1879 Samarium

The book of science

Tom Sharp

ParisPaul-Émile Lecoq de Boisbaudran elements Samarium


Lecoq isolated impure samarium oxide from the radioactive mineral samarskite, which contains yttrium and cerium, uranium and iron, niobium, tantalum, titanium, and oxygen, named after Vassili Samarsky-Bykhovets, who had been a mining engineer in the Russian military. * Although Lecoq’s samarium oxide contained a bit of europium (found later), his spectral analysis showed two new blue lines that established it against a flurry of competing claims. * J. Lawrence Smith thought he had found a new element in samarskite, but it was a mix of terbium and holmium. Marc Delafontaine thought he had found another in samarskite but it was holmium. Delafontaine identified a second new element in samarskite, but it was later shown to be a mix of rare earths including samarium, neodymium, and praseodymium. Jean Charles Galissard de Marignac said he found two new elements in samarskite but one was samarium and the other . . . well, more on that later.

Atomic number 62

More common than tin just harder to isolate, samarium makes strong magnets when alloyed with cobalt. Samarium a minor component of mischmetal in lighter flints. Samarium(III) triflate an efficient Lewis acid catalyst. Samarium added to glass helps absorb infrared. Samarium-153 a radiation source kills cancer cells.

Doable stuff

The samarium-cobalt magnet was not developed until the early 1970s. Samarium is only slightly toxic, and part of an enzyme involved in DNA replication and repair. OK. The story of samarium seems to tell us that we may fumble. It may take us a long time; it may be difficult and uncertain, but an ideal is reachable.

It’s only a coincidence that Lecoq discovered both gallium and samarium, and that the atomic number of samarium is exactly twice the atomic number of gallium.

The history of the discovery of samarium shows us that this stuff isn’t easy. Rare earths are placed in the same locations in the periodic table because they are chemically very similar.

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