Holmium is a chemical element with the symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a relatively soft and malleable silvery-white metallic element, which is stable in dry air at room temperature. A rare earth metal, it is found in the minerals monazite and gadolinite.
A trivalent metallic rare earth element, holmium has the highest magnetic moment (10.6µB) of any naturally-occurring element and possesses other unusual magnetic properties. When combined with yttrium, it forms highly magnetic compounds.
Holmium is a relatively soft and malleable element that is fairly corrosion-resistant and stable in dry air at standard temperature and pressure. In moist air and at higher temperatures, however, it quickly oxidizes, forming a yellowish oxide. In pure form, holmium possesses a metallic, bright silvery luster. Holmium oxide has some fairly dramatic color changes depending on the lighting conditions. In daylight, it is a tannish yellow color. Under trichromatic light, it is a fiery orange red, almost indistinguishable from the way erbium oxide looks under this same lighting. This has to do with the sharp emission bands of the phosphors, and the absorption bands of both oxides.
| Technical Data | ||||||||
| Symbol | Ho | Density (25°C)/gcm3 : | 8.78 | |||||
| Atomic number | 67 | Melting point / °C | 1461 | |||||
| No. of naturally occurring isotopes | 1 | Boiling point / °C | -2600 | |||||
| Atomic weight | 164.9304 | ΔHfus/kJmol-1 | ||||||
| Outer electron configuration | 4f116s2 | ΔHvap/kJmol-1 | 280 | |||||
| Metal radius (6-coordinate)/pm | 176.2 | ΔHf(monoatomic gas)/kJmol-1 | 301 | |||||
| Ionic radius(6-coordinate)/pm III | 90.1 | ΔH (hydration Ln3+)/kJmol1 | 3667 | |||||
| Ionization energy/kJmol I | 574 | Electrical resistivity | ||||||
| Ionization energy/kJmol II | 1139 | (25°C)/jiohm cm | 94 | |||||
| Ionization energy/kJmol III | 2221 | Eo(M3+(aq)+ 3e- → M(s))/V | ||||||
| Evaporation Techniques | ||||||||
| Temperature (oC) >@ Vap. Pressure | Techniques | Remarks | ||||||
| 10-8 Torr | 10-6 Torr | 10-4 Torr | Electron Beam | Crucible | Coil | Boat | ||
| 650 Sublimes | 770 Sublimes | 950 Sublimes | Good | - | Tungsten | Tungsten & Tantalum | Go to Evaporation Sources Page | |