Palladium

Palladium is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

More than half the supply of palladium and its congener platinum is used in catalytic converters, which convert as much as 90% of the harmful gases in automobile exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into less noxious substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification, chemical applications, groundwater treatment, and jewelry. Palladium is a key component of fuel cells, which react hydrogen with oxygen to produce electricity, heat, and water.

Ore deposits of palladium and other PGMs are rare. The most extensive deposits have been found in the norite belt of the Bushveld Igneous Complex covering the Transvaal Basin in South Africa; the Stillwater Complex in Montana, United States; the Sudbury Basin and Thunder Bay District of Ontario, Canada; and the Norilsk Complex in Russia. Recycling is also a source, mostly from scrapped catalytic converters. The numerous applications and limited supply sources result in considerable investment interest.

Palladium,  46Pd
Palladium (46 Pd)
Palladium
Pronunciation/pəˈleɪdiəm/ (pə-LAY-dee-əm)
Appearancesilvery white
Standard atomic weight Ar, std(Pd)106.42(1)[1]
Palladium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Ni

Pd

Pt
rhodiumpalladiumsilver
Atomic number (Z)46
Groupgroup 10
Periodperiod 5
Blockd-block
Element category  transition metal
Electron configuration[Kr] 4d10
Electrons per shell
2, 8, 18, 18
Physical properties
Phase at STPsolid
Melting point1828.05 K ​(1554.9 °C, ​2830.82 °F)
Boiling point3236 K ​(2963 °C, ​5365 °F)
Density (near r.t.)12.023 g/cm3
when liquid (at m.p.)10.38 g/cm3
Heat of fusion16.74 kJ/mol
Heat of vaporization358 kJ/mol
Molar heat capacity25.98 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1721 1897 2117 2395 2753 3234
Atomic properties
Oxidation states0, +1, +2, +3, +4 (a mildly basic oxide)
ElectronegativityPauling scale: 2.20
Ionization energies
  • 1st: 804.4 kJ/mol
  • 2nd: 1870 kJ/mol
  • 3rd: 3177 kJ/mol
Atomic radiusempirical: 137 pm
Covalent radius139±6 pm
Van der Waals radius163 pm
Color lines in a spectral range
Spectral lines of palladium
Other properties
Natural occurrenceprimordial
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for palladium
Speed of sound thin rod3070 m/s (at 20 °C)
Thermal expansion11.8 µm/(m·K) (at 25 °C)
Thermal conductivity71.8 W/(m·K)
Electrical resistivity105.4 nΩ·m (at 20 °C)
Magnetic orderingparamagnetic[2]
Magnetic susceptibility+567.4·10−6 cm3/mol (288 K)[3]
Young's modulus121 GPa
Shear modulus44 GPa
Bulk modulus180 GPa
Poisson ratio0.39
Mohs hardness4.75
Vickers hardness400–600 MPa
Brinell hardness320–610 MPa
CAS Number7440-05-3
History
Namingafter asteroid Pallas, itself named after Pallas Athena
Discovery and first isolationWilliam Hyde Wollaston (1802)
Main isotopes of palladium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
100Pd syn 3.63 d ε 100Rh
γ
102Pd 1.02% stable
103Pd syn 16.991 d ε 103Rh
104Pd 11.14% stable
105Pd 22.33% stable
106Pd 27.33% stable
107Pd trace 6.5×106 y β 107Ag
108Pd 26.46% stable
110Pd 11.72% stable

Characteristics

Palladium belongs to group 10 in the periodic table, but the configuration in the outermost electrons are in accordance with Hund's rule. Electrons in the s-shell migrate to fill the d orbitals because they have less energy.

Z Element No. of electrons/shell
28 nickel 2, 8, 16, 2 (or 2, 8, 17, 1)
46 palladium 2, 8, 18, 18
78 platinum 2, 8, 18, 32, 17, 1
110 darmstadtium 2, 8, 18, 32, 32, 16, 2 (predicted)

Palladium is a soft silver-white metal that resembles platinum. It is the least dense and has the lowest melting point of the platinum group metals. It is soft and ductile when annealed and is greatly increased in strength and hardness when cold-worked. Palladium dissolves slowly in concentrated nitric acid, in hot, concentrated sulfuric acid, and when finely ground, in hydrochloric acid.[4] It dissolves readily at room temperature in aqua regia.

