Samarium, Sm, Atomic number 62

General

Samarium (after the mineral samarskite, which in turn named after the mining engineer W. M. Samarski) is a chemical element with atomic symbol Sm and atomic number 62. In the periodic table the element is silvery in the group of lanthanides and is thus also one of the rare earth metals.
The discovery of samarium exist in the literature, several representations.
1. 1853 showed the Swiss Jean Charles de Marignac Galissard samarium spectroscopy using a sharp absorption line in Didymoxid after. 1879 isolierte der Franzose Paul Emile Lecoq de Boisbaudran das aus dem Mineral Element Samarskit ((And,This,You,Faith)3(Nb,Take,You)5O16). Mineral- and item name are derived from the Russian mining inspector (Mining officials) Oberst Samarsky, who discovered the mineral.
2. 1878 The Swiss chemist discovered Marc Delafontaine samarium, which he calls Decipum, the didymium. 1879 independently discovered by Paul Emile Lecoq de Boisbaudran him samarium. 1881 shows Delafontaine, to be an isolated element contains another element samarium.
3. The under 1 mentioned spectroscopic detection of 1853 was Marignac 1878 Paul Emile Lecoq de von Boisbaudran gemacht.
1903 presented by the German chemist Wilhelm Muthmann metallic samarium ago by electrolysis.
Of course, does not occur elemental samarium. Some minerals such as monazite, Bastnaesite and samarskite however, contain the element. Monazite containing up to 1 % Samarium.

Extraction

Starting from monazite and bastnaesite, the separation of rare earths by ion exchange, Solvent extraction or electrochemical deposition. In a last step, the high purity samarium oxide with lanthanum metal reduced to the metal and sublimation.

Special features

In air, samarium is reasonably stable, it forms a passivating, oxide layer of yellowish. Shiny metallic samarium ignites above 150 ° C. It reacts with oxygen to Sm2O3 sesquioxide. It reacts violently with water to form hydrogen and Samariumhydroxid. The most stable oxidation state, as with all lanthanides +3. Samarium comes in three modifications. The transition points are located at 734 ° C and 922 ° C. Sm3 ions aqueous solutions of yellow color.
There are four stable and 19 unstable, radioaktive Isotope. The most frequent natural isotopes 152Sm (26,7 %), 154Sm (22,7 %) and 147Sm (15 %).

Use

Along with other rare earths for carbon arc lamps for Filmvorführanlagen.
Doping of calcium fluoride single crystals for lasers and masers.
Because of its large cross section for thermal neutrons and epithermal neutron absorbers as samarium is used in nuclear applications.
Samarium-Cobalt-Magnete :
Permanent magnets made of SmCo5 have a high resistance to demagnetization, and a coercive force of up to 2200 kA / m. The improved alloy is more expensive to manufacture Sm2Co17, but has higher magnetic properties and improved corrosion resistance.
They are used in step motors for quartz watches, Drive motors in micro tape recorders (Walkman, Dictation), Headphones, Sensors, Couplings in mixers and hard disk drives. As a weight-saving magnetic materials, they are also in the air- and space used.
Samarium oxide is added to optical glass to absorb infrared light.
Samarium is used to raise awareness of (Light-) Phosphorus when irradiated with infrared light.
As a catalyst; Samarium oxide catalyzes the hydrogenation and dehydrogenation of ethanol (Alcohol).
In medicine, the isotope 153Samarium in combination with a bisphosphonate (Lexidronam) used to treat bone cancer pain (Radionuclide therapy for bone metastases).
Compounds with samarium in the less favorable oxidation state +2 (especially samarium(II)-iodid und Samarium(II)-bromide) find application in organic synthesis (Reducing agent and one-electron Transferreagenz, of. B. samariumvermittelte pinacol couplings).
In conjunction with the radiopharmaceutical ethylenediaminetetra(methylenphosphonsäure) in nuclear medicine for palliative treatment of bone- and skeletal metastases.

General
Name, Symbol

Atomic number

Samarium, Sm, 62
Series Lanthanides
group, Period, Block The, 6, f
Appearance silvery white
CAS-Nummer 7440-19-9
Mass fraction of element 6 ppm
Atomic
Atomic mass 150,36 you
Atomradius 185 pm
Kovalenter Radius 198 pm
Elektronenkonf. [Car] 4f(6) 6s2
1. Ionization 544,5 KJ / mol
2. Ionization 1070 KJ / mol
3. Ionization 2260 KJ / mol
Physically
Physical State fixed
Crystal structure trigonal
Density 7,536 g/cm3 (25 ° C)
Magnetism paramagnetisch (χm = 1,12 * 10(-3))
Melting point 1345 K (1072 C)
Boiling point 2076 K (1803 C)
Molar Volume 19,98 * 10(-6)m(3)/mol
Heat of vaporization 175 KJ / mol
Schmelzwärme 8,6 KJ / mol
Electrical conductivity 1,06*10(6) A/(V * m)
Thermal conductivity 13 W /(m*K)
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