Copper (Cu)

Reddish-orange metal

Copper is the best conductor of electricity after silver, turning Statue-of-Liberty green with time, and with the anomalous [Ar] 3d¹⁰ 4s¹ configuration (full d-shell stability), copper has the highest electrical conductivity of any metal and the second-highest thermal conductivity. Its green patina is copper carbonate.

Key metrics

Density8.96g/cm³

Melting point1,357K

Boiling point2,835K

Electronegativity1.9Pauling

Discovery

-9000discovered

Discovered by: Ancient civilizations
Reactivity profile: Forms protective patina
Reactivity: Low
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Ar]}\; \textcolor{#22c55e}{3_{d}^{10}}\; \textcolor{#ef4444}{4_{s}^{1}}

[Ar] 3d10 4s1

Wave function

\Psi_{\text{Cu}} \approx \frac{1}{\sqrt{29!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{29}(\mathbf{r}_{29}) \right|

Probability density $|\Psi|^2$ across the Cu valence shell.

Crystal structure

Face-Centered Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 128 pm
Ionization energy: 745 kJ/mol
Electron affinity: 119 kJ/mol
Crystal structure: Face-centered cubic (fcc)

Oxidation states

+1+2

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1357 K2835 K298 K

Emission spectrum

4 transitions

380450500550600650700780

VioletBlueGreenYellowRed

510.6nmCu IGreen80%

515.3nmCu I (green)Green100%

521.8nmCu I (green)Green50%

570.0nmCu II (yellow)Yellow60%

Dominant line 515.3 nmRange 511–570 nmTransitions 4