Palladium does not react with oxygen at standard temperature (and thus does not tarnish in air). Palladium heated to 800 °C will produce a layer of palladium(II) oxide (PdO). It tarnishes lightly in a moist atmosphere containing sulfur.[5]

Palladium films with defects produced by alpha particle bombardment at low temperature exhibit superconductivity having Tc=3.2 K.[6]

Isotopes

Naturally occurring palladium is composed of seven isotopes, six of which are stable. The most stable radioisotopes are 107Pd with a half-life of 6.5 million years (found in nature), 103Pd with 17 days, and 100Pd with 3.63 days. Eighteen other radioisotopes have been characterized with atomic weights ranging from 90.94948(64) u (91Pd) to 122.93426(64) u (123Pd).[7] These have half-lives of less than thirty minutes, except 101Pd (half-life: 8.47 hours), 109Pd (half-life: 13.7 hours), and 112Pd (half-life: 21 hours).[8]

For isotopes with atomic mass unit values less than that of the most abundant stable isotope, 106Pd, the primary decay mode is electron capture with the primary decay product being rhodium. The primary mode of decay for those isotopes of Pd with atomic mass greater than 106 is beta decay with the primary product of this decay being silver.[8]

Radiogenic 107Ag is a decay product of 107Pd and was first discovered in 1978[9] in the Santa Clara[10] meteorite of 1976. The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. 107Pd versus Ag correlations observed in bodies, which have been melted since accretion of the solar system, must reflect the presence of short-lived nuclides in the early solar system.[11]

Compounds

Palladium compounds primarily exist in the 0 and +2 oxidation state. Other less common states are also recognized. Generally the compounds of palladium are more similar to those of platinum than those of any other element.

Alpha-palladium(II)-chloride-xtal-3D-balls
Pd6Cl12-from-xtal-1996-CM-3D-ellipsoids
Structure of α-PdCl2
Structure of β-PdCl2

Palladium(II)

Palladium(II) chloride is the principal starting material for other palladium compounds. It arises by the reaction of palladium with chlorine. It is used to prepare heterogeneous palladium catalysts such as palladium on barium sulfate, palladium on carbon, and palladium chloride on carbon.[12] Solutions of PdCl2 in nitric acid react with acetic acid to give palladium(II) acetate, also a versatile reagent. PdCl2 reacts with ligands (L) to give square planar complexes of the type PdCl2L2. One example of such complexes is the benzonitrile derivative PdX2(PhCN)2.[13][14]

PdCl2 + 2 L → PdCl2L2 (L = PhCN, PPh3, NH3, etc)

The complex bis(triphenylphosphine)palladium(II) dichloride is a useful catalyst.[15]

Palladium(0)

Palladium forms a range of zerovalent complexes with the formula PdL4, PdL3 and PdL2. For example, reduction of a mixture of PdCl2(PPh3)2 and PPh3 gives tetrakis(triphenylphosphine)palladium(0):[16]

2 PdCl2(PPh3)2 + 4 PPh3 + 5 N2H4 → 2 Pd(PPh3)4 + N2 + 4 N2H5+Cl

Another major palladium(0) complex, tris(dibenzylideneacetone)dipalladium(0) (Pd2(dba)3), is prepared by reducing sodium tetrachloropalladate in the presence of dibenzylideneacetone.[17]

Palladium(0), as well as palladium(II), are catalysts in coupling reactions, as has been recognized by the 2010 Nobel Prize in Chemistry to Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki. Such reactions are widely practiced for the synthesis of fine chemicals. Prominent coupling reactions include the Heck, Suzuki, Sonogashira coupling, Stille reactions, and the Kumada coupling. Palladium(II) acetate, tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3)4, and tris(dibenzylideneacetone)dipalladium(0) (Pd2(dba)3) serve either as catalysts or precatalysts.[18]

Other oxidation states

Although Pd(IV) compounds are comparatively rare, one example is sodium hexachloropalladate(IV), Na2[PdCl6]. A few compounds of palladium(III) are also known.[19] Palladium(VI) was claimed in 2002,[20][21] but subsequently disproven.[22][23]

