Lutetium

Lutetium was the last of the lanthanide elements to be identified, but the time was ripe for its discovery. Most elements on the periodic table were discovered by one researcher at a time, and some elements were discovered by two researchers simultaneously. But lutetium has the distinction of having been discovered by three different scientists at once!

At the end of the 18th century, researchers began discovering the 15 elements that are now referred to as the lanthanide elements. This process was complicated by the fact that the lanthanide elements all have similar properties, and by the fact that at the time, nobody was sure how many lanthanides there were.

In 1794, yttrium was discovered, but the sample of yttrium oxide that researchers isolated turned out not to be pure yttrium. Over the next century, researchers would find that the supposed yttrium contained the elements ytterbium, erbium, terbium, holmium, thulium, and lutetium as well.

In 1907, French chemist Georges Urbain found lutetium in a sample of ytterbium oxide. He named the element lutecium after the Latin name for Paris, Lutetia (the element’s name was changed to lutetium in 1949). However, at the same time that Urbain discovered lutetium, so too did Austrian chemist Carl Auer von Welsbach and, separately, British chemist Charles James. A conflict ensued over who the element’s true discoverer was. In 1909, the International Commission on Atomic Weights, which was then the authority on naming the elements, gave credit for the discovery to Urbain.

Lutetium is a hard, silvery metal that resembles the other rare earth elements. As the last element in the lanthanide series, lutetium has the highest melting point and density of the lanthanides, and it is the hardest of these elements. In air, lutetium tarnishes slowly.

So far, researchers have found few uses for lutetium, partly because it is so expensive to produce. It has been used in oil refining and as an additive in gadolinium gallium garnet—a type of artificial crystal that has been used in magnetic-bubble memory devices (a type of computer memory). Researchers are exploring the possibility of using the radioactive isotope lutetium-177 to help diagnose and treat cancers. New uses for lutetium are being found all the time!

Lutetium reacts with the halogens to form lutetium(III) halides. In water, lutetium reacts to form lutetium hydroxide and hydrogen gas. Few lutetium compounds have attained widespread non-research use, although some of its compounds have been used in x-ray phosphors and optical lenses.

In nature, you’ll fine lutetium in two isotopes: lutetium-175 and lutetium-176. Lutetium-175 is stable ( non-radioactive). Lutetium-176 is radioactive, but the isotope has a very long half-life (of 3.78 x 10¹⁰ years). Researchers have produced 39 lutetium radioisotopes, and their half-lives range from over three years to much less than one second.

Lutetium is one of the rarest elements on Earth! It is found alongside other rare earth elements, especially yttrium, in certain ores (chiefly monazite). The biggest producer of lutetium, as of the other rare earth elements, is China, followed by Russia and Malaysia.