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Element Fact
Selenium is an essential trace element in the diets that acts as antioxidants.

Holmium, Ho

holmium sample

Atomic number: 67
Atomic mass: 163.93032(2)
Natural abundance: 1.4 ppm
Isotopes:
165Ho (163.93032) - 100%

History and Production

Named after Homia, Latin word for Stockholm. It was discovered by J.-L. Soret and M. Delafontaine by spectroscopic means. It was independently discovered by P.T. Cleve in 1879 who separated chemically from erbium and thulium. The element was subsequently named after Cleve's native city. It is now recovered mainly from monazite, a mixture of rare earth phosphates containing about 0.05% of the metal. Ion-exchange and solvent extraction techniques are used to isolate the salt and the metal is obtained by reduction of the fluoride (HoF3) with calcium. At present time, the use of the element is limited. It is used as a component for some electronic device and as a catalyst for ortho-para hydrogen conversion.

Physical Data

It is a bright silver metal, relatively soft and malleable. It is one of the most paramagnetic substance ever known. Holmium usually exists along with other rare earth metals in gadolinite and monazite and with a natural abundance of about 1.4 ppm of the earth's crust.

Interatomic distance: 348.6 pm
Melting point: 1474C
Boiling point: 2700C
Thermal conductivity/Wm-1K-1: 16.2 (27C)
Density/kgm-3: 8795 (20C)

Standard Thermodynamic Data (atomic gas)

Enthalpy of formation: 300.8 kJ/mol
Gibbs free energy of formation: 264.8 kJ/mol
Entropy: 195.6 J/mol K
Heat capacity: 20.8 J/mol K

Electronic data

Electronic configuration: [Xe] 4f11 6s2
Term symbol: 4I5/2
Electron affinity: -   Electronegativity (Pauline): 1.23
Ionization energy (first, second, third): 580.987, 1138.53, 2203.73 kJ/mol

Chemical properties


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