Copper (Cu)

Copper is a transition metal with atomic number 29, in period 4 and group 11 of the periodic table. Its atomic mass is 63.546 u and its electron configuration is [Ar] 3d¹⁰ 4s¹. Solid at 25 °C.

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Key facts

Atomic number	29
Atomic mass	63.546 u
Category	Transition Metal
Period	4
Group	11
Block	d
Electron configuration	[Ar] 3d¹⁰ 4s¹
Electrons per shell	2, 8, 18, 1
Electronegativity (Pauling)	1.9
Oxidation states	−2, −1, +1, +2, +3, +4common in bold
State at 25 °C	Solid
Melting point	1357.77 K1084.62 °C
Boiling point	2835 K2561.85 °C
Density	8.96 g/cm³

Atomic properties

First ionization energy	7.726 eV
Electron affinity	118.4 kJ/mol
Atomic radius	128 pm
Covalent radius	132 pm
Van der Waals radius	140 pm
Common ions	Cu²⁺, Cu⁺
Protons, neutrons, electrons	29, 35, 29

Physical and thermal properties

Molar volume	7.11 cm³/mol
Heat of fusion	13.1 kJ/mol
Heat of vaporization	300 kJ/mol
Specific heat	384.4 J/(kg·K)
Thermal conductivity	400 W/(m·K)
Thermal expansion	1.65 × 10⁻⁵ K⁻¹
Mohs hardness	3
Young’s modulus	130 GPa
Crystal structure	Face-centered cubic
Magnetic type	Diamagnetic

Identification and history

CAS number	7440-50-8
Latin name	Cuprum
Discovered by	Known since antiquity
Named by	---

Natural isotopes

Isotope	Mass (u)	Abundance
⁶³Cu	62.929597	69.15 %
⁶⁵Cu	64.927789	30.85 %

Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.

A dash (---) means there is no reliable published measurement. The app never makes one up.

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