Element 57 in our International Year of the Periodic Table series is lanthanum. The first of the lanthanoid series of elements, lanthanum and its compounds find use in camera lenses, hybrid vehicles, and swimming pools.

The lanthanoid (or lanthanide) series of elements takes its name from lanthanum. These elements are so-called because of their chemical similarities (‘lanthanide’ means ‘like lanthanum’).

Lanthanum(III) oxide is used in some camera lenses. It’s added to reduce dispersion and improve the clarity of images. Canon’s premium lenses are designated ‘L lenses’, and discovering that lanthanum is used in some lenses got me wondering if there’s a fun chemistry link behind this. Sadly, it seems the L in this case just stands for ‘luxury’, and there’s nothing to suggest that these lenses use lanthanum(III) oxide.

Lanthanum metal is found alloyed with other metals in the anodes of hybrid car batteries. It can also be found in the motors of hybrid vehicles, where it helps increase the power and efficiency of the engine.

Finally, lanthanum chloride is sometimes added to swimming pools to prevent algal growth. It works by reacting with and removing phosphates from the pool water.

Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.

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