Palladium

If you discovered a new element, what would you do? Wouldn't you want to tell people about it right away? Not British chemist William Hyde Wollaston...

In 1802, Wollaston was primarily focused on figuring out how to process large amounts of platinum ore. During his research, Wollaston inadvertently discovered a new element—palladium—in some platinum ores from South America. Wollaston named the element after the recently discovered asteroid—Pallas, which in turn had been named after Pallas Athena, the Greek goddess of wisdom, warfare, and handicraft.

Announcing his discovery would have revealed his methods for purification and compromised his business that relied on that process to purify platinum. Instead of claiming the discovery, Wollaston anonymously sold some samples of palladium, teasingly advertising the metal as “new silver” and tempting other scientists to identify it—perhaps in an attempt to solicit peer review.

Irish chemist Richard Chenevix wrongly concluded that the metal was an alloy of platinum and mercury. Despite being wrong, Chenevix was awarded the Royal Society's most prestigious award, the Copley Medal, for his work. Knowing the award was undeserved, Wollaston anonymously offered a reward to anyone who could reproduce Chenevix's experimental claims.

Ultimately, Wollaston revealed himself and announced his discovery of palladium in 1805, disclosing his process for isolation and proving that the substance was in fact its own element.

Palladium is a shiny and silvery white metal that looks a lot like platinum. It’s not terribly toxic, as far as metals go. Relative to the other platinum group metals, it has a low melting point, and it isn’t very dense. Because palladium doesn’t interact with oxygen at room temperature, it won’t tarnish.

Most palladium is used in catalytic converters—the part of a car’s exhaust system that turns harmful emissions, like carbon monoxide, into less harmful ones, like carbon dioxide. Palladium helps clean the air we breathe!

That’s not all palladium is used for, though. Palladium can absorb up to 900 times its weight in hydrogen gas, which makes it useful in separating and purifying hydrogen. Increasingly, palladium and other platinum group metals are being used in fuel cells, which can turn hydrogen into electricity.

Other uses for palladium include ceramic capacitors, which are used in laptop computers and smartphones. If you’ve ever seen someone sporting a piece of white gold jewelry, you’ve probably seen palladium: white gold is often produced by alloying gold with palladium.

In nature, you’ll find palladium in seven isotopes. Six of these are stable (non-radioactive): palladium-102, palladium-104, palladium-105, palladium-106, palladium-108, and palladium-110. Palladium-106 is the most common isotope, with around 27% of palladium occurring in this form. Palladium-108 gets second place at around 26.5% of naturally occurring palladium.

Palladium-107 is unstable (radioactive) but it still has a very long half-life (around 6.5 million years) compared to other radioactive elements. Scientists have created many radioactive palladium isotopes, with half-lives ranging from 21 hours to less than a second.

Most palladium comes from South African ores, although Russia and Zimbabwe are also major palladium producers. Palladium ores often contain other platinum group metal elements, such as platinum, rhodium, and ruthenium. Because palladium is often used in automobiles’ catalytic converters, which can be recycled, recycling is also a major source.