copper is very flexible and ductile. It can be stretched into wires easily. Copper is also very soft, it has a Mohs hardness of 2.5 to 3. That means that it is harder than a fingernail but softer than a steel pocketknife.

It reacts with solutions of hydrochloric acid or ammonia containing oxygen. It can also dissolve in a mixture of hydrogen peroxide and hydrochloric acid. This makes copper(II) chloride. It does not dissolve in weak acids. It can dissolve in nitric acid to make copper(II) nitrate and nitrogen dioxide or nitric oxide.

Compounds

Copper forms chemical compounds. In these compounds, it has two normal oxidation states: +1 and +2. +2 is more common. Most +2 copper compounds are blue. +1 copper compounds can be white. Copper compounds are weak oxidizing agents. They corrode many metals. This corrosion takes the metal and puts it in the chemical compound, leaving the copper behind. An example would be iron and copper(II) sulfate reacting to make copper and iron(II) sulfate. +1 copper compounds are reducing agents when in air. They are normally made by reduction of +2 compounds.

Copper compounds can be black, green, reddish, white, blue, or yellow.

Copper(I) compounds

Copper(I) compounds have copper in +1 oxidation state. They are weak reducing agents. They react with air to make copper(II) compounds. They also disproportionate to copper and copper(II) compounds. Most of them do not dissolve in water.

• Copper(I) acetylide, reddish brown, explosive
• Copper(I) bromide
• Copper(I) chloride, white when pure, green when oxidized
• Copper(I) iodide, colorless solid
• Copper(I) oxide, reddish-brown

Copper(II) compounds

Copper(II) compounds have copper in +2 oxidation state. They are weak oxidizing agents. They are greenish when hydrous (water molecules added). They are more stable in air than copper(I) compounds.

• Copper(II) bromide, gray solid
• Copper(II) carbonate, greenish, forms on copper when in air
• Copper(II) chloride, greenish when hydrous, brown when anhydrous
• Copper(II) hydroxide, light blue, turns into copper(II) carbonate easily
• Copper(II) nitrate, blue, oxidizing agent, used in demonstration voltaic cells
• Copper(II) oxide, black
• Copper(II) sulfate, blue, most common copper compound
• Paris Green, extremely toxic, bright blue-green

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  Copper(II) sulfate, a copper(II) compound

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  Copper(II) chloride, a copper(II) compound

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  Copper(I) chloride, a copper(I) compound. It is white but air reacts with it easily to turn it green

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  Copper(I) oxide, a copper(I) compound

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  Copper(II) oxide, a copper(II) compound

Occurrence

Copper as a metal in the ground

Chalcopyrite

Copper can be found as a metal in the ground. Normally, it is green on the outside. Most copper is not as a metal but in chemical compounds. Chalcopyrite is the most common copper ore. It is a mixture of pyrite and copper sulfide. Copper is found in small amounts in living things. Some mollusks and arthropods have blue blood because they have copper in their blood. Animals such as humans and other mammals have red blood because it contains iron.

Uses

Copper can be used in many ways but one example is wires. Copper is used in making wires as it is easy to stretch and it is not expensive. So that’s why large wire companies will use copper as it is cheaper and takes less time to get

Copper may be the oldest metal in use, as very old copper tools have been found. Copper is used in electrical wiring. It can also be shaped into various parts. It can be used in a heat sink. The Statue of Liberty is made of copper. It is also used in pipes carrying water, because it does not corrode.

When people mix copper with tin, bronze is made. Bronze is much harder, and created the Bronze Age. It became less important when people learned to use iron better. When zinc is mixed with copper, brass is made, which is even harder than bronze. Copper with nickel makes cupronickel.

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.

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.

The U.S. Institute of Medicine (IOM) updated the estimated average requirements (EARs) and recommended dietary allowances (RDAs) for copper in 2001. 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.

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 as of May 27,  2016 (2016 -05-27)^[update], 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, 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.

Safety

Copper is not as toxic as a metal. Copper compounds are toxic, although small amounts are needed to live. Copper is expelled from the body easily, so it does not build up in toxic effects.

Preparation

Copper is sometimes just taken out of the ground and shaped into objects. But most copper is not in a metal form in the ground. Chalcopyrite is the main copper ore. It is heated with air to separate the iron as iron(II) oxide. Some copper(I) oxide is made. Sulfur dioxide is also made. Then silicon dioxide is added, which reacts with the iron(II) oxide to make a liquid which is drained. Now only copper and sulfide are left. The copper sulfide reacts with air to make copper metal and sulfur dioxide. Some copper sulfide reacts with the copper(I) oxide to make copper and sulfur dioxide. This makes impure copper.

Copper is made pure by electrolyzing it. A thin sheet of pure copper is put on the cathode and a thick sheet of impure copper is put on the anode. The electrolyte is copper sulfate. The impure copper gets dissolved in the solution. It then coats the thin sheet of pure copper. This makes the copper pure.

Large amounts of copper are recycled because of its high value and the increasing depletion of worldwide copper reserves.

Recycling

Like aluminium, 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 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 in a bath of sulfuric acid.

Related pages

• Copper compounds

Images for kids

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

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  Unoxidized copper wire (left) and oxidized copper wire (right)

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  The East Tower of the Royal Observatory, Edinburgh, showing the contrast between the refurbished copper installed in 2010 and the green color of the original 1894 copper.

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  Native copper from the Keweenaw Peninsula, Michigan, about 2.5 inches (6.4 cm) long

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  Chuquicamata, in Chile, is one of the world's largest open pit copper mines

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  Copper prices 2003–2011 in US$ per tonne

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  Copper alloys are widely used in the production of coinage; seen here are two examples - post-1964 American dimes, which are composed of the alloy cupronickel and a pre-1968 Canadian dime, which is composed of an alloy of 80 percent silver and 20 percent copper.

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  Copper(II) gives a deep blue coloration in the presence of ammonia ligands. The one used here is tetraamminecopper(II) sulfate.

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  Ball-and-stick model of the complex [Cu(NH3)4(H2O)2]2+, illustrating the octahedral coordination geometry common for copper(II).

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  A corroded copper ingot from Zakros, Crete, shaped in the form of an animal skin (oxhide) typical in that era.

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  Many tools during the Chalcolithic Era included copper, such as the blade of this replica of Ötzi's axe

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  Copper ore (chrysocolla) in Cambrian sandstone from Chalcolithic mines in the Timna Valley, southern Israel.

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  Chalcolithic copper mine in Timna Valley, Negev Desert, Israel.

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  Copper Ornaments

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  Acid mine drainage affecting the stream running from the disused Parys Mountain copper mines

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  18th-century copper kettle from Norway made from Swedish copper

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  Chalcography of the city of Vyborg at the turn of the 17th and 18th centuries. The year 1709 carved on the printing plate.

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  Copper fittings for soldered plumbing joints

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  Copper electrical busbars distributing power to a large building

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  Copper roof on the Minneapolis City Hall, coated with patina

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  Old copper utensils in a Jerusalem restaurant

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  Large copper bowl. Dhankar Gompa.

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

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  Photosynthesis functions by an elaborate electron transport chain within the thylakoid membrane. A central link in this chain is plastocyanin, a blue copper protein.

See also

In Spanish: Cobre para niños