Mixed valence palladium complexes exist, e.g. Pd4(CO)4(OAc)4Pd(acac)2 forms an infinite Pd chain structure, with alternatively interconnected Pd4(CO)4(OAc)4 and Pd(acac)2 units.[24]

History

William Hyde Wollaston noted the discovery of a new noble metal in July 1802 in his lab-book and named it palladium in August of the same year. Wollaston purified a quantity of the material and offered it, without naming the discoverer, in a small shop in Soho in April 1803. After harsh criticism from Richard Chenevix that palladium is an alloy of platinum and mercury, Wollaston anonymously offered a reward of £20 for 20 grains of synthetic palladium alloy.[25] Chenevix received the Copley Medal in 1803 after he published his experiments on palladium. Wollaston published the discovery of rhodium in 1804 and mentions some of his work on palladium.[26][27] He disclosed that he was the discoverer of palladium in a publication in 1805.[25][28]

It was named by Wollaston in 1802 after the asteroid 2 Pallas, which had been discovered two months earlier.[4] Wollaston found palladium in crude platinum ore from South America by dissolving the ore in aqua regia, neutralizing the solution with sodium hydroxide, and precipitating platinum as ammonium chloroplatinate with ammonium chloride. He added mercuric cyanide to form the compound palladium(II) cyanide, which was heated to extract palladium metal.[26]

Palladium chloride was at one time prescribed as a tuberculosis treatment at the rate of 0.065 g per day (approximately one milligram per kilogram of body weight). This treatment had many negative side-effects, and was later replaced by more effective drugs.[29]

Most palladium is used for catalytic converters in the automobile industry.[30] In the run up to year 2000, the Russian supply of palladium to the global market was repeatedly delayed and disrupted; for political reasons, the export quota was not granted on time.[31] The ensuing market panic drove the price to an all-time high of $1340 per troy ounce in January 2001.[32] Around that time, the Ford Motor Company, fearing that automobile production would be disrupted by a palladium shortage, stockpiled the metal. When prices fell in early 2001, Ford lost nearly US$1 billion.[33]

World demand for palladium increased from 100 tons in 1990 to nearly 300 tons in 2000. The global production of palladium from mines was 222 tonnes in 2006 according to the United States Geological Survey.[34] Many were concerned about a steady supply of palladium in the wake of Russia's military maneuvers in Ukraine, partly as sanctions could hamper Russian palladium exports; any restrictions on Russian palladium exports would exacerbate what is already expected to be a large palladium deficit in 2014.[35] Those concerns pushed palladium prices to their highest level since 2001.[36] In September 2014 they soared above the $900 per ounce mark. In 2016 however palladium cost around $614 per ounce as Russia managed to maintain stable supplies.[37] In January 2019 palladium futures climbed past $1,344 per ounce for the first time on record, mainly due to the strong demand from the automotive industry.[38]

Occurrence

2005palladium (mined)
Palladium output in 2005

As overall mine production of palladium reached 208,000 kilograms in 2016, Russia was the top producer with 82,000 kilograms, followed by South Africa, Canada and the U.S.[39] Russia's company Norilsk Nickel ranks first among the largest palladium producers globally, it accounts for 39% of the world’s production.[40]

Palladium can be found as a free metal alloyed with gold and other platinum-group metals in placer deposits of the Ural Mountains, Australia, Ethiopia, North and South America. For the production of palladium, these deposits play only a minor role. The most important commercial sources are nickel-copper deposits found in the Sudbury Basin, Ontario, and the Norilsk–Talnakh deposits in Siberia. The other large deposit is the Merensky Reef platinum group metals deposit within the Bushveld Igneous Complex South Africa. The Stillwater igneous complex of Montana and the Roby zone ore body of the Lac des Îles igneous complex of Ontario are the two other sources of palladium in Canada and the United States.[34][41] Palladium is found in the rare minerals cooperite[42] and polarite.[43] Many more Pd minerals are known, but all of them are very rare.[44]

Palladium is also produced in nuclear fission reactors and can be extracted from spent nuclear fuel (see synthesis of precious metals), though this source for palladium is not used. None of the existing nuclear reprocessing facilities are equipped to extract palladium from the high-level radioactive waste.[45]

Applications

25 rubles palladium 1989 Ivan III
The Soviet 25-rouble commemorative palladium coin is a rare example of the monetary usage of palladium.

