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General
States Energies Oxidation & Electrons Appearance & Characteristics Reactions Compounds Radius Conductivity Abundance & Isotopes |
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General:
| Name: Holmium | Symbol: Ho |
| Type: Rare Earth, Lanthanide series | Atomic weight: 164.9304 |
| Density @ 293 K: 8.80 g/cm3 | Atomic volume: 18.7 cm3/mol |
| Discovered: In 1878 chemists Marc Delafontaine and Jacques-Louis Soret observed previously unrecorded spectroscopic lines. They announced the discovery of element 'X' - the element we now call holmium. In 1879 Per Teodor Cleve discovered two new materials - one brown and one green - while working with erbia (erbium oxide). The brown substance he named holmia, which he later found to be holmium oxide, and the green substance he named thulia, which is thulium oxide. The element name holmium comes from the Greek word 'Holmia', meaning Stockholm. | |
States
| State (s, l, g): solid | |
| Melting point: 1743 K (1470 oC) | Boiling point: 2973 K (2700 oC) |
Energies
| Specific heat capacity: 0.16 J g-1 K-1 | Heat of atomization: 301 kJ mol-1 |
| Heat of fusion: 17.0 kJ mol-1 | Heat of vaporization : 251.04 kJ mol-1 |
| 1st ionization energy: 580.7 kJ mol-1 | 2nd ionization energy: 1139 kJ mol-1 |
| 3rd ionization energy: 2204 kJ mol-1 | Electron affinity: kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,29,8,2 | Electron configuration: [Xe] 4f11 6s2 |
| Minimum oxidation number: 0 | Maximum oxidation number: 3 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 3 |
| Electronegativity (Pauling Scale): 1.23 | Polarizability volume: 23.6 Å3 |
Appearance & Characteristics
| Structure: hexagonal close packed | Color: silvery-white |
| Harmful effects: Holmium is considered to be of low toxicity. | Hardness: mohs |
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Characteristics:
Holmium is a bright, soft, silvery-white, rare earth metal that is both ductile and malleable. It does not react in dry air at normal temperatures, but rapidly oxidizes to a yellow oxide (Ho2O3) in moist air or when heated. It has unusual magnetic properties, including the highest magnetic moment (10.6 µB) of any naturally occurring element. |
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Uses:
As a result of its special magnetic properties, holmium is used in alloys for the production of magnets and as a flux concentrator for high magnetic fields. Holmia (holmium oxide) is used as a yellow or red coloring for glass and cubic zirconia. Holmium isotopes are good neutron absorbers and are used in nuclear reactor control rods. Holmium is also used in solid-state lasers for non-invasive medical procedures treating cancers and kidney stones. |
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Reactions
| Reaction with air: vigorous, with heat ⇒ Ho2O3 | Reaction with 6 M HCl: mild, ⇒ H2, HoCl3 |
| Reaction with 15 M HNO3: mild, ⇒ Ho(NO3)3 | Reaction with 6 M NaOH: |
Compounds
| Oxide(s): Ho2O3 (holmia) | Chloride(s): HoCl3 |
| Hydride(s): HoH2, HoH3 |
Radius
| Atomic radius: 175 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 104.1 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 16.2 W m-1 K-1 | Electrical conductivity: 1.1 x 106 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 1.2 parts per million by weight, 0.2 parts per million by moles | |
| Abundance solar system: per billion by weight, per trillion by moles | |
| Cost, pure: $1722 per 100g | |
| Cost, bulk: $ per 100g | |
| Source: Holmium is not found free in nature but is found in a number of minerals: mainly gadolinite and monazite. Commercially it is extracted by ion exchange from monazite sand and isolated by reducing its anhydrous fluoride with calcium metal. | |
| Isotopes: Holmium has 30 isotopes whose half-lives are known, with mass numbers 141 to 172. Of these, one is stable, 165Ho. | |
