History and Production
From Greek dyspositos, meaning hard to get at. The elment was first discovered by P.-É Lecoq de Boisbaudran in 1886. The metal, however, was first isolated by G. Urbain in 1906. The metal can be extracted from
monazite, a mixture of rare earth phosphates and bastnaesite, a mixture of rare earth fluorocarbonates by means of solvent extraction and ion-exchange techniques, follow by reduction of its halides (chloride or fluoride) with calcium metal.
Its thermal neutron adsorption ability has potential uses in nuclear industry. It is used to make laser material together with vanadium and other rare earth metals.
It is also used as sources for infrared radiation for investigating chemical reactions.
The metal is silvery white luster in appearance. It is soft enough to be cut by a knife. It is ferromagnetic at -168°C and become superconductive at even lower temperature. Its natural abundance is 4.5 ppm,
often associates with other rare earths in minerals such as xenotime, gadolinite and euxenite.
Interatomic distance: 350.4 pm
Melting point: 1412°C
Boiling point: 2567°C
Thermal conductivity/Wm-1K-1: 10.7 (27°C)
Density/kgm-3: 8550 (20°C)
Standard Thermodynamic Data (atomic gas)
Enthalpy of formation: 290.4 kJ/mol
Gibbs free energy of formation: 254.4 kJ/mol
Entropy: 196.6 J/mol K
Heat capacity: 20.8 J/mol K
Electronic configuration: [Xe] 4f10 6s2
Term symbol: 5I8
Electron affinity: - Electronegativity (Pauline): 1.22
Ionization energy (first, second, third): 573.017, 1125.98, 2199.87 kJ/mol