The largest use of palladium today is in catalytic converters.[46] Palladium is also used in jewelry, dentistry,[46][47] watch making, blood sugar test strips, aircraft spark plugs, surgical instruments, and electrical contacts.[48] Palladium is also used to make professional transverse (concert or classical) flutes.[49] As a commodity, palladium bullion has ISO currency codes of XPD and 964. Palladium is one of only four metals to have such codes, the others being gold, silver and platinum.[50] Because it absorbs hydrogen, palladium is a key component of the controversial cold fusion experiments that began in 1989.

Catalysis

When it is finely divided, as with palladium on carbon, palladium forms a versatile catalyst; it speeds heterogeneous catalytic processes like hydrogenation, dehydrogenation, and petroleum cracking. Palladium is also essential to the Lindlar catalyst, also called Lindlar's Palladium.[51] A large number of carbon–carbon bonding reactions in organic chemistry are facilitated by palladium compound catalysts. For example:

(See palladium compounds and palladium-catalyzed coupling reactions.)

When dispersed on conductive materials, palladium is an excellent electrocatalyst for oxidation of primary alcohols in alkaline media.[52] Palladium is also a versatile metal for homogeneous catalysis, used in combination with a broad variety of ligands for highly selective chemical transformations.

In 2010, palladium-catalysed organic reactions were recognized by the Nobel Prize in Chemistry. A 2008 study showed that palladium is an effective catalyst for carbon-fluorine bonds.[53]

Kumada Catalytic Cycle
Catalytic cycle for Kumada cross coupling reaction, which is widely used in the synthesis of fine chemicals.

Palladium catalysis is primarily employed in organic chemistry and industrial applications, although its use is growing as a tool for synthetic biology; in 2017, effective in vivo catalytic activity of palladium nanoparticles was demonstrated in mammals to treat disease.[54]

Electronics

The second greatest application of palladium in electronics is in multilayer ceramic capacitors[55] in which palladium (and palladium-silver alloy) is used for electrodes.[46] Palladium (sometimes alloyed with nickel) is used for component and connector plating in consumer electronics[56][57] and in soldering materials. The electronic sector consumed 1.07 million troy ounces (33.2 tonnes) of palladium in 2006, according to a Johnson Matthey report.[58]

Technology

Hydrogen easily diffuses through heated palladium,[4] and membrane reactors with Pd membranes are used in the production of high purity hydrogen.[59] Palladium is used in palladium-hydrogen electrodes in electrochemical studies. Palladium(II) chloride readily catalyzes carbon monoxide gas to carbon dioxide and is useful in carbon monoxide detectors.[60]

Hydrogen storage

Palladium readily absorbs hydrogen at room temperatures, forming palladium hydride PdHx with x less than 1.[61] While this property is common to many transition metals, palladium has a uniquely high absorption capacity and does not lose its ductility until x approaches 1.[62] This property has been investigated in designing an efficient, inexpensive, and safe hydrogen fuel storage medium, though palladium itself is currently prohibitively expensive for this purpose.[63] The content of hydrogen in palladium can be linked to magnetic susceptibility, which decreases with the increase of hydrogen and becomes zero for PdH0.62. At any higher ratio, the solid solution becomes diamagnetic.[64]

Dentistry

Palladium is used in small amounts (about 0.5%) in some alloys of dental amalgam to decrease corrosion and increase the metallic lustre of the final restoration.[65]

Jewelry

Palladium has been used as a precious metal in jewelry since 1939 as an alternative to platinum in the alloys called "white gold", where the naturally white color of palladium does not require rhodium plating. Palladium is much less dense than platinum. Similar to gold, palladium can be beaten into leaf as thin as 100 nm (​1250,000 in).[4] Unlike platinum, palladium may discolor at temperatures above 400 °C (752 °F);[66] it is relatively brittle.

