Ytterbium

Like other rare-earth elements, discovering ytterbium was a long process!

Ytterbium’s story goes back to 1789, when Swedish chemist Johan Gadolin discovered the element yttrium (not to be confused with ytterbium) in an ore sample from the town of Ytterby, Sweden. It turned out, though, that the sample of yttrium oxide that Gadolin had extracted wasn’t pure. In 1843, Swedish chemist Carl Gustaf Mosander found the new elements terbium and erbium in yttrium oxide as well. But these elements weren’t in their pure form, either.

It wasn’t until 1878 that Swiss chemist Jean Charles Galissard de Marignac found ytterbium, a new element, in a sample of erbium. The rare-earth elements are so similar that it was hard to separate out the ytterbium, but after a lot of hard work, de Marignac succeeded. Sometimes, persistence pays off!

As it happens, at around the same time that de Marignac found ytterbium, so too did Austrian chemist Carl Auer von Welsbach. Von Welsbach named the new element aldebaranium, but it was de Marignac who wound up getting credit for finding the element, and de Marignac’s name for the element—ytterbium, after the Swedish town—is the one that stuck.

Incidentally, in 1907, French chemist Georges Urbain succeeded in splitting the ytterbium that de Marignac had discovered into two elements: ytterbium and a new element that he called lutetium.

Ytterbium is a soft, silvery-white metal that, like other rare-earth elements, is malleable (meaning it can be hammered into shape) and ductile (meaning it can be stretched without breaking). Ytterbium is more reactive than some rare-earth elements, which is why it will tarnish in air.

Some metals are hard to work with, but ytterbium is fairly cooperative. But powdered ytterbium does pose a fire risk—see below!

Ytterbium doesn’t have all that many uses. It has been mixed into stainless steel alloys to make the metal stronger. It has also been used as a radiation source in commercial X-ray machines, and it’s been used in bubble memory devices (a type of computer memory), too.

In other contexts, ytterbium is used as a catalyst, helping to make certain chemical reactions occur. Ytterbium has been incorporated into certain kinds of laser devices as well.

Like other rare-earth elements, most ytterbium compounds form in the +3-oxidation state. Unlike other rare-earth elements, ytterbium also forms compounds in its +2 state. Those oxidation states indicate how many electrons the element has lost during a chemical reaction.

Ytterbium oxide is the only widely used ytterbium compound, and it’s sometimes used in glass and ceramics.

In nature, you’ll find ytterbium in seven stable (non-radioactive) isotopes: ytterbium-168, ytterbium-170, ytterbium-171, ytterbium-172, ytterbium-173, ytterbium-174, and ytterbium-176. Most naturally occurring ytterbium is ytterbium-174: about a third of natural ytterbium is this isotope.

Scientists have also observed some 27 radioactive ytterbium isotopes. The most stable of these, ytterbium-169, has a half-life of around 32 days, while the shortest-lived have half-lives of much less than a second.

Most ytterbium comes from monazite ores. Like other rare-earth elements, it’s also found in the mineral bastnäsite, although ytterbium occurs in bastnäsite in small enough quantities that it’s not commonly extracted from this mineral. Some rare-earth elements are indeed rare, but not ytterbium—it’s the 44th most abundant element in the Earth’s crust!

China is the top producer of bastnäsite ores, so it’s the top producer of ytterbium, too. Russia and Malaysia also produce ytterbium.