Holmium (Ho)

Silvery white

Holmium has the highest magnetic moment of any naturally occurring element, used in the strongest magnets, and with eleven 4f electrons, Ho³⁺ has a magnetic moment of 10.6 μB—the highest of any element. Holmium-doped YAG lasers (2.1 μm wavelength) are used in medical procedures and as wavelength references.

Key metrics

Density8.8g/cm³

Melting point1,734K

Boiling point2,873K

Electronegativity1.23Pauling

Discovery

1878discovered

Discovered by: Marc Delafontaine
Reactivity profile: Oxidizes slowly
Reactivity: High
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Xe]}\; \textcolor{#a855f7}{4_{f}^{11}}\; \textcolor{#ef4444}{6_{s}^{2}}

[Xe] 4f11 6s2

Wave function

\Psi_{\text{Ho}} \approx \frac{1}{\sqrt{67!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{67}(\mathbf{r}_{67}) \right|

Probability density $|\Psi|^2$ across the Ho 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: 174 pm
Ionization energy: 581 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

1734 K2873 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

451.5nmHo I (blue)Blue40%

535.5nmHo I (green)Green100%

540.8nmHo IGreen70%

Dominant line 535.5 nmRange 452–541 nmTransitions 3