Scandium

Scandium (Sc) is a chemical element with atomic number 21. It is a silvery-white, lightweight metal that belongs to the group of elements known as transition metals. It is often classified among the rare earth elements because it occurs in the same mineral deposits as the lanthanides and shares similar chemical properties with yttrium.

The element is not found in concentrated deposits that can be easily extracted; instead, it is dispersed in small quantities across many ores. This makes it expensive and production limited when compared to iron or aluminium.

History of discovery

Scandium was predicted to exist in Dmitri Mendeleev's periodic table before it was actually found; Mendeleev called the then-unknown element "eka-boron". In the 19th century, it was later isolated from Scandinavian ores by Swedish scientists, and was named after Scandia, the Latin name for Scandinavia.

Physical and chemical properties

Sc is a lustrous metal with low density. When exposed to air, it develops a thin oxide coating on its surface that slows further corrosion. Its most common oxidation state is +3, forming compounds such as the oxide Sc₂O₃. It reacts with dilute acids, releasing hydrogen.

Applications

The principal use is in aluminium–scandium alloys (Al-Sc alloy), which provide strength and hardness while keeping the weight low. They are used in aircraft components, sporting equipment such as bicycles and baseball bats, and certain industrial applications. Scandium is also used in metal halide lamps that produce light close to sunlight, and in solid oxide fuel cells that use zirconia as the electrolyte.

Production

Scandium is generally obtained as a by-product in the processing of uranium, titanium, tungsten, or nickel-laterite ores. The global market for the element is small and prices fluctuate; this is one of the factors that limits widespread use of Al-Sc alloys.