Chemical element · reference page

29Cu

Copper

Copper is element 29 (Cu), located in period 4, group 11 and the d block. At room temperature its reference phase is solid. Its electron configuration is [Ar] 3d10 4s1.

Atomic number29

Standard atomic weight63.546(3)

Group11

Period4

Blockd

Electron configuration[Ar] 3d10 4s1

Electronic structure

What controls its chemistry

The d subshell participates in the chemistry of copper. Transition metals can use electrons of similar energies in bonding, which is why variable oxidation states, coordination compounds and catalytic behaviour are common across the d block.

Its electron configuration, [Ar] 3d10 4s1, should be read together with the oxidation state of the compound: removing electrons changes which d orbitals are occupied and can alter colour, magnetism, bonding and reactivity.

Chemical forms

Compounds, ions and materials

For copper, important chemical forms include metals and alloys, oxides, halides and coordination compounds. Variable oxidation states are common because s and d electrons have similar energies, and ligands around the metal ion can strongly alter colour, magnetism and reactivity.

Physical behaviour

State and phase changes

The reference phase at room temperature is solid. The listed density is 8.96 g/cm³. The melting point is 1 358 K (1 085 °C). The boiling point is 2 835 K (2 562 °C). Pressure, purity and crystal structure can shift measured physical properties.

Occurrence and applications

Where copper is found and used

In practice, copper is encountered in electrical wiring, plumbing and electronics.

In practice

Examples of real uses

Electrical wiring

Copper is used as a conductor because it combines high electrical conductivity with workable mechanical properties.

Plumbing

Copper is used in pipes, fittings or corrosion-resistant plumbing materials.

Electronics

Copper is used in electronic components or materials where conductivity, semiconducting behaviour, optical response or chemical stability is useful.

Periodic position

What its neighbours tell us

Copper is in period 4 and group 11. In the neighbourhood shown here, it lies between nickel and zinc in the same period; silver is directly below it in the same group. These positions make it possible to compare atomic size, ionisation energy and bonding behaviour with nearby elements.

Reference data

Physical and atomic properties

Classificationtransition metal

Phase at room temperatureSolid

Electron shells2 · 8 · 18 · 1

Density8.96 g/cm³

Melting point1 358 K (1 085 °C)

Boiling point2 835 K (2 562 °C)

Pauling electronegativity1.9

First ionisation energy745.5 kJ/mol

Electron affinity119.2 kJ/mol

Values describe the element or neutral atom where applicable. Physical data can depend on allotrope, pressure and measurement conditions.

History

Discovery and identification

Early use of copper is associated with the Middle East. That is not a single modern discovery event: early use, chemical identification and the later atomic-number definition belong to different stages.

Isotopes and atomic weight

How isotope composition changes the numbers

The standard atomic weight is 63.546(3). This value refers to the isotopic composition of natural terrestrial material, not to the mass of one specific atom.

Copper has at least one stable isotope. Different isotopes have the same number of protons and therefore the same element identity, but different neutron numbers and atomic masses.

Safety

Handling and exposure

The hazards associated with copper depend on chemical form, dose and route of exposure. Pure copper, its ions and its compounds can have very different biological and environmental effects, so safety data should be checked for the actual substance being handled.