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About Palladium

Palladium Bohr

Palladium is one of six platinum-group metals, discovered by William Hyde Wollaston in 1802 as he attempted to process platina deposits into workable platinum metal. He named the new element after the also freshly discovered asteroid Pallas, and he initially made the strange decision to offer it for sale anonymously through distribution of an advertisement in 1803 but later disclosed his discovery officially in a scientific publication.

Palladium is similar to other platinum group elements in that it is a silvery metal that is relatively non-reactive, but of the group it has the lowest melting point and is the least dense. In its applications it is most similar to platinum: useful in metallic form for the production of a variety of products and as a catalyst. Palladium catalyzes reactions involved in petroleum cracking, water treatment, nitric acid production, and polymer manufacturing, and is found in catalytic converters and fuel cells as a catalyst. Additionally, palladium is used to increase the rate of hydrogenation and dehydrogenation reactions, and serves many specialized catalytic functions in organic chemistry. In fact, the 2010 Nobel Prize in Chemistry was given for the development of palladium-catalysed reactions used in organic synthesis. As a metal, palladium is used in in electronics for plating of components, electrical contacts, and solder, and is also found in jewelry, watches, blood sugar test strips, and surgical instruments. Alloyed with silver, palladium is used as electrodes in the production of multilayer ceramic capacitors. Finally, a niche use of both platinum and palladium salts is in the production of fine-art black and white photographic prints with the platinotype process.

Some other uses of palladium rely on chemistry unshared with platinum. Several of these involve useful interactions platinum has with hydrogen. As a gas, hydrogen easily diffuses through heated palladium, and thus palladium is used in the production of high purity hydrogen. Palladium also absorbs hydrogen gas, forming palladium hydride. This property is being researched for insights regarding hydrogen storage. Palladium chloride efficiently oxidizes carbon monoxide, and is used in detectors for the toxic but odorless gas. Additionally, radioactive palladium is under investigation for use in cancer treatment.

Like other platinum group metals, palladium is typically obtained for commercial use as a byproduct from nickel and copper mining and processing, but can also be obtained from ores rich in platinum and from alluvial deposits. Along with ruthenium and rhodium, palladium is a decomposition product of uranium and could theoretically be recovered from spent nuclear fuel, but the problems inherent in working with radioactive materials make this an impractical source for the rare element.

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Organometallics

Summary. Palladium is frequently alloyed with gold, silver, iridium and other platinum group elements for use in jewelry. The metal is used in surgical instruments and electrical contacts. Palladium is also an excellent hydrogenation and dehydrogenation catalyst and is available in many organometallic forms for this purpose. High Purity (99.999%) Palladium Oxide (PdO) PowderPalladium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. High Purity (99.999%) Palladium (Pd) Sputtering Target Palladium nanoparticles and nanopowders provide ultra-high surface area. Palladium oxide is available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Palladium fluoride is another insoluble palladium source for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Palladium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Palladium Properties

Palladium(Pd) atomic and molecular weight, atomic number and elemental symbolPalladium is a Block D, Group 10, Period 5 element. Palladium Bohr ModelThe number of electrons in each of palladium's shells is 2, 8, 18, 18 and its electron configuration is [Kr] 4d10. The palladium atom has a radius of 137.6.pm and its Van der Waals radius is 163.pm. In its elemental form, CAS 7440-05-3, palladium has a silvery white appearance. Elemental PalladiumPalladium is a member of the platinum group of metals (along with platinum, rhodium, ruthenium, iridium and osmium). Palladium has the lowest melting point and is the least dense of the group. Palladium can occurs as a natural alloy with other platinum-group metals. Nickel-copper deposits are the main commercial source of palladium. Palladium was first discovered by William Hyde Wollaston in 1802.

