The chemical element holmium is classed as a lanthanide and rare earth metal. It was discovered in 1878 by Marc Delafontaine and Jacques-Louis Soret.
|Classification:||Holmium is a lanthanide and rare earth metal|
|Melting point:||1470 oC, 1743 K|
|Boiling point:||2700 oC, 2973 K|
|Neutrons in most abundant isotope:||98|
|Electron configuration:||[Xe] 4f11 6s2|
|Density @ 20oC:||8.80 g/cm3|
|Atomic volume:||18.7 cm3/mol|
|Structure:||hexagonal close packed|
|Specific heat capacity||0.16 J g-1 K-1|
|Heat of fusion||17.0 kJ mol-1|
|Heat of atomization||301 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|
|Minimum oxidation number||0|
|Min. common oxidation no.||0|
|Maximum oxidation number||3|
|Max. common oxidation no.||3|
|Electronegativity (Pauling Scale)||1.23|
|Polarizability volume||23.6 Å3|
|Reaction with air||vigorous, with heat ⇒ Ho2O3|
|Reaction with 15 M HNO3||mild, ⇒ H2, Ho(NO3)3|
|Reaction with 6 M HCl||mild, ⇒ H2, HoCl3|
|Reaction with 6 M NaOH||–|
|Atomic radius||175 pm|
|Ionic radius (1+ ion)||–|
|Ionic radius (2+ ion)||–|
|Ionic radius (3+ ion)||104.1 pm|
|Ionic radius (1- ion)||–|
|Ionic radius (2- ion)||–|
|Ionic radius (3- ion)||–|
|Thermal conductivity||16.2 W m-1 K-1|
|Electrical conductivity||1.1 x 106 S m-1|
|Freezing/Melting point:||1470 oC, 1743 K|
Discovery of Holmium
In 1878 Swiss 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. (1)
In 1879 Per Teodor Cleve in Sweden 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. (2), (2a)
Holmium oxide was isolated in 1886 by French chemist Paul Lecoq de Boisbaudran by fractional precipitation. (1a), (3)
The pure metal was isolated in 1911 by Otto Holmberg. (3)
The element name holmium comes from the Greek word ‘Holmia’ meaning Stockholm.
Appearance and Characteristics
Holmium is considered to be of low toxicity.
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.
When present in compounds, holmium exists usually in the trivalent state, Ho3+. Most holmium compounds are brownish yellow in color. (4)
Holmium has unusual magnetic properties, including the highest magnetic moment (10.6 µB) of any naturally occurring element.
Uses of Holmium
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.
Abundance and 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: $860 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 the metal is 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. Naturally occurring holmium consists of its one stable isotope, 165Ho.
1. Mary Elvira Weeks, The Discovery of the Elements XVI., Journal of Chemical Education., October 1932, p1761,1762.
1a. Mary Elvira Weeks, The Discovery of the Elements XVI., Journal of Chemical Education., October 1932, p1767.
2. Robert E. Krebs, The history and use of our earth’s chemical elements: a reference guide., JGreenwood Publishing Group, 2006, p296.
2a. Robert E. Krebs, The history and use of our earth’s chemical elements: a reference guide., JGreenwood Publishing Group, 2006, p300.
3. Andrew Ede, The chemical element: a historical perspective., Greenwood Publishing Group, 2006, p139.
4. Mary Eagleson, Concise encyclopedia chemistry., Walter de Gruyter, 1994, page 498.
5 Photo: Images of Elements
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