Copper · element 29
The first metal humans worked, the wire in every wall, and the reason the Statue of Liberty is green
Key facts
Copper was the first metal people learned to hammer, shape and eventually melt, many thousands of years ago. It gave its name to the Copper Age and, mixed with tin, to the Bronze Age. Today it matters more than ever, because copper carries electricity better than any metal except silver, and the modern world runs on wires.
Its warm reddish-orange colour makes copper, alongside gold, one of only two everyday metals with a distinct colour. That colour comes from the way copper's electrons absorb blue light, a direct consequence of its electronic structure.
Where it is found
Copper occasionally occurs as pure nuggets, which is how prehistoric people first found it, most famously around Lake Superior in North America. Most copper today comes from low-grade sulfide ores such as chalcopyrite and bornite, and from oxidised ores like green malachite and blue azurite. Chile is the largest producer, with Peru, the Democratic Republic of the Congo, China and the United States also important. The open pits at Chuquicamata in Chile and Bingham Canyon in Utah are among the largest holes ever dug.
Typical ores contain well under one per cent copper, so vast amounts of rock are moved for each tonne of metal. Copper is essential to life. It sits in enzymes that handle oxygen and make pigment, and in the blue blood of octopuses and crabs, which use a copper protein called haemocyanin instead of iron-based haemoglobin.
How it was discovered
Copper has no discoverer. Beads and awls of hammered native copper appear in the Middle East around 8000 BC, and smelting from ore was under way by about 5000 BC. The Latin name cuprum comes from Cyprus, a major source for the Roman world, and is the origin of the symbol Cu. By the third millennium BC people had found that adding tin made bronze, which is harder and easier to cast, and bronze tools and weapons dominated for two thousand years until iron took over. The Iceman known as Ötzi, who died in the Alps about 5300 years ago, carried a copper axe.
What we use it for
Roughly 60 per cent of copper goes into electrical uses: wiring in buildings, windings in motors and generators, power cables, transformers and the printed circuit boards inside electronics. A typical petrol car contains around 20 kilograms of copper; an electric car contains several times more, and wind turbines and solar farms need large amounts too. Copper pipes carry water in homes because they are easy to join and resist corrosion.
Copper alloys are everywhere. Brass, copper with zinc, makes taps, musical instruments and door handles. Bronze, copper with tin, makes bells, statues and ship propellers. Copper-nickel alloys make coins. Copper surfaces kill bacteria on contact, so they are used for door handles and bed rails in some hospitals, and copper compounds are sprayed on vines to prevent fungal disease. Copper sulfate is the bright blue crystal of school chemistry lessons.
Reading the numbers
Copper melts at about 1085 °C, low enough for early furnaces and far below iron, which is one reason it was used first. It boils at about 2562 °C. Its density of 8.96 g/cm³ is greater than iron's. The configuration [Ar] 3d10 4s1 is the key to copper: a full d shell plus one loosely held s electron. That lone electron moves freely through the metal, giving copper its outstanding conductivity of heat and electricity, and it is lost easily to form Cu+. Copper also forms Cu2+, the blue-green ion of most copper salts. The full d shell places copper with silver and gold, its neighbours in group 11, often called the coinage metals. All three are relatively unreactive, ductile and coloured or lustrous. Copper's first ionisation energy of 745 kJ per mole is modest, but its second is much higher because it means breaking into the stable d shell.
Safety and the environment
Copper is essential in small amounts and toxic in large ones, though poisoning is rare because excess copper causes vomiting before much is absorbed. Wilson's disease is a genetic disorder in which copper builds up dangerously in the liver and brain. Copper is far more toxic to aquatic life, algae and fungi than to people, which is why it is used in antifouling paints and fungicides, and also why runoff from mines and vineyards can harm streams. Copper mining produces large volumes of tailings and acidic drainage. On the positive side, copper is one of the most recycled of all metals: recycling needs far less energy than mining and the metal loses nothing in the process.
Did you know?
- The Statue of Liberty is clad in copper sheet, and its green colour is a protective layer of copper carbonates and sulfates that formed within a few decades of its unveiling.
- Octopus and crab blood is blue because it carries oxygen with a copper protein, haemocyanin, rather than iron-based haemoglobin.
- Copper kills bacteria and viruses on contact, an effect the ancient Egyptians exploited by storing water in copper vessels.
- Among all metals only silver conducts electricity better than copper, and silver is far too expensive for wiring.
- Because copper is so easily recycled, a large share of all the copper ever mined is still in use today.
- Ötzi, the 5300-year-old Iceman found in the Alps, carried a copper axe, showing that copper smelting was already established in Europe.
More in the transition metals
Column-mates come first, since elements in one column have outer electrons arranged in a similar way and tend to behave alike; the rest are the nearest neighbours in the family.
See all 38 transition metals on one page, or browse all 118 elements.
Compare Copper with another element
Each comparison has a side-by-side data table and a plain-English summary of the differences.
Frequently asked questions
Why does copper turn green?
Exposed to air, rain and pollution, copper slowly reacts to form a thin layer of green copper carbonates and sulfates called a patina. Unlike rust on iron, the patina is stable and protects the metal beneath, which is why copper roofs last for centuries.
Why is copper used for electrical wires?
Copper conducts electricity better than every metal except silver, it is soft enough to draw into fine wire, and it resists corrosion. Aluminium is lighter and cheaper and is used for overhead power lines, but copper wins for wiring inside buildings and machines.
Is copper magnetic?
No. Copper is very weakly diamagnetic, meaning it is slightly repelled by a magnet, but the effect is far too small to notice. A moving magnet does, however, induce currents in copper, which is why a magnet dropped through a copper pipe falls slowly.
Is copper safe for drinking water pipes?
Yes. Copper pipes have been used for decades and release only tiny amounts of copper into water, well within safety limits, and copper actually helps suppress bacteria in the pipes. Very soft or acidic water can dissolve more copper, and the first water run from a tap after standing overnight carries the most.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Copper reference article. Spotted an error? Tell us.