Prior to 2004, the principal use of palladium in jewelry was the manufacture of white gold. Palladium is one of the three most popular alloying metals in white gold (nickel and silver can also be used).[46] Palladium-gold is more expensive than nickel-gold, but seldom causes allergic reactions (though certain cross-allergies with nickel may occur).[67]

When platinum became a strategic resource during World War II, many jewelry bands were made out of palladium. Palladium was little used in jewelry because of the technical difficulty of casting. With the casting problem resolved the use of palladium in jewelry increased, originally because platinum increased in price while the price of palladium decreased.[68] In early 2004, when gold and platinum prices rose steeply, China began fabricating volumes of palladium jewelry, consuming 37 tonnes in 2005. Subsequent changes in the relative price of platinum lowered demand for palladium to 17.4 tonnes in 2009.[69][70] Demand for palladium as a catalyst has increased the price of palladium to about 50% higher than that of platinum in January 2019.[71]

In January 2010, hallmarks for palladium were introduced by assay offices in the United Kingdom, and hallmarking became mandatory for all jewelry advertising pure or alloyed palladium. Articles can be marked as 500, 950, or 999 parts of palladium per thousand of the alloy.

Fountain pen nibs made from gold are sometimes plated with palladium when a silver (rather than gold) appearance is desired. Sheaffer has used palladium plating for decades, either as an accent on otherwise gold nibs or covering the gold completely.

Photography

In the platinotype printing process, photographers make fine-art black-and-white prints using platinum or palladium salts. Often used with platinum, palladium provides an alternative to silver.[72]

Toxicity

Palladium
Hazards
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Warning
H317
P261, P273, P280, P302+352, P321, P333+313, P363, P501[73]
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chlorideReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
0
0

Palladium is a metal with low toxicity. It is poorly absorbed by the human body when ingested. Plants such as the water hyacinth are killed by low levels of palladium salts, but most other plants tolerate it, although tests show that, at levels above 0.0003%, growth is affected. High doses of palladium could be poisonous; tests on rodents suggest it may be carcinogenic, though no clear evidence indicates the element harms humans.[74]

Precautions

Like other platinum-group metals, bulk Pd is quite inert. Although contact dermatitis has been reported, data on the effects are limited. It has been shown that people with an allergic reaction to palladium also react to nickel, making it advisable to avoid the use of dental alloys containing palladium on those so allergic.[30][75][76][77][78]

Some palladium is emitted with the exhaust gases of cars with catalytic converters. Between 4 and 108 ng/km of palladium particulate is released by such cars, while the total uptake from food is estimated to be less than 2 µg per person a day. The second possible source of palladium is dental restoration, from which the uptake of palladium is estimated to be less than 15 µg per person per day. People working with palladium or its compounds might have a considerably greater uptake. For soluble compounds such as palladium chloride, 99% is eliminated from the body within 3 days.[30]

The median lethal dose (LD50) of soluble palladium compounds in mice is 200 mg/kg for oral and 5 mg/kg for intravenous administration.[30]

See also

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External links

American Palladium Eagle

The American Palladium Eagle is the official palladium bullion coin of the United States. Each coin has a face value of $25 and contains 99.95% fine palladium. It was authorized by the American Eagle Palladium Bullion Coin Act of 2010 which became Public Law 111-303 passed during the 111th United States Congress. The Palladium Eagle uses the same obverse design as the Mercury dime, Liberty wearing a winged hat, while its reverse design is based on Weinman’s 1907 American Institute of Architects (AIA) medal design.A bullion version sold directly to the United States Mint's authorized purchasers was released on September 25, 2017 and a proof version priced at $1,387.50 was released on September 6, 2018. Both offerings were met with a strong response; the 2017 bullion version sold out the day of release and within five minutes, sales of the 2018 proof version were suspended pending verification of the existing 14,782 of 15,000 maximum orders. Secondary market sales for the proof version were also strong on September 6th with many listings selling at a $600 premium over the Mint's asking price.

Canadian Tire Centre

Canadian Tire Centre (French: Centre Canadian Tire) is a multi-purpose indoor arena in Ottawa, Ontario, Canada, located in the western suburb of Kanata. It opened in January 1996 as The Palladium and was also known as Corel Centre from 1996 to 2006 and Scotiabank Place from 2006 to 2013.

