Leipzig is the most populous city in the federal state of Saxony, Germany. With a population of 581,980 inhabitants as of 2017, it is Germany's tenth most populous city. Leipzig is located about 160 kilometres southwest of Berlin at the confluence of the White Elster, Pleiße and Parthe rivers at the southern end of the North German Plain. Leipzig has been a trade city since at least the time of the Holy Roman Empire; the city sits at the intersection of the Via Regia and the Via Imperii, two important medieval trade routes. Leipzig was once one of the major European centers of learning and culture in fields such as music and publishing. Leipzig became a major urban center within the German Democratic Republic after the Second World War, but its cultural and economic importance declined. Events in Leipzig in 1989 played a significant role in precipitating the fall of communism in Central and Eastern Europe through demonstrations starting from St. Nicholas Church. Since the reunification of Germany, Leipzig has undergone significant change with the restoration of some historical buildings, the demolition of others, the development of a modern transport infrastructure.
Leipzig today is an economic centre, the most livable city in Germany, according to the GfK marketing research institution and has the second-best future prospects of all cities in Germany, according to HWWI and Berenberg Bank. Leipzig Zoo is one of the most modern zoos in Europe and ranks first in Germany and second in Europe according to Anthony Sheridan. Since the opening of the Leipzig City Tunnel in 2013, Leipzig forms the centrepiece of the S-Bahn Mitteldeutschland public transit system. Leipzig is listed as a Gamma World City, Germany's "Boomtown" and as the European City of the Year 2019. Leipzig has long been a major center for music, both classical as well as modern "dark alternative music" or darkwave genres; the Oper Leipzig is one of the most prominent opera houses in Germany. It was founded in 1693, making it the third oldest opera venue in Europe after La Fenice and the Hamburg State Opera. Leipzig is home to the University of Music and Theatre "Felix Mendelssohn Bartholdy", it was during a stay in this city that Friedrich Schiller wrote his poem "Ode to Joy".
The Leipzig Gewandhaus Orchestra, established in 1743, is one of the oldest symphony orchestras in the world. Johann Sebastian Bach is one among many major composers who lived in Leipzig; the name Leipzig is derived from the Slavic word Lipsk, which means "settlement where the linden trees stand". An older spelling of the name in English is Leipsic; the Latin name Lipsia was used. The name is cognate with Lipetsk in Liepāja in Latvia. In 1937 the Nazi government renamed the city Reichsmessestadt Leipzig. Since 1989 Leipzig has been informally dubbed "Hero City", in recognition of the role that the Monday demonstrations there played in the fall of the East German regime – the name alludes to the honorary title awarded in the former Soviet Union to certain cities that played a key role in the victory of the Allies during the Second World War; the common usage of this nickname for Leipzig up until the present is reflected, for example, in the name of a popular blog for local arts and culture, Heldenstadt.de.
More the city has sometimes been nicknamed the "Boomtown of eastern Germany", "Hypezig" or "The better Berlin" for being celebrated by the media as a hip urban centre for the vital lifestyle and creative scene with many startups. Leipzig was first documented in 1015 in the chronicles of Bishop Thietmar of Merseburg as urbs Libzi and endowed with city and market privileges in 1165 by Otto the Rich. Leipzig Trade Fair, started in the Middle Ages, has become an event of international importance and is the oldest surviving trade fair in the world. There are records of commercial fishing operations on the river Pleiße in Leipzig dating back to 1305, when the Margrave Dietrich the Younger granted the fishing rights to the church and convent of St Thomas. There were a number of monasteries in and around the city, including a Franciscan monastery after which the Barfußgäßchen is named and a monastery of Irish monks near the present day Ranstädter Steinweg; the foundation of the University of Leipzig in 1409 initiated the city's development into a centre of German law and the publishing industry, towards being the location of the Reichsgericht and the German National Library.
During the Thirty Years' War, two battles took place in Breitenfeld, about 8 kilometres outside Leipzig city walls. The first Battle of Breitenfeld took place in 1631 and the second in 1642. Both battles resulted in victories for the Swedish-led side. On 24 December 1701, an oil-fueled street lighting system was introduced; the city employed light guards who had to follow a specific schedule to ensure the punctual lighting of the 700 lanterns. The Leipzig region was the arena of the 1813 Battle of Leipzig between Napoleonic France and an allied coalition of Prussia, Russia and Sweden, it was the largest battle in Europe before the First World War and the coalition victory ended Napoleon's presence in Germany and would lead to his first exile on Elba. The Monument to the Battle of the Nations celebrating the centenary of this event was completed in 1913. In addition to stimulating German nationalism, the war had a major impact in mobilizing a civic spirit in numerous volunteer activities. Many volunteer militi
A consumer is a person or organization that uses economic services or commodities. A consumer is the one who pays something to consume services produced; as such, consumers play a vital role in the economic system of a nation. Without consumer demand, producers would lack one of the key motivations to produce: to sell to consumers; the consumer forms part of the chain of distribution. In marketing instead of marketers generating broad demographic profiles and Fisio-graphic profiles of market segments, marketers have started to engage in personalized marketing, permission marketing, mass customization. Due to the rise of the Internet, consumers are shifting more and more towards becoming "prosumers", consumers who are producers, influence the products created participate in the production process, or use interactive products; the law uses a notion of the consumer in relation to consumer protection laws, the definition of consumer is restricted to living persons and excludes commercial users. A typical legal rationale for protecting the consumer is based on the notion of policing market failures and inefficiencies, such as inequalities of bargaining power between a consumer and a business.
