Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement.

Copper is one of the few metals that can occur in nature in a directly usable metallic form (native metals). This led to very early human use in several regions, from c. 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, c. 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create bronze, c. 3500 BC. In the Roman era, copper was mined principally on Cyprus, the origin of the name of the metal, from aes cyprium (metal of Cyprus), later corrupted to cuprum (Latin). Coper (Old English) and copper were derived from this, the later spelling first used around 1530. Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as azurite, malachite, and turquoise, and have been used widely and historically as pigments.

Copper used in buildings, usually for roofing, oxidizes to form a green patina of compounds called verdigris. Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as bacteriostatic agents, fungicides, and wood preservatives.

Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the iron-complexed hemoglobin in fish and other vertebrates. In humans, copper is found mainly in the liver, muscle, and bone. The adult body contains between 1. 4 and 2. 1 mg of copper per kilogram of body weight.

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Atomic properties

Standard atomic weight63.546 ±0.003
Atomic mass63.5463 u

Atomic radii

Radius (empirical)128 pm
Radius (calculated)145 pm
Covalent radius132 ±4 pm
Van der Waals radius140 pm

Atomic shell

Electron configurationAr 3d10 4s1
Ionization energy(1st) 7.72638 eV
(2nd) 20.29239 eV
(3rd) 36.841 eV
(4th) 57.38 eV
(5th) 79.8 eV
Shell model

Physical properties

Density8.92 g·cm−3 (293.1 K)
Molar volume7.11·10-6 m3·mol−1
Speed of sound3,570 m·s−1


Melting point1,357 K
Boiling point2,835 K
Liquid range1,477 K


Melting enthalpy13.1 kJ·mol-1
Enthalpy of vaporization300 kJ·mol-1
Binding energy338 kJ·mol-1

Heat and conductivity

Specific heat capacity385 J·kg−1·K−1
Thermal conductivity400 W·m-1·K-1
Expansion coefficient1.65·10-5 K-1
Work function4.65 eV


Mohs hardness3
Brinell hardness874 NM·m-2
Vickers hardness369 NM·m-2

Elastic properties

Young’s modulus130 GPa
Shear modulus48 GPa
Bulk modulus140 GPa
Poisson’s ratio0.34

Electrical properties

Electrical conductivity5.81·107 S·m-1
Resistance1.719·10-8 Ωm


Magnetic susceptibility-5.461·10-6 cm3·mol−1

Optical properties

Reflectivity90 %

Chemical properties

Basicityslightly basic
Oxidation state1, 2, 3, 4
Standard potential0.34 V (Cu2+ + 2e- → Cu)


Pauling scale1.9
Sanderson scale1.98
Allred-Rochow scale1.75
Mulliken scale1.49
Ghosh-Gupta scale4.002 eV
Nagle scale1.51
Pearson absolute negativity4.48 eV

Other properties

Natural occurrenceprimordial
Crystal structureFace-centered cubic
Goldschmidt Classificationchalcophile
Superconductorwithout transition tempperature
Price/kg6 USD

Natural abundances

60 ppb ≈ 6.03·1011 M☉
700 ppb ≈ 1.39·1012 Mt
110,000 ppb ≈ 110 g
Earth’s crust
68,000 ppb ≈ 1.88·106 Mt
3 ppb ≈ 4.11 Gt
Flowing water
6 ppb ≈ 96 kt
Human body
1,000 ppb ≈ 70 mg