The arena is primarily used for ice hockey, serving as the home arena of the Ottawa Senators of the National Hockey League (NHL) since its opening in 1996, and as a temporary home for the Ottawa 67's of the Ontario Hockey League during renovations at its arena. The arena is also used regularly for music concerts and has hosted events such as the Canadian Interuniversity Sport men's basketball championship and the 2009 World Junior Ice Hockey Championships.

Crown Melbourne

Crown Melbourne (also referred to as Crown Casino and Entertainment Complex) is a casino and resort located on the south bank of the Yarra River, in Melbourne, Australia. Crown Casino is a unit of Crown Limited, and the first casino of the now-international Crown brand.

Initially having opened in 1994 on the north bank of the Yarra, Crown Melbourne relocated and re–opened on the south bank of the Yarra, in 1997. It remains one of the central features of the Southbank precinct of the Melbourne central business district. The entire complex has a space of 510,000 m²—the equivalent to two city blocks—making it the largest casino complex in the Southern Hemisphere and one of the largest in the world. The complex also hosts four hotels, Crown Towers, Crown Promenade, and Crown Metropol, with a fourth hotel approved for construction which is expected to commence in 2018.

The casino is accessible by tram routes 12, 58, 96, 109 which all pass near Southern Cross railway station and the Melbourne City Centre.

Group 10 element

Group 10, numbered by current IUPAC style, is the group of chemical elements in the periodic table that consists of nickel (Ni), palladium (Pd), platinum (Pt), and perhaps also the chemically uncharacterized darmstadtium (Ds). All are d-block transition metals. All known isotopes of darmstadtium are radioactive with short half-lives, and are not known to occur in nature; only minute quantities have been synthesized in laboratories.

Like other groups, the members of this group show patterns in electron configuration, especially in the outermost shells, although for this group they are particularly weak, with palladium being an exceptional case. The relativistic stabilization of the 7s orbital is the explanation to the predicted electron configuration of darmstadtium, which, unusually for this group, conforms to that predicted by the Aufbau principle.

Hollywood Palladium

The Hollywood Palladium is a theater located at 6215 Sunset Boulevard in Hollywood, California. It was built in a Streamline Moderne, Art Deco style and includes an 11,200 square foot (1040 m²) dance floor including a mezzanine and a floor level with room for up to 4,000 people. The theater was listed on the National Register of Historic Places in 2016.

Isotopes of palladium

Naturally occurring palladium (46Pd) is composed of six stable isotopes, 102Pd, 104Pd, 105Pd, 106Pd, 108Pd, and 110Pd, although 102Pd and 110Pd are theoretically unstable. The most stable radioisotopes are 107Pd with a half-life of 6.5 million years, 103Pd with a half-life of 17 days, and 100Pd with a half-life of 3.63 days. Twenty-three other radioisotopes have been characterized with atomic weights ranging from 90.949 u (91Pd) to 123.937 u (124Pd). Most of these have half-lives that are less than a half an hour except 101Pd (half-life: 8.47 hours), 109Pd (half-life: 13.7 hours), and 112Pd (half-life: 21 hours).

The primary decay mode before the most abundant stable isotope, 106Pd, is electron capture and the primary mode after is beta decay. The primary decay product before 106Pd is rhodium and the primary product after is silver.

Radiogenic 107Ag is a decay product of 107Pd and was first discovered in the Santa Clara meteorite of 1978. The discoverers suggest that the coalescence and differentiation of iron-cored small planets may have occurred 10 million years after a nucleosynthetic event. 107Pd versus Ag correlations observed in bodies, which have clearly been melted since accretion of the solar system, must reflect the presence of short-lived nuclides in the early solar system.

London Palladium

The London Palladium () is a 2,286-seat Grade II* West End theatre located on Argyll Street in the City of Westminster. From the roster of stars who have played there and many televised performances, it is arguably the most famous theatre in London and the United Kingdom, especially for musical variety shows. The theatre has also hosted the Royal Variety Performance a record 42 times, most recently in 2018.