Symbol: Pd
Atomic Number: 46
Atomic Weight: 106.42
Element Category: transition metal
Group, Period, Block: 10, 5, d
Color: silvery white metallic/ silvery-white
Other Names: Palladio
Melting Point: 1554.9 °C, 2830.82 °F, 1828.05 K
Boiling Point: 2963 °C, 5365 °F, 3236 K
Density: 12.023 g·cm3
Liquid Density @ Melting Point: 10.38 g·cm3
Density @ 20°C: 12.02 g/cm3
Density of Solid: 12023 kg·m3
Specific Heat: 0.24 (kJ/kg K)
Superconductivity Temperature: N/A
Triple Point: 1825 K, 3.5 × 10 3 kPa
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 17.2
Heat of Vaporization (kJ·mol-1): 361.5
Heat of Atomization (kJ·mol-1): 377.4
Thermal Conductivity: 71.8 W·m?1·K?1
Thermal Expansion: (25 °C) 11.8 µm·m-1·K-1
Electrical Resistivity: (20 °C) 105.4 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 25.98 J·mol-1·K-1
Young's Modulus: 121 GPa
Shear Modulus: 44 GPa
Bulk Modulus: 180 GPa
Poisson Ratio: 0.39
Mohs Hardness: 4.75
Vickers Hardness: 461 MPa
Brinell Hardness: 310 MPa
Speed of Sound: (20 °C) 3070 m·s-1
Pauling Electronegativity: 2.2
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.35
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 1.8
Reflectivity (%): 72
Refractive Index: N/A
Electrons: 46
Protons: 46
Neutrons: 60
Electron Configuration: [Kr] 4d10
Atomic Radius: 137 pm
Atomic Radius,
non-bonded (Å):
2.1
Covalent Radius: 139±6 pm
Covalent Radius (Å): 1.3
Van der Waals Radius: 163 pm
Oxidation States: 0, +1, +2, +4, +6 (mildly basic oxide)
Phase: Solid
Crystal Structure: face-centered cubic
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 54.206
1st Ionization Energy: 520.23 kJ·mol-1
2nd Ionization Energy: 7298.22 kJ·mol-1
3rd Ionization Energy: 11815.13 kJ·mol-1
CAS Number: 5/3/7440
EC Number: 231-115-6
MDL Number: MFCD00011167
Beilstein Number: N/A
SMILES Identifier: [Pd]
InChI Identifier: InChI=1S/Pd
InChI Key: KDLHZDBZIXYQEI-UHFFFAOYSA-N
PubChem CID: 23938
ChemSpider ID: 22380
Earth - Total: 0.89 ppm
Mercury - Total: 1.79 ppm
Venus - Total: 0.87 ppm
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: 6.3
Earth -  Crust (Crustal Rocks), ppb by atoms: 1
Sun - Total, ppb by weight: 3
Sun - Total, ppb by atoms: 0.04
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 670
Meterorite (Carbonaceous), ppb by atoms: 130
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: William Hyde Wollaston
Discovery Date: 1803
First Isolation: William Hyde Wollaston (1803)

Health, Safety & Transportation Information for Palladium

Safety data for Palladium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) palladium.

Safety Data
Material Safety Data Sheet MSDS
Signal Word N/A
Hazard Statements N/A
Hazard Codes N/A
Risk Codes N/A
Safety Precautions N/A
RTECS Number N/A
Transport Information N/A
WGK Germany nwg
Globally Harmonized System of
Classification and Labelling (GHS)
N/A

Palladium Isotopes

Naturally occurring palladium (Pd) has four stable isotopes: 104Pd, 105Pd, 106Pd, and 108Pd.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
91Pd 90.94911(61)# 10# ms [>1.5 µs] β+to 91Rh 7/2+# N/A 731.06 -
92Pd 91.94042(54)# 1.1(3) s [0.7(+4-2) s] β+to 92Rh 0+ N/A 747.52 -
93Pd 92.93591(43)# 1.07(12) s β+to 93Rh (9/2+) N/A 760.26 -
94Pd 93.92877(43)# 9.0(5) s β+to 94Rh 0+ N/A 774.86 -
95Pd 94.92469(43)# 10# s β+to 95Rh 9/2+# N/A 786.67 -
96Pd 95.91816(16) 122(2) s β+to 96Rh 0+ N/A 800.33 -
97Pd 96.91648(32) 3.10(9) min β+to 97Rh 5/2+# N/A 810.28 -
98Pd 97.912721(23) 17.7(3) min β+to 98Rh 0+ N/A 822.08 -
99Pd 98.911768(16) 21.4(2) min β+to 99Rh (5/2)+ N/A 831.09 -
100Pd 99.908506(12) 3.63(9) d EC to 100Rh 0+ N/A 841.97 -
101Pd 100.908289(19) 8.47(6) h EC to 101Rh 5/2+ -0.66 857.5 -
102Pd 101.905609(3) Observationally Stable - 0+ N/A 865.58 1.02
103Pd 102.906087(3) 16.991(19) d EC to 103Rh 5/2+ N/A 873.66 -
104Pd 103.904036(4) STABLE - 0+ N/A 881.73 11.14
105Pd 104.905085(4) STABLE - 5/2+ -0.642 889.81 22.33
106Pd 105.903486(4) STABLE - 0+ N/A 897.89 27.33
107Pd 106.905133(4) 6.5(3)E+6 y β- to 107Ag 5/2+ N/A 905.97 -
108Pd 107.903892(4) STABLE - 0+ N/A 914.05 26.46
109Pd 108.905950(4) 13.7012(24) h β- to 109Ag 5/2+ N/A 922.13 -
110Pd 109.905153(12) Observationally Stable - 0+ N/A 930.21 11.72
111Pd 110.907671(12) 23.4(2) min β- to 111Ag 5/2+ N/A 938.28 -
112Pd 111.907314(19) 21.03(5) h β- to 113Ag 0+ N/A 946.36 -
113Pd 112.91015(4) 93(5) s β- to 114Ag (5/2+) N/A 945.13 -
114Pd 113.910363(25) 2.42(6) min β- to 115Ag 0+ N/A 953.2 -
115Pd 114.91368(7) 25(2) s β- to 116Ag (5/2+)# N/A 961.28 -
116Pd 115.91416(6) 11.8(4) s β- to 117Ag 0+ N/A 969.36 -
117Pd 116.91784(6) 4.3(3) s β- to 118Ag (5/2+) N/A 977.44 -
118Pd 117.91898(23) 1.9(1) s β- to 119Ag 0+ N/A 985.52 -
119Pd 118.92311(32)# 0.92(13) s β- to 120Ag N/A N/A 984.28 -
120Pd 119.92469(13) 0.5(1) s β- to 121Ag 0+ N/A 992.36 -
121Pd 120.92887(54)# 400# ms [>300 ns] β- to 122Ag N/A N/A 1000.44 -
122Pd 121.93055(43)# 300# ms [>300 ns] β- to 123Ag 0+ N/A 999.2 -
123Pd 122.93493(64)# 200# ms [>300 ns] β- to 124Ag N/A N/A 1007.28 -
124Pd 123.93688(54)# 100# ms [>300 ns] Unknown 0+ N/A 1015.36 -
125Pd 125 0.44(3) µs / 0.33(4) µs
(2 isomers)
Unknown N/A N/A N/A -
126Pd 126 5.8(8) µs Unknown N/A N/A N/A -
Palladium Elemental Symbol

