Scandium

Scandium’s discovery was predicted years in advance, when Russian chemist Dmitri Mendeleev published his groundbreaking periodic table—the one on which the modern periodic table is based! In 1869, Mendeleev's table predicted the existence of 10 as-yet-unknown elements. Mendeleev predicted one of these elements would have an atomic weight between 40 (calcium) and 48 (titanium). He called it “ekaboron” (meaning “like boron”) and it turned out to be the transition metal scandium.

Swedish chemist Lars Fredrik Nilson separated the oxide of scandium from a mineral called euxenite in 1879, a decade after Mendeleev’s prediction. Nilson named element 21 after the Latin word for Scandinavia. Scandium has qualities that closely matched what Mendeleev predicted for the element, thereby validating the periodic table’s predictive powers. This is still important for research today and helps guide discoveries. No crystal ball required!

Scandium is a soft, relatively light, silvery metal that, when exposed to air, takes on a yellow or pinkish tint. Scandium’s qualities are more like those of yttrium, which shares the same column, than to those of titanium, which shares the same row.

Scandium is often alloyed with aluminum because scandium-aluminum alloys are stronger than aluminum alone. These alloys also have a higher melting point, which allows them to be welded. The alloys are used in everything from aerospace components (early applications included in Soviet missiles MiG fighter planes) to sporting equipment (such as baseball bats and bicycle frames). If anyone asks you what a Soviet fighter plane and a baseball bat have in common, the answer is scandium! Scandium is also added to mercury vapor lamps to help make light that looks like sunlight.

In water, scandium precipitates as scandium hydroxide (Sc(OH)₃), which is why it’s so widely dispersed throughout the Earth’s crust. Scandium oxide (Sc₂O₃), also known as scandia, is the form of scandium that’s the most commercially available and serves as the starting point for scandium metal.

Naturally occurring scandium only exists as the isotope scandium-45. Scientists have documented 25 radioactive isotopes of scandium. The longest-lived isotope, scandium-46, has a half-life of around 84 days; the shortest-lived has a half-life of only nanoseconds. A nanosecond is one billionth of a second!

Scandium isn’t especially rare—it’s the 35th most abundant element in the Earth’s crust—but because it’s widely dispersed in small amounts, it is expensive to produce. Most of the world’s scandium supply comes from mines in China, Russia, and Malaysia, where it is extracted as a byproduct of uranium processing.