Thulium (Tm)
Thulium (Tm): The Medical X-Ray Element
Thulium is a soft, silvery metal from the lanthanide series (rare earth elements). It’s one of the rarer lanthanides, but it has a very special use—producing portable X-rays. Its name comes from Thule, an ancient name for Scandinavia, where it was first discovered.
Why Is Thulium Useful?
Even though it’s rare, thulium has some unique, high-tech applications:
Portable X-Rays: When exposed to a nuclear reactor, thulium can form the isotope thulium-170, which gives off gamma rays. Small “buttons” of this isotope are used in lightweight X-ray devices, making it possible to take medical X-rays in remote areas or battlefield conditions without large, heavy machines.
Lasers: Thulium is also used in surgical lasers that can cut and cauterize tissue with high precision, making operations safer and reducing healing time.
Biological Role & Natural Abundance
Thulium has no known biological role and is considered non-toxic.
It is never found in pure form in nature but occurs in tiny amounts in minerals like monazite. Extracting it requires complex chemical separation, such as ion exchange and solvent extraction. The pure metal can be obtained by reducing its fluoride with calcium or its oxide with lanthanum.
History of Discovery
1879 – Discovery: Swedish chemist Per Teodor Cleve discovered thulium while studying the mineral erbium, realizing it contained hidden new elements. He isolated the new element and named it after Scandinavia.
1911 – Purification: American chemist Theodore William Richards refined thulium to an ultra-pure state after an incredible 15,000 recrystallizations of thulium bromate! This allowed him to determine its atomic weight with great accuracy.