Element Samarium, Sm, Lanthanide

Samarium is one of the less common of the rare earth elements, being on the one hand much less abundant than the other elements of the cerium group, and on the other hand much more abundant than europium, terbium, and thulium. It is about as plentiful as gadolinium.

Another method for the separation of samarium from lanthanum, praseodymium, and neodymium may conveniently be mentioned here; its theoretical value has been pointed out by Matignon and Cazes, but its practical value does not appear to have, been determined. The mixed oxides are converted into the mixed anhydrous chlorides by the method of Bourion or some other suitable process, and heated to redness in a stream of dry hydrogen. The samarium is thus converted into the lower chloride SmCl₂, which may be isolated from the mixture by extracting the other chlorides with alcohol. If, on the other hand, the mixed chlorides are dissolved in a large quantity of water, about one-third of the samarium separates as hydroxide and the washed precipitate may be freed from small quantities of oxychlorides by dissolving it in cold, dilute hydrochloric acid, in which the oxychlorides are insoluble.

Samarium is a yellow metal of density 7.7-7.8. It is as hard as steel and melts at 1300°-1400°. The metal quickly tarnishes in the air.

Samarium had been discovered as a result of persistent chemical-analytical and spectral research of didimia earth, extracted by Mosander from ceria earth. Several decades after Mosander's isolation of didimia earth form lanthana an element didymium was supposed to exist, however some chemists suspected that it was, in fact, a mixture of several elements. In 19^th century the didimia earth was separated from the mineral samarskite that was first found in the in the Il'menskeye mountains, by the late 1870s, and it was from that source that the samarium-bearing didymium had originated.

The samarskite mineral was named after Vasili Samarsky-Bykhovets, the Chief of Staff (Colonel) of the Russian Corps of Mining Engineers in 1845-1861.

In 1878 Delafontaine reports about two blue spectrum lines; he supposed that they belonged to another new metal found in samarskite, this time he gave this element the name decipium, after the Latin "decipiens", which means "deceptive, misleading". According to Delafontaine, samarskite contains the earths yttria, erbia, terbia, philippia, decipia, thoria, didymia, and ceria.

This issue was solved in 1879, when Francois Lecoq de Boisbaudran analyzed samarskite and noted that another earth precipitated before didymia when ammonium hydroxide was added. Spectral analysis showed two new blue lines, different from the lines of decipium. Lecoq called the new earth Samaria after its mineral source. The name for the element within became samarium.

Lanthanide Samarium crustal abundance is 7x10^-4 mass %, in seawater 2.3x10^-6 mg/L. Along with other rare earth elements it is contained in monazite, bastnasite (0.7-1.3% of Sm₂O₃), loparite, and samarskite as well as in gadolinite, orthite etc.

Biological role is not clear, however it is known that samarium stimulates metabolism. It is slightly toxic, as other rare earth elements.