Palladium
Palladium is a lustrous, silvery-white metal from the platinum group, prized both for its catalytic properties and for its unusual ability to soak up huge volumes of hydrogen gas. It's named after Pallas, an asteroid discovered just before the element itself.
- Group · Period
- 10 · 5
- At room temp
- solid
- Melts at
- 1828.05 K
- Density
- 12 g/cm³
- Discovered
- 1803
Uses
Palladium’s largest single use is inside catalytic converters, where it helps convert harmful pollutants in vehicle exhaust into less harmful gases, a role that consumes the majority of the palladium produced each year. In electronics, palladium is used in multilayer ceramic capacitors and various connectors and contacts, valued for its conductivity and resistance to corrosion. It’s also alloyed into white gold jewelry and used in some dental alloys and restorations.
Separately, palladium’s remarkable capacity to absorb hydrogen gas — far more than its own volume — has made it a valuable material in research on hydrogen purification and storage, since hydrogen gas passed through palladium can be filtered to a very high purity.
History
Palladium was discovered in 1803 by English chemist William Hyde Wollaston, who isolated it while working through the complex residues left over from dissolving crude platinum ore in acid — the same broader investigation that also led him to rhodium. Wollaston initially introduced palladium to the scientific community somewhat unusually, by selling samples of it anonymously through a shop before formally revealing himself as the discoverer. He named the new element after Pallas, an asteroid that had been discovered only shortly before, continuing a period tradition of linking new chemical discoveries to recent astronomical ones.
Fun facts
- Palladium can absorb up to roughly 900 times its own volume of hydrogen gas, a property researchers have explored for hydrogen storage and purification.
- It's named after the asteroid Pallas, which had been discovered only a year or two before the element itself.
- Like rhodium, the majority of the world's palladium is used inside catalytic converters to help clean up vehicle exhaust emissions.
Frequently asked questions
How much hydrogen can palladium really absorb?
An extraordinary amount for a solid metal — palladium can soak up several hundred times its own volume of hydrogen gas, with figures cited as high as around 900 times. The hydrogen atoms slot into the spaces between the metal's own atoms, which is why palladium has long interested researchers working on hydrogen storage and purification.
Why is palladium named after an asteroid?
William Hyde Wollaston discovered palladium in 1803, shortly after the asteroid Pallas had been discovered and was generating excitement in the scientific world. Naming new discoveries after recent astronomical finds was a fairly common practice at the time, and Wollaston followed suit.
What's the connection between palladium and platinum?
They're both platinum-group metals that typically occur together in the same ore deposits and share a family resemblance in their chemistry, including strong catalytic properties. Palladium is generally lighter and less dense than platinum, and the two are often used for overlapping industrial and jewelry applications.
Compounds
5 notable compounds containing Pd
- Pd(OAc)2reagent
Palladium(II) acetate
An orange-brown, soluble palladium salt that is one of the most widely used catalysts in modern organic chemistry, central to many carbon-carbon bond-forming reactions.
Used for: Catalyst for Heck, Suzuki, and other palladium-catalyzed cross-coupling reactions
- PdCl2salt
Palladium(II) chloride
A brownish-red salt and the most important commercial palladium compound, serving as the entry point for the vast majority of palladium catalysts used in industry.
Used for: Precursor for palladium cross-coupling catalysts and carbon monoxide detectors
- Pd(NO3)2salt
Palladium(II) nitrate
A water-soluble palladium salt commonly supplied as a dilute solution, used as a convenient soluble palladium source for catalyst preparation and plating.
Used for: Soluble palladium source for catalyst impregnation and plating solutions
- PdOoxide
Palladium(II) oxide
A black solid formed when palladium metal is heated in oxygen, used as a catalyst and as an intermediate in recovering palladium from spent catalytic materials.
Used for: Catalyst in oxidation reactions and hydrogenation catalyst precursor
- [Pd(NH3)4]Cl2salt
Tetraamminepalladium(II) chloride
A water-soluble coordination compound in which four ammonia molecules surround a central palladium ion, used as a convenient palladium source for plating baths.