London Platinum and Palladium Market

The London Platinum and Palladium Market (LPPM) is an over-the-counter trading centre for platinum and palladium and a commodity trading association. London has always been a centre for the research in and development of most of the platinum group metals. Trade was established in the early 20th century, typically by existing dealers of gold and silver. The LPPM has been involved in fixing the world market prices of platinum and palladium since 1989.

Next-Generation Secure Computing Base

The Next-Generation Secure Computing Base (NGSCB; codenamed Palladium and also known as Trusted Windows) was a cancelled software architecture designed by Microsoft which aimed to provide users of the Windows operating system with better privacy, security, and system integrity. NGSCB was the result of years of research and development within Microsoft to create a secure computing solution that equaled the security of closed platforms such as set-top boxes while simultaneously preserving the backward compatibility, flexibility, and openness of the Windows operating system. The primary stated objective with NGSCB was to "protect software from software."Part of the Trustworthy Computing initiative when unveiled in 2002, NGSCB was expected to be integrated with the Windows Vista operating system, then known by its codename "Longhorn." NGSCB relied on hardware designed by members of the Trusted Computing Group to produce a parallel operation environment hosted by a new kernel called the "Nexus" that existed alongside Windows and provide new applications with features such as hardware-based process isolation, data encryption based on integrity measurements, authentication of a local or remote machine or software configuration, and encrypted paths for user authentication and graphics output. NGSCB would also facilitate the creation and distribution of digital rights management (DRM) policies pertaining the use of information.The technology was the subject of much controversy during its development, with critics contending that it could be used to impose restrictions on users, enforce vendor lock-in, and undermine fair use rights and open-source software. NGSCB was first demonstrated by Microsoft in 2003 at the Windows Hardware Engineering Conference before undergoing a revision in 2004 that would enable applications written prior to its development to benefit from its functionality. In 2005, reports stated that Microsoft would scale back its plans so that the company could ship its Windows Vista operating system by its target date of 2006. Development of NGSCB spanned almost a decade before its cancellation, one of the lengthiest development periods of a feature intended for the operating system.

NGSCB differed from the technologies that Microsoft billed as pillars of Windows Vista during development of the operating system, including Windows Presentation Foundation, Windows Communication Foundation, and WinFS, in that it was not built upon and did not prioritize .NET Framework managed code. While the technology has not fully materialized, aspects of NGSCB have emerged in Microsoft's BitLocker full disk encryption feature, which can optionally use the Trusted Platform Module to validate the integrity of boot and system files prior to operating system startup; the Measured Boot feature in Windows 8; the certificate attestation features in Windows 8.1; and the Device Guard feature of Windows 10.

Palladium(II) fluoride

Palladium(II) fluoride, also known as palladium difluoride, is the chemical compound of palladium and fluorine with the formula PdF2.

Palladium(II) oxide

Palladium(II) oxide is the inorganic compound of formula PdO. It is the only well characterised oxide of palladium. It is prepared by treating the metal with oxygen. Above about 900 °C, the oxide reverts to palladium metal and oxygen gas. It is not attacked by acids.

Palladium-Item

The Palladium-Item is the daily morning newspaper for Richmond, Indiana and surrounding areas. The paper is a merger of two older papers, the Richmond Palladium and the Richmond Item and traces its history back to 1831, making it the oldest continuous businesses in Richmond. It was sold in 1976 to the Gannett Company, and is currently part of the USA Today network of titles. Its News Director is Greg Fallon.Notable writers from the paper's staff include Mike Lopresti who is now a sports columnist for the Gannett News Service and is published in many of their papers.

Palladium (New York City)

The Palladium (originally called the Academy of Music) was a movie theatre, concert hall, and finally nightclub in New York City. It was located on the south side of East 14th Street, between Irving Place and Third Avenue.

Designed by Thomas W. Lamb, it was built in 1927 across the street from the site of the original Academy of Music established by financier Moses H. Grinnell in 1852. Opened as a deluxe movie palace by movie mogul William Fox, the Academy operated as a cinema through the early 1970s.

Beginning in the 1960s, it was also utilized as a rock concert venue, particularly following the 1971 closure of the Fillmore East. It was rechristened the Palladium on September 18, 1976, with The Band live radio broadcast, and continued to serve as a concert hall into the following decade.

