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Palladium

physical science Maturity 7-9 Next article →

Palladium is a rare and lustrous silvery-white metal. It is a chemical element with the symbol Pd and atomic number 46.

Wollaston William Hyde Jackson color
Wollaston William Hyde Jackson color

This metal belongs to a specific family called the platinum group metals. This group includes platinum, rhodium, ruthenium, iridium, and osmium. While these elements share similar chemical properties, palladium is unique. It has the lowest melting point and the lowest density of all the platinum group metals.

2005palladium (mined)
2005palladium (mined)

At the atomic level, palladium has a very unusual electron configuration. In the periodic table, it belongs to group 10. Most elements follow the Madelung rule for how electrons fill their shells. However, palladium's outermost electrons follow Hund's rule instead. It is more energetically favorable for palladium to have a completely filled 4d10 shell. This results in a 5s0 configuration, which is unique in period 5. This makes palladium the heaviest element with only one incomplete electron shell.

The most famous use of palladium is in catalytic converters. These devices are found in automobile exhausts to reduce pollution. More than half of the global supply of palladium is used for this purpose. In a catalytic converter, palladium acts as a catalyst to speed up chemical reactions.

Aufgeschnittener Metall Katalysator für ein Auto
Aufgeschnittener Metall Katalysator für ein Auto

It helps convert up to 90% of harmful gases into nontoxic substances. These harmful gases include hydrocarbons, carbon monoxide, and nitrogen dioxide. The palladium helps turn them into nitrogen, carbon dioxide, and water vapor.

Kumada Catalytic Cycle
Kumada Catalytic Cycle

Beyond cars, palladium is a versatile tool in organic chemistry. It is used in many "coupling reactions" to build complex molecules. These reactions are vital for the synthesis of fine chemicals. In 2010, the Nobel Prize in Chemistry was awarded to Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki for their work with palladium-catalyzed cross couplings.

Kumada Catalytic Cycle
Kumada Catalytic Cycle

Specific examples of these processes include the Heck reaction, the Suzuki coupling, and the Sonogashira coupling. Palladium compounds like palladium(II) acetate and tetrakis(triphenylphosphine)palladium(0) serve as important catalysts in these tasks.

Finding palladium is difficult because ore deposits are quite rare. Most commercial palladium comes from nickel-copper deposits. Some of the largest deposits are located in the Sudbury Basin in Ontario, Canada. Another major source is the Norilsk-Talnakh deposits in Siberia, Russia. The Bushveld Igneous Complex in South Africa also contains extensive deposits.

Platinum-palladium ore, Stillwater mine MT
Platinum-palladium ore, Stillwater mine MT

In the United States, the Stillwater Complex in Montana is a key source.

Sulfidic serpentintite (platinum-palladium ore) Johns-Manville Reef, Stillwater Complex
Sulfidic serpentintite (platinum-palladium ore) Johns-Manville Reef, Stillwater Complex

In 2022, total mine production reached 210,000 kilograms. Russia was the largest producer, contributing 88,000 kilograms. The company Norilsk Nickel alone accounts for 39% of the world's production.

Because of its limited supply and high utility, palladium is treated as a precious metal. It is often sold in the form of bars and coins.

RR3415-0002 25 rubles palladium 1989 Ivan III
RR3415-0002 25 rubles palladium 1989 Ivan III

It is one of only four metals with its own ISO currency codes, joining gold, silver, and platinum. Palladium also has many industrial applications in electronics and medicine. It is used in multi-layer ceramic capacitors as an electrode. It is also used in dentistry, jewelry, and even professional transverse flutes. It can even be found in blood sugar test strips and aircraft spark plugs.

Historically, the element was discovered in 1802 by the English chemist William Hyde Wollaston.

Wollaston William Hyde Jackson color
Wollaston William Hyde Jackson color

He named the metal after the asteroid 2 Pallas. This asteroid was named after a title for the Greek goddess Athena. This naming connects a modern industrial metal to ancient mythology. Today, palladium remains a vital part of global technology and chemistry. Its ability to facilitate complex reactions makes it indispensable to modern science.

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🖼️ Images & Media (10)
File:Pd(OAc)2.jpg
Pd(OAc)2.jpg
File:Platinum-palladium ore, Stillwater mine MT.JPG
Platinum-palladium ore, Stillwater mine MT.JPG
File:Sulfidic serpentintite (platinum-palladium ore) Johns-Manville Reef, Stillwater Complex.jpg
Sulfidic serpentintite...
File:2005palladium (mined).PNG
2005palladium (mined).PNG
File:Aufgeschnittener Metall Katalysator für ein Auto.jpg
Aufgeschnittener Metall Katalysator für...
File:RR3415-0002 25 rubles palladium 1989 Ivan III.jpg
RR3415-0002 25 rubles palladium 1989 Ivan III.jpg
File:Kumada Catalytic Cycle.png
Kumada Catalytic Cycle.png
File:Wollaston William Hyde Jackson color.jpg
Wollaston William Hyde Jackson color.jpg
File:Potw1749a Pallas crop.png
Potw1749a Pallas crop.png
Palladium Prices.webp
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