Used for: Palladium source in electroless and electrolytic plating solutions
Isotopes
42 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Pd-102 stable | 1.02% | Stable | — | -87,902.96 keV | 8,580.29 keV | — |
| Pd-104 stable | 11.14% | Stable | — | -89,395.12 keV | 8,584.85 keV | — |
| Pd-105 stable | 22.33% | Stable | — | -88,417.91 keV | 8,570.65 keV | — |
| Pd-106 stable | 27.33% | Stable | — | -89,907.54 keV | 8,579.99 keV | — |
| Pd-108 stable | 26.46% | Stable | — | -89,524.22 keV | 8,567.02 keV | — |
| Pd-110 stable | 11.72% | Stable | — | -88,330.9 keV | 8,547.16 keV | — |
Show all 42 isotopes
| Pd-90 | — | — | Electron capture / beta-plus decay (100%), Two-proton emission, ECP | -39,710 keV | 8,113 keV | — |
| Pd-91 | — | — | Electron capture / beta-plus decay (100%) | -46,170 keV | 8,183 keV | — |
| Pd-92 | — | 1.0 s | Electron capture / beta-plus decay (100%) | -54,779.1 keV | 8,275.57 keV | 4.56 × 10-16 eV |
| Pd-93 | — | 1.00 s | Electron capture / beta-plus decay (100%), ECP | -58,981.81 keV | 8,318.56 keV | 4.56 × 10-16 eV |
| Pd-94 | — | 9.0 s | Electron capture / beta-plus decay (100%) | -66,102.28 keV | 8,391.68 keV | 5.07 × 10-17 eV |
| Pd-95 | — | 5 s | Electron capture / beta-plus decay (100%) | -69,965.91 keV | 8,428.98 keV | 9.12 × 10-17 eV |
| Pd-96 | — | 122 s | Electron capture / beta-plus decay (100%) | -76,183.42 keV | 8,490.02 keV | 3.74 × 10-18 eV |
| Pd-97 | — | 3.10 m | Electron capture / beta-plus decay (100%) | -77,805.85 keV | 8,502.43 keV | 2.45 × 10-18 eV |
| Pd-98 | — | 17.7 m | Electron capture / beta-plus decay (100%) | -81,320.99 keV | 8,533.9 keV | 4.30 × 10-19 eV |
| Pd-99 | — | 21.4 m | Electron capture / beta-plus decay (100%) | -82,182.86 keV | 8,537.93 keV | 3.55 × 10-19 eV |
| Pd-100 | — | 3.63 d | Electron capture (100%) | -85,212.67 keV | 8,563.57 keV | 1.45 × 10-21 eV |
| Pd-101 | — | 8.47 h | Electron capture / beta-plus decay (100%) | -85,432.15 keV | 8,560.86 keV | 1.50 × 10-20 eV |
| Pd-103 | — | 16.991 d | Electron capture (100%) | -87,456.98 keV | 8,571.02 keV | 3.11 × 10-22 eV |
| Pd-107 | — | 6.5E+6 Y | Beta-minus decay (100%) | -88,372.65 keV | 8,560.89 keV | 2.22 × 10-30 eV |
| Pd-109 | — | 13.59 h | Beta-minus decay (100%) | -87,606.48 keV | 8,544.88 keV | 9.33 × 10-21 eV |
| Pd-111 | — | 23.4 m | Beta-minus decay (100%) | -85,985.89 keV | 8,521.75 keV | 3.25 × 10-19 eV |
| Pd-112 | — | 21.04 h | Beta-minus decay (100%) | -86,321.04 keV | 8,520.72 keV | 6.02 × 10-21 eV |
| Pd-113 | — | 93 s | Beta-minus decay (100%) | -83,590.5 keV | 8,492.58 keV | 4.91 × 10-18 eV |
| Pd-114 | — | 2.42 m | Beta-minus decay (100%) | -83,490.35 keV | 8,488.01 keV | 3.14 × 10-18 eV |
| Pd-115 | — | 25 s | Beta-minus decay (100%) | -80,425.82 keV | 8,457.73 keV | 1.82 × 10-17 eV |
| Pd-116 | — | 11.8 s | Beta-minus decay (100%) | -79,831.03 keV | 8,449.28 keV | 3.87 × 10-17 eV |
| Pd-117 | — | 4.3 s | Beta-minus decay (100%) | -76,423.89 keV | 8,416.92 keV | 1.06 × 10-16 eV |
| Pd-118 | — | 1.9 s | Beta-minus decay (100%) | -75,388.36 keV | 8,405.22 keV | 2.40 × 10-16 eV |
| Pd-119 | — | 0.92 s | Beta-minus decay (100%) | -71,407.28 keV | 8,368.96 keV | 4.96 × 10-16 eV |
| Pd-120 | — | 492 ms | Beta-minus decay (100%), Beta-minus, neutron emission (0.7%) | -70,279.6 keV | 8,357.08 keV | 9.27 × 10-16 eV |
| Pd-121 | — | 285 ms | Beta-minus decay (100%), Beta-minus, neutron emission (0.8%) | -66,182.34 keV | 8,320.86 keV | 1.60 × 10-15 eV |
| Pd-122 | — | 175 ms | Beta-minus decay (100%), Beta-minus, neutron emission (2.5%) | -64,616.17 keV | 8,305.98 keV | 2.61 × 10-15 eV |
| Pd-123 | — | 109 ms | Beta-minus decay (100%), Beta-minus, neutron emission (1.4%) | -60,429.75 keV | 8,270.03 keV | 4.19 × 10-15 eV |
| Pd-124 | — | 38 ms | Beta-minus decay (100%), Beta-minus, neutron emission | -58,400 keV | 8,252 keV | 1.20 × 10-14 eV |
| Pd-125 | — | 57 ms | Beta-minus decay (100%), Beta-minus, neutron emission | -53,960 keV | 8,215 keV | 8.00 × 10-15 eV |
| Pd-126 | — | 48.5 ms | Beta-minus decay (100%), Beta-minus, neutron emission (4.9%) | -51,790 keV | 8,197 keV | 9.41 × 10-15 eV |
| Pd-127 | — | 38 ms | Beta-minus decay (100%), B-2N, Beta-minus, neutron emission | -47,220 keV | 8,160 keV | 1.20 × 10-14 eV |
| Pd-128 | — | 35 ms | Beta-minus decay (100%), Beta-minus, neutron emission | -44,390 keV | 8,137 keV | 1.30 × 10-14 eV |
| Pd-129 | — | 31 ms | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -37,880 keV | 8,086 keV | 1.47 × 10-14 eV |
| Pd-130 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -32,730 keV | 8,046 keV | — |
| Pd-131 | — | — | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -25,740 keV | 7,993 keV | — |