In 1985, the Palladium was converted into a nightclub by Steve Rubell and Ian Schrager, after their success with Studio 54. Japanese architect Arata Isozaki redesigned the building's interior for the club.In 1997, the Palladium closed and was later demolished. New York University purchased the land and built a 12-story residence hall retaining the name Palladium. The residence hall typically houses 975 undergraduate and 170 MBA students. Two floors in the basement and sub-basement are dedicated to the Palladium Athletic Facility, also known to the University community by its nickname, "Pally."

Palladium (classical antiquity)

In Greek and Roman mythology, the palladium or palladion was a cult image of great antiquity on which the safety of Troy and later Rome was said to depend, the wooden statue (xoanon) of Pallas Athena that Odysseus and Diomedes stole from the citadel of Troy and which was later taken to the future site of Rome by Aeneas. The Roman story is related in Virgil's Aeneid and other works. Rome possessed an object regarded as the actual Palladium for several centuries; it was in the care of the Vestal Virgins for nearly all this time.

In English, since around 1600, the word palladium has been used figuratively to mean anything believed to provide protection or safety, and in particular in Christian contexts a sacred relic or icon believed to have a protective role in military contexts for a whole city, people or nation. Such beliefs first become prominent in the Eastern church in the period after the reign of the Byzantine Emperor Justinian I, and later spread to the Western church. Palladia were carried in procession around the walls of besieged cities and sometimes carried into battle.

Palladium Books

Palladium Books is a publisher of role-playing games (RPGs) perhaps best known for its popular, expansive Rifts series (1990–present). Palladium was founded April 1981 in Detroit, Michigan by current president and lead game designer Kevin Siembieda, and is now based in Westland, Michigan. The company enjoys the support of a small but dedicated fanbase who praise its various game series for their innovative settings and ease of adaptability to various personal preferences, play styles, and power levels.

Precious metal

A precious metal is a rare, naturally occurring metallic chemical element of high economic value.

Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lustre. Historically, precious metals were important as currency but are now regarded mainly as investment and industrial commodities. Gold, silver, platinum, and palladium each have an ISO 4217 currency code.

The best known precious metals are the coinage metals, which are gold and silver. Although both have industrial uses, they are better known for their uses in art, jewelry, and coinage. Other precious metals include the platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded.

The demand for precious metals is driven not only by their practical use but also by their role as investments and a store of value. Historically, precious metals have commanded much higher prices than common industrial metals.

Rhodium

Rhodium is a chemical element with symbol Rh and atomic number 45. It is a rare, silvery-white, hard, corrosion-resistant, and chemically inert transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope, 103Rh. Naturally occurring rhodium is usually found as the free metal, alloyed with similar metals, and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals.

Rhodium is found in platinum or nickel ores together with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds, produced after it reacted with the powerful acid mixture aqua regia.

The element's major use (approximately 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters in automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals, and because of its rarity, rhodium is usually alloyed with platinum or palladium and applied in high-temperature and corrosion-resistive coatings. White gold is often plated with a thin rhodium layer to improve its appearance while sterling silver is often rhodium-plated for tarnish resistance.

Rhodium detectors are used in nuclear reactors to measure the neutron flux level.

The Herald-Palladium

The Herald-Palladium is a newspaper distributed in the Southwest Michigan region serving all or part of Berrien, Cass, Van Buren, and Allegan Counties.

Tonight at the London Palladium

Tonight at the London Palladium is a British television variety show that is hosted from the London Palladium theatre in London's West End. Originally produced by ATV for the ITV network from 1955 to 1969, it went by its original name Sunday Night at the London Palladium from 25 September 1955 until the name was changed to The London Palladium Show from 1966 to 2 February 1969.

It underwent three revivals, first from 28 October 1973 to 28 October 1974 where it retained its Sunday Night at the London Palladium title, second in 2000 under the title Tonight at the London Palladium, and third from 2014 until 2015 under the title Sunday Night at the Palladium, dropping London. From 2016, the show is called Tonight at the London Palladium and is presented by Bradley Walsh.

A one-off Sunday Night at the London Palladium was screened to mark Bruce Forsyth's 70th birthday in February 1998.

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