Copper (Cu)
Element 29 · Transition metal · atomic mass 63.546 u · group 11, period 4
Electron shells: 2, 8, 18, 1
Copper was the first metal humans worked, and it remains second only to silver in electrical conductivity. Alloyed with tin it gave the Bronze Age its name.
Bacteria die on bare copper surfaces within hours — hospitals use it on door handles for that reason.
- Atomic number
- 29
- Atomic mass
- 63.546 u
- Electron configuration
- [Ar] 4s¹ 3d¹⁰
- Group · period · block
- 11 · 4 · d
- Oxidation states
- +1, +2
- Electronegativity
- 1.9 (Pauling)
- Melting point
- 1,085 °C
- Boiling point
- 2,562 °C
- Density
- 8.933 g/cm³
- State at 20 °C
- Solid
- Appearance
- Reddish-orange metal
- Discovered
- Known since antiquity
29 protons, and 29 electrons when neutral
IUPAC standard atomic weight
Coinage metals
What Copper is used for
- Electrical wiring and motors
- Plumbing and roofing
- Brass and bronze alloys
- Antimicrobial touch surfaces
Atomic structure of Copper
A neutral copper atom has 29 protons and 29 electrons. Its most common isotope carries about 35 neutrons, which is where the mass number 64 comes from. Change the neutron count and you have a different isotope of copper; change the proton count and you have a different element entirely.
Those electrons fill shells from the inside out: 2, 8, 18, 1. In orbital notation that is [Ar] 4s¹ 3d¹⁰. As a d-block element its valence count is variable, which is why it can form compounds in several oxidation states.
3D electron orbitals
See where Copper's electrons actually are — a cloud of 26,000 points sampled from the probability density |ψ|², not a cartoon of a lobe.
Where Copper sits in the periodic table
Discovery and naming
Copper has been known and used since antiquity, long before anyone could describe it as an element. Its name comes from Latin cuprum, from Cyprus, which is also why its symbol (Cu) does not match its English name.
Keep exploring
Atomic weight from IUPAC/CIAAW; physical properties from PubChem (US National Library of Medicine). Values that have never been measured are shown as “not measured” rather than estimated.
Related Calculators
Frequently Asked Questions
What is the atomic mass of Copper?
The standard atomic weight of Copper is 63.546 u, as published by IUPAC's Commission on Isotopic Abundances and Atomic Weights.
How many protons, neutrons and electrons does Copper have?
Copper has 29 protons, because the atomic number is the proton count and that is what makes an atom Copper at all. A neutral Copper atom has the same number of electrons, 29. The neutron count varies by isotope; the most common one has about 35, since 64 − 29 = 35.
What is the electron configuration of Copper?
The electron configuration of Copper is [Ar] 4s¹ 3d¹⁰. Its electrons are arranged 2, 8, 18, 1 across 4 shells.
Is Copper a metal?
Yes. Copper is classified as a transition metal, on the metallic side of the table.
What group and period is Copper in?
Copper is in group 11 (the coinage metals), period 4, in the d-block. The group is its column and the period is its row.
What is the charge of Copper?
Copper most commonly forms a 2+ or 1+ ion. Like most transition metals it has several accessible oxidation states, so the charge depends on the compound.
What is the melting point of Copper?
Copper melts at 1,085 °C and boils at 2,562 °C. That puts it in the solids at everyday temperatures.
What is Copper used for?
Electrical wiring and motors, Plumbing and roofing, Brass and bronze alloys, Antimicrobial touch surfaces. Copper was the first metal humans worked, and it remains second only to silver in electrical conductivity.
Who discovered Copper, and where does its name come from?
Copper (Cu) has been known and used since antiquity, long before anyone could describe it as an element. The name comes from Latin cuprum, from Cyprus.