The Pricey Element Palladium

Introduction to Palladium

The element palladium is a shiny silvery-white metal. It closely resembles platinum and is used in catalytic converters, jewelry, and as a catalyst in experiments in the laboratory.

10 Fun Facts about Palladium

Before the element palladium was discovered, the name of the element was actually used as a term for magical items that provided someone protection (like the Trojan Palladium).
Roughly 40% of the world’s palladium comes from Russia and South Africa.
The “arc reactor” in Iron Man’s suit in the Marvel Cinematic Universe uses palladium, which is what slowly poisons him!
Palladium is so rare that all of the palladium ever mined, could fit into a typically-sized living room.
The iPhone has 0.015g of palladium in it.
Palladium is sometimes used in jewelry and is hypoallergenic.
The element takes its name after the asteroid Pallas, which comes from the Greek goddess of wisdom, Pallas.
Palladium can absorb hydrogen like a sponge; it absorbs up to 900 times its own volume.
Palladium is worth more than gold.
Palladium is the lightest and has the lowest melting point of the platinum group metals.

Palladium in the Periodic Table

Palldium has the atomic symbol Pd with an atomic number of 46. It is located in the d-block of the periodic table, between rhodium and silver. Palladium is the eighteenth element in the transition metals on the periodic table. Palladium has an electron configuration of $[Kr]5s^{2}4d^{8}$ . Additionally, the element has an electronegativity of 2.2 on the Pauling scale. Palladium also is one of the six elements (palladium, rhodium, ruthenium, osmium, iridium, and platinum) that belongs to the platinum group on the periodic table.

Palldium in Today’s World

Palladium as a Catalyst

The most common use for palladium is in catalytic converters. Before catalytic converters were used, a car’s internal combustion engine would burn the fuel and release toxins into the air such as hydrocarbons and nitrogen oxides that created a large amount of pollution. In 1973 scientists discovered a way to lessen this pollution excretion. They created a tube-like structure, most made of ceramics that is thinly coated with palladium. The exhaust from the burning of fuel travels through this and reacts with the nanoparticles of palladium, causing them to not be released into the air!

Since palladium acts as such a good sponge for hydrogen, chemists commonly use it as a catalyst of reactions that involve hydrogen and oxygen. These types of reactions are called organometallic reactions.

Palladium in Jewelry

Palladium is resistant to tarnishing as it doesn’t react with oxygen in the air. It also is more durable than gold with a 4.75 out of 10 on the Mohs Scale as compared to gold’s 2.5. After WWII and the restriction placed on platinum usage, these properties made the element palladium a valuable option in the world of jewelry making. It also, if crafted correctly, can appear more white than silver and white gold.

The element palladium is also used to create springs in watches as it doesn’t tear very much over time. However, the element is extremely rare and jewelry or objects made using palladium can be expensive.

Where is the Palladium Element Found?

The element palladium occurs in sulfur minerals such as braggite. It’s also found as a by-product of copper, zinc, nickel refining. It’s mined in places such as Brazil, Russia, South Africa, and Canada.

When and How was Palladium Discovered?

Palladium was discovered in 1803 by the English Chemist, William Hyde Wollaston. Wollaston was studying a platinum ore by dissolving in aqua regia (a concentrated solution of hydrochloric and nitric acids). After isolating the metal, the chemist put the metal up for sale with a mineral dealer in London. He posted handbills (little posters) that described the metal’s properties to see if anyone would buy it. Then Richard Chenevix, a celebrated chemist of the time declared the metal a platinum-mercury alloy. Wollaston then offered a reward to anyone who could recreate the metal, and nobody could. Then in 1805 in front of the Royal Society of London, Wollaston announced himself as the discoverer of palladium, saying he remained anonymous so as to discover more about the element.

Palladium in Chemistry – Compounds, Reactions, Isotopes, Oxidation States

Palladium Element Compounds and Reactions

Oxides: PdO, PdO₂
Halides: PdF₂, PdF₄, PdCl₂, PdI₂
Complexes: [Pd(C₂H₃O₂)₂]₃

One of the most important reactions involving the element palladium is that palladium-catalyzed cross-coupling. It sounds like it would be super complicated but it’s actually one of the most important reactions for organic syntheses! Cross-coupling becoemes most often used to create carbon-carbon bonds in the production of medicines such as naproxen, and anti-inflammatory. In 2010, Richard F. Heck and Akira Suzuki won the Noble Prize in Chemistry for developing a cross-coupling reaction that used palladium as a catalyst. Below is an example of a palladium-catalyzed cross-coupling reaction.

Isolation of Elemental Palladium

In 1803, after Wollaston dissolved the platinum ore as mentioned above, he performed a series of experiments on the palladium reside to get palladium cyanide. After getting this, Wollaston was able to heat the compound to leave just the element palladium behind. Today chemists still isolate palladium by using aqua regia to remove impurities. A yellow salt then precipitates, which becomes heated to leave elemental palladium.

Palladium Isotopes

Palladium has six stable isotopes: palladium-102, palladium-104, palladium-105, palladium-106, palladium-108, and palladium-110. It also has multiple radioactive isotopes but the most common and stable are palladium-107 with a half-life of 6.5 million years, palladium-103 with a half-life of 17 days, and palladium-100 with a half-life of less than 4 days.

Oxidation States of Palladium Element

Palladium can have one of four oxidation states: 0 (in its elemental form), +1, +2, and +4.

Properties of Palladium Element

Atomic Symbol: 46
Melting point: 1,555°C
Boiling point: 2,963°C
Density: 12.0 g/ml
Atomic weight: 106.42g
Atomic number: 46
Electronegativity: 2.2
Molar heat capacity: 25.98 J/(mol*K)
Classification: Transition metal
Natural abundance in the Earth’s crust: 0.0005 ppm
Electron shell configuration: $[Kr]5s^{2}4d^{8}$
Stable Isotopes: ¹⁰²Pd, ¹⁰⁴Pd, ¹⁰⁵Pd, ¹⁰⁶Pd, ¹⁰⁸Pd, ¹¹⁰Pd
Found naturally in braggite and in ores that have metals that are a part of the platinum metal group
Toxicity: non-toxic

Where Can I Buy the Palladium Element?

The element palladium is extremely rare and thus expensive. An ounce of the metal costs about 1,600 dollars. However, you can still buy it from limited buyers online in the form of coins or ore.