7440-60-0
| Name | HOLMIUM |
| CAS | 7440-60-0 |
| EINECS(EC#) | 231-169-0 |
| Molecular Formula | Ho |
| MDL Number | MFCD00011049 |
| Molecular Weight | 164.93 |
| MOL File | 7440-60-0.mol |
Chemical Properties
| Definition | Metallic element of atomic number 67, group IIIB of the periodic table, one of the rare-earth elements of the yttrium subgroup, aw 164.9303, valence of 3, no stable isotopes. |
| Appearance | grey metal ingot |
| Melting point | 1474 °C |
| Boiling point | 2695 °C |
| density | 8.8 g/mL at 25 °C(lit.) |
| solubility | soluble in dilute acid solutions |
| form | ingot |
| color | Silver-gray |
| Specific Gravity | 8.795 |
| Water Solubility | reacts slowly with H2O, soluble dilute acids [HAW93] |
| Sensitive | Air & Moisture Sensitive |
| Merck | 13,4747 |
| Exposure limits | ACGIH: TWA 2 ppm; STEL 4 ppm OSHA: TWA 2 ppm(5 mg/m3) NIOSH: IDLH 25 ppm; TWA 2 ppm(5 mg/m3); STEL 4 ppm(10 mg/m3) |
| History | The spectral absorption bands of holmium were noticed in 1878 by the Swiss chemists Delafontaine and Soret, who announced the existence of an “Element X.” Cleve, of Sweden, later independently discovered the element while working on erbia earth. Holmium is named after Cleve’s native city. Pure holmia, the yellow oxide, was prepared by Homberg in 1911. Holmium occurs in gadolinite, monazite, and in other rare-earth minerals. It is commercially obtained from monazite, occurring in that mineral to the extent of about 0.05%. It has been isolated by the reduction of its anhydrous chloride or fluoride with calcium metal. Pure holmium has a metallicto bright silver luster. It is relatively soft and malleable, and is stable in dry air at room temperature, but rapidly oxidizes in moist air and at elevated temperatures. Holmium has unusual magnetic properties. Few uses have yet been found for the element. The element, as with other rare earths, seems to have a low acute toxic rating. Natural holmium consists of one isotope 165Ho, which is not radioactive. Holmium has 49 other isotopes known, all of which are radioactive. The price of 99.9% holmium metal is about $20/g. |
| Uses | |
| CAS DataBase Reference | 7440-60-0(CAS DataBase Reference) |
| EPA Substance Registry System | Holmium (7440-60-0) |