Copper (Cu)

Copper (symbol Cu) is the chemical element with atomic number 29: a transition metal, solid at 0 °C, with an atomic mass of 63.546 u. Known since antiquity.

Copper is one of the few colored metals, with a distinctive reddish-orange hue. It was the first metal shaped by humankind, and was later alloyed with tin to make bronze. After silver, it is the best conductor of electricity, making it the metal of cables, motors and power grids. The energy transition has made it one of the most strategic raw materials.

Key facts

Atomic number: 29
Symbol: Cu
French name: Cuivre
Atomic mass: 63.546 u
Molar mass: 63.546 g/mol
Family: Transition metals
Position: period 4, group 11, d-block
State at 0 °C: Solid
Melting point: 1,084.6 °C
Boiling point: 2,561.9 °C
Density: 8.96 g/cm³
Electronegativity (Pauling): 1.9
First ionization energy: 745 kJ/mol
Atomic radius: 135 pm
Electron configuration: [Ar] 3d¹⁰ 4s¹
Abundance in Earth's crust: 60 ppm (26th most abundant element)
Indicative price: 6 $/kg (order of magnitude)
Radioactive: no
Discovery: Antiquity

Origin of the name

From the Latin cuprum, “metal of Cyprus,” which also gives the symbol Cu.

What does copper look like?

A shiny, reddish-orange, very ductile metal that tarnishes to brown and, after many years in damp air, develops a green patina (verdigris).

Where is copper found?

About 60 ppm of Earth's crust. It sometimes occurs in native form, but comes mainly from large sulfide deposits (porphyry copper). The human body contains about 70 to 100 mg.

Natural sources

Chalcopyrite
Chalcocite
Bornite
Malachite
Azurite
Native copper

How is copper produced?

Sulfide ores are concentrated, smelted, then refined by electrolysis to 99.99% purity; oxide ores are dissolved in acid. Mine production exceeds 22 million tonnes a year, and about a third of the copper used comes from recycling.

Top producers

Chile
Peru
Democratic Republic of the Congo
China

What is copper used for?

Electrical cables and wires.
Motors, transformers and generators.
Plumbing and heating.
Alloys: bronze, brass, cupronickel.
Electronics (circuit boards, chips).
Agricultural fungicide (Bordeaux mixture).

In everyday life

The electrical wiring in your home
Plumbing pipes
1, 2 and 5 euro cent coins (copper-plated steel)
Your phone charger
Copper pans

Role in living things

Essential: it is part of enzymes involved in cellular respiration and in making collagen and melanin. In octopuses, spiders and horseshoe crabs, hemocyanin, a copper protein, carries oxygen and turns the blood blue. Wilson's disease, a genetic disorder, prevents the body from getting rid of copper.

Hazards of copper

The metal is of low toxicity, but its soluble salts (copper sulfate) are toxic at high doses. It is highly toxic to aquatic life and builds up in vineyard soils treated for more than a century.

Cosmic origin

Supernovae: Forged in the cores of massive stars, then scattered when they explode.

History of copper

Beads of hammered native copper dating back more than 10,000 years have been found in the Near East. Smelting ore appeared around 5000 BCE, and the Bronze Age began around 3300 BCE. The Romans got their copper from Cyprus, hence the Latin cuprum and the symbol Cu.

Did you know?

The Statue of Liberty is clad in copper sheets about 2.4 mm thick; its green color is a patina that formed in about thirty years.
Ötzi, the Iceman who died about 5,300 years ago in the Alps, carried an axe with a blade of almost pure copper.
An electric car contains about three to four times as much copper as a gasoline car.

Isotopes of copper

Two stable isotopes, copper-63 and copper-65. Copper-64, a rare isotope capable of all three kinds of beta decay, is a tool of nuclear medicine.

copper-63: 69.15% of natural copper, stable
copper-64: radioactive, half-life 12.7 h. PET imaging of tumors and research into copper metabolism disorders.
copper-65: 30.85% of natural copper, stable
copper-67: radioactive, half-life 2.58 days. Candidate for targeted cancer radiotherapy.

Common compounds

Malachite (Cu₂CO₃(OH)₂)

Related elements

Same family (transition metals): Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Zinc (Zn), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au), Mercury (Hg), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs).

Same column (group 11): Silver (Ag), Gold (Au), Roentgenium (Rg).