Holmium
lanthanideProperties
| Property | Value |
|---|---|
| Atomic Mass | 164.93 amu |
| Category | lanthanide |
| Period | 6 |
| Electron Configuration | [Xe] 4f11 6s2 |
| Electronegativity | 1.23 (Pauling) |
| Oxidation States | 3 |
| Melting Point | 1734 K (1460.8 °C) |
| Boiling Point | 2993 K (2719.8 °C) |
| Density | 8.79 g/cm³ |
| Discovered By | Jacques-Louis Soret, Marc Delafontaine (1878) |
About Holmium
Holmium has the largest atomic magnetic moment of any element in the table — 10.6 μ_B, coming from four unpaired 4f electrons coupled with significant orbital angular momentum. That's why pole pieces in the highest-field research magnets get capped with holmium-iron alloys: the moment lets you concentrate flux beyond what plain iron can sustain. The other lab-relevant fact about Ho is its absorption spectrum. Ho³⁺ in glass or perchloric-acid solution gives a series of sharp, narrow f-f bands that don't shift with temperature, which is why a holmium oxide solution cuvette is the official NIST wavelength standard for UV-Vis spectrophotometers from about 240 to 640 nm. Clinically, the Ho:YAG laser at 2.1 µm hits a strong water absorption peak, so it ablates kidney stones and prostate tissue with shallow penetration and minimal collateral damage.
Fun Fact
Holmium has the strongest magnetic moment of any element — if you could magnetize a chunk of pure holmium, it would create a stronger field per atom than any other element on the periodic table.
Common Uses
- Pole tips in high-field research electromagnets to concentrate flux
- Ho³⁺ solution cuvettes as NIST wavelength calibration standards
- Ho:YAG 2.1 µm surgical lasers for lithotripsy and prostate ablation
- Burnable poison rods in some pressurized water reactor cores
- Yellow-pink colorant for cubic zirconia and specialty optical glass