Palladium

Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare, shiny, silvery-white metal that was discovered in 1802 by an English scientist named William Hyde Wollaston. He named it after the asteroid Pallas, which was named for a title given to the Greek goddess Athena.

Palladium belongs to a group of metals called the platinum group, which includes platinum, rhodium, ruthenium, iridium, and osmium. Of these, palladium has the lowest melting point and is the least dense.

Palladium is very important because more than half of it is used in catalytic converters in cars. These devices help turn harmful gases from car exhaust, like hydrocarbons, carbon monoxide, and nitrogen dioxide, into safe substances such as nitrogen, carbon dioxide, and water vapor. Palladium is also used in electronics, dentistry, medicine, cleaning hydrogen, and even in jewelry.

Palladium isn't easy to find in nature. Big deposits are mainly found in places like the Bushveld Igneous Complex in South Africa, the Stillwater Complex in Montana, United States, the Sudbury Basin and Thunder Bay District in Ontario, Canada, and the Norilsk Complex in Russia. Because it is rare and useful, palladium is often bought and sold like other precious metals, sometimes in the form of palladium coins and bars.

Characteristics

Palladium is a soft, silver-white metal that looks like platinum. It is the least dense and has the lowest melting point of the platinum group metals. When heated, palladium can form a thin layer that gives it a slight brownish color.

Palladium does not react with oxygen at normal temperatures, so it does not tarnish in air. It can dissolve in certain acids, such as nitric acid, sulfuric acid, hydrochloric acid, and a special mix called aqua regia.

Isotopes

Main article: Isotopes of palladium

Naturally occurring palladium is made up of six stable types, called isotopes. Scientists have also found many other radioactive isotopes of palladium, which break down over time. Some of these change by capturing electrons and become rhodium, while others change by beta decay and become silver.

One special isotope, ¹⁰⁷Pd, was discovered in a meteorite and is also made when certain types of uranium break apart. It is considered one of the less harmful long-lasting products from such breakdowns.

Compounds

Palladium can form different compounds, mostly in two main states. These compounds are quite similar to those of platinum.

One important compound is made when palladium reacts with chlorine. This compound can be used to make other useful materials and helps in creating special chemical reactions. Palladium can also form other compounds when mixed with different substances, and these are important in making fine chemicals. Some of these compounds were recognized with a special prize in chemistry in 2010.

Occurrence

Palladium is found in mines around the world. In 2022, Russia produced the most, followed by South Africa, Canada, the U.S., and Zimbabwe.

It can be found mixed with other metals, like gold, in places such as the Ural Mountains, Australia, Ethiopia, and parts of North and South America. The main sources come from areas with lots of nickel and copper, like the Sudbury Basin in Ontario and the Norilsk–Talnakh area in Siberia. Other important places include the Merensky Reef in South Africa, and areas in Montana and Ontario.

Applications

Palladium is mainly used in special parts that help cars clean up harmful gases. It is also used to make beautiful jewellery, fix teeth, create precise timepieces, test blood sugar, build safe airplane parts, make important medical tools, and connect electric circuits. Some musical instruments, like special flutes, are made with palladium, too. Palladium can store and release hydrogen gas, which makes it useful in experiments and for checking carbon monoxide gas. It is also used in making strong metal mixtures and in creating very fine art prints that last a long time.

Catalysis

See also: Palladium-catalyzed coupling reactions

When broken into tiny pieces, palladium helps speed up important chemical reactions. It is used in making many useful products, like medicines and fuels, by helping join different parts of molecules together. Important discoveries about these reactions won a Nobel Prize in Chemistry in 2010.

Palladium helps create new kinds of materials for medicine and makes fuels cleaner.

Electronics

Palladium is used in tiny parts inside computers and other electronic devices. It helps make connections work better and lasts longer.

Technology

Palladium lets hydrogen gas pass through it easily when heated, which is useful for cleaning and studying hydrogen. It is also used in special tools to detect dangerous gases.

Hydrogen storage

Palladium can hold onto hydrogen gas very well, which scientists study for future ways to store clean fuel.

Medicine

Palladium is used in tiny amounts in tooth fillings and in the making of heart helpers that keep a steady beat.

Jewellery

Since 1939, palladium has been used to make shiny, white jewellery as a substitute for a more expensive metal. It can be shaped very thinly and keeps its beautiful look, though it can change color if heated too much.

Photography

Palladium is used in a special way to make long-lasting art prints that show details very clearly.

Effects on health

Palladium is a metal that does not often cause immediate harm to the body. However, recent studies show that over time and at the cellular level, especially in the liver and kidney, it can be more harmful. It seems to affect important parts of cells, leading to problems.

People usually absorb very little palladium when they eat or drink. Some plants can be harmed by small amounts of palladium, but most plants can handle it. Very high amounts of palladium might be dangerous and could possibly cause health issues, but there isn’t strong proof that it harms humans in everyday situations.

Like other metals in the platinum group, palladium in its normal form is not very reactive. Some people can have skin reactions from contact with it, especially if they are also sensitive to nickel. It’s best to avoid dental work with palladium for those who are allergic to nickel.

Small amounts of palladium can be released from car exhausts with catalytic converters and from certain dental work, but the amounts people usually get from these sources are very small. Workers who handle palladium or its compounds might be exposed to more. Soluble forms of palladium, like palladium chloride, are mostly removed from the body within a few days.

History

William Hyde Wollaston discovered a new metal in July 1802 and named it palladium in August of that year. He chose the name after the asteroid 2 Pallas, which had been found two months earlier and was once thought to be a planet. Wollaston shared his discovery in a shop in Soho in April 1803 without telling people who found it.

Palladium was found in platinum ore from South America. Wollaston used special steps to separate the metal from the ore. Later, palladium was once used to help treat a sickness, but better medicines were found. Today, most palladium is used in cars to help clean up exhaust fumes. Because it is valuable, some people steal these parts from cars. The price of palladium has changed a lot over the years because of supply and demand.

Palladium as investment

Palladium is used in many ways, including in cars, jewelry, and investments. Most of the world’s palladium comes from mines in South Africa, with Russia and mines in the United States and Canada also contributing a lot.

The price of palladium changed a lot over the years. It reached a very high price in 2021 because many cars needed it, but then the price dropped. Palladium can be bought and sold in markets around the world. Sometimes, extra palladium from old stockpiles in Russia affected the price.

Palladium producers

• Norilsk Nickel
• Sibanye-Stillwater
• Anglo American Platinum
• Impala Platinum
• Northam Platinum

Exchange-traded products

WisdomTree Physical Palladium (LSE: PHPD) is a special kind of investment tied to real palladium metal. It can be bought on many stock markets around the world. ETFS Physical Palladium Shares (NYSE: PALL) is another investment option available on the New York Stock Exchange.

Bullion coins and bars

People can also invest in palladium by buying special coins and bars made from it. Some popular palladium coins include the Canadian Palladium Maple Leaf, the Chinese Panda, and the American Palladium Eagle. However, there are fewer palladium coins available compared to more common precious metals like gold, platinum, and silver.