Erbium (Er)

Silvery white

Erbium is the element that makes fiber-optic internet possible, amplifying light signals across oceans, and with twelve 4f electrons, Er³⁺ has an emission at 1550 nm—exactly the minimum-loss wavelength of silica optical fiber. Erbium-doped fiber amplifiers (EDFAs) boost signals without electronic conversion, enabling global internet.

Key metrics

Density9.07g/cm³

Melting point1,802K

Boiling point3,141K

Electronegativity1.24Pauling

Discovery

1843discovered

Discovered by: Carl Gustaf Mosander
Reactivity profile: Slow oxidation
Reactivity: High
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Xe]}\; \textcolor{#a855f7}{4_{f}^{12}}\; \textcolor{#ef4444}{6_{s}^{2}}

[Xe] 4f12 6s2

Wave function

\Psi_{\text{Er}} \approx \frac{1}{\sqrt{68!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{68}(\mathbf{r}_{68}) \right|

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

Crystal structure

Hexagonal Close-Packed

Lattice constantsa 1.00 · b 1.00 · c 1.63

Cell anglesα 90° · β 90° · γ 120°

Coordination number12

Atoms per cell2

Atomic packing factor0.74

Physical properties

Atomic radius: 173 pm
Ionization energy: 589 kJ/mol
Electron affinity: 50 kJ/mol
Crystal structure: Hexagonal close-packed (hcp)

Oxidation states

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1802 K3141 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

522.6nmEr I (green)Green50%

538.8nmEr IGreen70%

552.7nmEr I (green)Green100%

Dominant line 552.7 nmRange 523–553 nmTransitions 3