Recent Research & Development for Palladium

  • Martin Deutges, Hans Peter Barth, Yuzeng Chen, Christine Borchers, Reiner Kirchheim, Hydrogen diffusivities as a measure of relative dislocation densities in palladium and increase of the density by plastic deformation in the presence of dissolved hydrogen, Acta Materialia, Volume 82, 1 January 2015
  • Koodlur Sannegowda Lokesh, Annemie Adriaens, Electropolymerization of palladium tetraaminephthalocyanine: Characterization and supercapacitance behavior, Dyes and Pigments, Volume 112, January 2015
  • Yuanyuan Cai, Xianfu Chen, Yi Wang, Minghui Qiu, Yiqun Fan, Fabrication of palladium–titania nanofiltration membranes via a colloidal sol–gel process, Microporous and Mesoporous Materials, Volume 201, 1 January 2015
  • Dong Chen, Penglei Cui, Hongyan He, Hui Liu, Jun Yang, Highly catalytic hollow palladium nanoparticles derived from silver@silver–palladium core–shell nanostructures for the oxidation of formic acid, Journal of Power Sources, Volume 272, 25 December 2014
  • Chongjiang Cao, Guang Yang, Wei Song, Xingrong Ju, Qiuhui Hu, Jianfeng Yao, Selective adsorption of palladium complex for carbon-supported Pd/Mo electrocatalyst by the charge enhanced dry impregnation method, Journal of Power Sources, Volume 272, 25 December 2014
  • Shan-Shan Li, Jie-Ning Zheng, Ai-Jun Wang, Fang-Lei Tao, Jiu-Ju Feng, Jian-Rong Chen, Haiying Yu, Branched platinum-on-palladium bimetallic heteronanostructures supported on reduced graphene oxide for highly efficient oxygen reduction reaction, Journal of Power Sources, Volume 272, 25 December 2014
  • Wei-Hsin Chen, Charng-Hung Lin, Yu-Li Lin, Flow-field design for improving hydrogen recovery in a palladium membrane tube, Journal of Membrane Science, Volume 472, 15 December 2014
  • Jindi Cai, Yanzhen Zeng, Yonglang Guo, Copper@palladium–copper core–shell nanospheres as a highly effective electrocatalyst for ethanol electro-oxidation in alkaline media, Journal of Power Sources, Volume 270, 15 December 2014
  • Jing-Jing Lv, Shan-Shan Li, Ai-Jun Wang, Li-Ping Mei, Jiu-Ju Feng, Jian-Rong Chen, Zhaojiang Chen, One-pot synthesis of monodisperse palladium–copper nanocrystals supported on reduced graphene oxide nanosheets with improved catalytic activity and methanol tolerance for oxygen reduction reaction, Journal of Power Sources, Volume 269, 10 December 2014
  • Jing-Jing Lv, Jie-Ning Zheng, Hong-Bao Zhang, Meng Lin, Ai-Jun Wang, Jian-Rong Chen, Jiu-Ju Feng, Simple synthesis of platinum–palladium nanoflowers on reduced graphene oxide and their enhanced catalytic activity for oxygen reduction reaction, Journal of Power Sources, Volume 269, 10 December 2014