| Symbol | Ho |
| Atomic number | 67 |
| Group | - |
| Period | 6 |
| Block | f |
| Classification | Lanthanide |
| Appearance | Silvery white |
| Color | Silver |
| Number of protons | 67 p+ |
| Number of neutrons | 98 n0 |
| Number of electrons | 67 e- |
| Phase at STP | Solid |
| Density | 8.79 g/cm3 |
| Atomic weight | 164.93 u |
| Melting point | 1734 K 1460.85 °C 2661.53 °F |
| Boiling point | 2873 K 2599.85 °C 4711.73 °F |
| Heat of vaporization | 251.04 kJ/mol |
| Electronegativity (Pauling Scale) | 1.23 |
| Electron affinity | 32.61 kJ/mol |
| Oxidation states | 0, +1, +2, +3 (a basic oxide) |
| Ionization energies |
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| Discovery | Jacques-Louis Soret, Marc Delafontaine (1878) |
| First isolation | Per Teodor Cleve (1879) |
| Named by | Per Teodor Cleve (1879) |
Discovery of holmium Holmium was discovered through isolation by Swedish chemist Per Theodor Cleve and independently by Jacques-Louis Soret and Marc Delafontaine, who observed it spectroscopically in 1878. Its oxide was first isolated from rare-earth ores by Cleve in 1878. The element's name comes from Holmia, the Latin name for the city of Stockholm. As well, Per Teodor Cleve independently discovered the element while he was working on erbia earth (erbium oxide), and was the first to isolate it. Using the method developed by Carl Gustaf Mosander, Cleve first removed all of the known contaminants from erbia. The result of that effort was two new materials, one brown and one green. He named the brown substance holmia (after the Latin name for Cleve's home town, Stockholm) and the green one thulia. Holmia was later found to be the holmium oxide, and thulia was thulium oxide. Like many other lanthanides, holmium is found in the minerals monazite and gadolinite and is usually commercially extracted from monazite using ion-exchange techniques. | |