Copper

01 / A closer look

Meet Copper

Copper has atomic number 29: every atom of this element contains 29 protons. It belongs to period 4, group 11 of the periodic table.

In a neutral atom, the number of electrons equals the number of protons. Isotopes of this element share the same atomic number but have different neutron counts.

02 / Physical properties

Melting point

1357.77 K

Boiling point

2833 K

Density

8.96 g/cm³

Atomic weight

63.546 ± 0.003

Melting points, boiling points and densities follow RSC fact boxes. Density is referenced to room temperature; consult the source for pressure and allotrope details. These are reference values, not a claim that every value was experimentally measured. Atomic weights follow CIAAW.

Physical-property source: Royal Society of Chemistry ↗ · Reviewed 24 September 2026

Standard atomic weights follow CIAAW 2024 (abridged). Brackets show an isotope mass number from IUPAC 2022, not a standard atomic weight.

03 / Atomic structure

Atomic structure

Electron configuration

[Ar]4s1 3d10

Oxidation states

+2, +1

Electronegativity · Pauling

1.9

First ionisation energy

7.726 eV

Atomic radius

140 pm

04 / Where it is found

Where it is found

Chalcopyrite, bornite and some native copper deposits.