Discovery date : 1878
Discovered by: Per Teodor Cleve at Uppsala, Sweden
and independently by Marc Delafontaine and Louis Soret in Geneva, Switzerland
Origin of the name: The name is derived from the Latin name for Stockholm, 'Holmia'.
Allotropes :
~>HOLMIUM is a chemical element with symbol Ho and atomic number 67. Part of the lanthanide series, holmium is a rare-earth element. Holmium was discovered by Swedish chemist Per Theodor Cleve. Elemental holmium is a relatively soft and malleable silvery-white metal. It is too reactive to be found uncombined in nature, but when isolated, is relatively stable in dry air at room temperature. However, it reacts with water and corrodes readily and also burns in air when heated.
| FACT BOX | |||
| Group | Lanthanides | Melting point | 1472°C, 2682°F, 1745 K |
| Period | 6 | Boiling point | 2700°C, 4892°F, 2973 K |
| Block | f | Density (g cm−3) | 8.80 |
| Atomic number | 67 | Relative atomic mass | 164.930 |
| State at 20°C | Solid | Key isotopes | 165Ho |
| Electron configuration | [Xe] 4f116s2 | CAS number | 7440-60-0 |
| ChemSpider ID | 22424 | ChemSpider is a free chemical structure database | |
Holmium was discovered at Geneva in 1878 by Marc Delafontaine and Louis Soret, and independently by Per Teodor Cleve at Uppsala, Sweden. Both teams were investigating yttrium, which was contaminated with traces of other rare earths (aka lanthanoids) and had already yielded erbium which was later to yield ytterbium. Cleve looked more closely at what remained after the ytterbium had been removed, and realised it must contain yet other elements because he found that its atomic weight depended on its source. He separated holmium from erbium in 1878. Delafontaine and Soret also extracted it from the same source, having seen unexplained lines in the atomic spectrum. We cannot be certain that either group had produced a pure sample of the new element because yet another rare-earth, dysprosium, was to be extracted from holmium.