Palladium
Definition and meaning of Palladium in chemistry.
Palladium is a rare and lustrous silvery-white metal with the chemical symbol Pd and an atomic number of 46. It belongs to the platinum group metals and is widely recognized for its exceptional catalytic properties and strong resistance to corrosion. Discovered in 1803 by William Hyde Wollaston, it was named after the recently discovered asteroid Pallas.
In more detail
Located in group 10 of the periodic table, palladium shares many chemical and physical properties with platinum, rhodium, ruthenium, iridium, and osmium. It is a dense transition metal that possesses the unique ability to absorb up to 900 times its own volume of hydrogen gas at room temperature, forming palladium hydride. This exceptional characteristic makes it a crucial material in hydrogenation reactions, chemical synthesis, and emerging fuel cell technology. In nature, it occurs uncombined as a free metal and in natural alloys with other platinum group elements within placer deposits and magmatic sulfide ores. Palladium strongly resists oxidation at standard temperatures, maintaining its brilliance, high electrical conductivity, and structural integrity over time. When heated in ambient air to 800 degrees Celsius, it forms a surface layer of palladium(II) oxide (PdO), but it remarkably regains its luster at higher temperatures as the oxide spontaneously decomposes.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Pd |
| Atomic number | 46 |
| Atomic mass | 106.42 u |
| Category | Transition Metal |
| State at room temperature | Solid |
| Melting point | 1554.9 °C |
| Boiling point | 2963 °C |
| Year discovered | 1803 |
Palladium is primarily utilized in catalytic converters for automobile exhaust systems, where it actively helps convert toxic carbon monoxide and unburned hydrocarbons into less harmful carbon dioxide and water vapor.
Frequently asked questions
Can palladium absorb hydrogen?
Yes, palladium can absorb exceptionally large volumes of hydrogen gas at room temperature, forming a compound known as palladium hydride.
Is palladium reactive with common acids?
It dissolves slowly in hot concentrated nitric acid and sulfuric acid but does not react noticeably with most common acids at room temperature.