As all potential voters are consumers, consumer protection has a clear political significance. Concern over the interests of consumers has spawned consumer activism, where organized activists do research and advocacy to improve the offer of products and services. Consumer education has been incorporated into some school curricula. There are various non-profit publications, such as Which?, Consumer Reports and Choice Magazine, dedicated to assist in consumer education and decision making. In India, the Consumer Protection Act 1986 differentiates the consummation of a commodity or service for personal use or to earn a livelihood. Only consumers are protected per this act and any person, entity or organization purchasing a commodity for commercial reasons are exempted from any benefits of this act. U. S. Government National Consumer Protection Week
Silver is a chemical element with symbol Ag and atomic number 47. A soft, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, reflectivity of any metal; the metal is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold and zinc refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal, its purity is measured on a per-mille basis. As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Other than in currency and as an investment medium, silver is used in solar panels, water filtration, ornaments, high-value tableware and utensils, in electrical contacts and conductors, in specialized mirrors, window coatings, in catalysis of chemical reactions, as a colorant in stained glass and in specialised confectionery.
Its compounds are used in X-ray film. Dilute solutions of silver nitrate and other silver compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings and other medical instruments. Silver is similar in its physical and chemical properties to its two vertical neighbours in group 11 of the periodic table and gold, its 47 electrons are arranged in the configuration 4d105s1 to copper and gold. This distinctive electron configuration, with a single electron in the highest occupied s subshell over a filled d subshell, accounts for many of the singular properties of metallic silver. Silver is an soft and malleable transition metal, though it is less malleable than gold. Silver crystallizes in a face-centered cubic lattice with bulk coordination number 12, where only the single 5s electron is delocalized to copper and gold. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are weak; this observation explains the low high ductility of single crystals of silver.
Silver has a brilliant white metallic luster that can take a high polish, and, so characteristic that the name of the metal itself has become a colour name. Unlike copper and gold, the energy required to excite an electron from the filled d band to the s-p conduction band in silver is large enough that it no longer corresponds to absorption in the visible region of the spectrum, but rather in the ultraviolet. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm. High electrical and thermal conductivity is common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions lower electron mobility; the electrical conductivity of silver is the greatest of all metals, greater than copper, but it is not used for this property because of the higher cost.
An exception is in radio-frequency engineering at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior. During World War II in the US, 13540 tons of silver were used in electromagnets for enriching uranium because of the wartime shortage of copper. Pure silver has the highest thermal conductivity of any metal, although the conductivity of carbon and superfluid helium-4 are higher. Silver has the lowest contact resistance of any metal. Silver forms alloys with copper and gold, as well as zinc. Zinc-silver alloys with low zinc concentration may be considered as face-centred cubic solid solutions of zinc in silver, as the structure of the silver is unchanged while the electron concentration rises as more zinc is added. Increasing the electron concentration further leads to body-centred cubic, complex cubic, hexagonal close-packed phases. Occurring silver is composed of two stable isotopes, 107Ag and 109Ag, with 107Ag being more abundant.
This equal abundance is rare in the periodic table. The atomic weight is 107.8682 u. Both isotopes of silver are produced in stars via the s-process, as well as in supernovas via the r-process. Twenty-eight radioisotopes have been characterized, the most stable being 105Ag with a half-life of 41.29 days, 111Ag with a half-life of 7.45 days, 112Ag with a half-life of 3.13 hours. Silver has numerous nuclear isomers, the most stable being 108mAg, 110mAg and 106mAg. All of the remaining radioactive isotopes have half-lives of less than an hour, the majority of these have half-lives of less than three minutes. Isotopes of silver range in relative atomic mass from 92.950 u
The Denver Mint is a branch of the United States Mint that struck its first coins on February 1, 1906. The mint is still operating and producing coins for circulation, as well as mint sets and commemorative coins. Coins produced at the Denver Mint bear a D mint mark; the Denver Mint is the single largest producer of coins in the world.. The predecessors of the Denver Mint were the men of Clark and Company. During the Pikes Peak Gold Rush, they coined gold dust brought from the gold fields by the miners. In 1858, Austin M. Clark, Milton E. Clark and Emanuel Henry Gruber founded a brokerage firm in Leavenworth and established an office in Denver at the beginning of the Colorado Gold Rush. Desiring to save on shipping and insurance costs associated with shipping gold back east, the firm opened a private mint. On 25 July 1860, the mint opened in a two-story brick building on the corner of Market and 16th Streets, minting $10 gold pieces at the rate of "fifteen or twenty coins a minute". "On the face is a representation of the peak, its base surrounded by a forest of timber and'Pikes Peak Gold' encircling the summit.
Under its base is the word'Denver', beneath it'Ten D.'. On the reverse is the American Eagle encircled by the name of the firm'Clark, Gruber & Co.', beneath the date,'1860'."A $20 gold coin was added, "the weight will be greater, but the value the same as the United States coin of like denomination". A $5 and a $2.5 gold coin were added, with production reaching $18,000 per week. On the front was the "head of the Goddess of Liberty surrounded by thirteen stars, with "Clark & Company" in the tiara. "Pikes's Peak Gold, Denver" was on the other side, with "5D." or "2 1/2 D."In the three years of operation, they minted $594,305 worth of Pike's Peak Gold in the form of gold coins. Additionally, they purchased 77,000 troy ounces of raw gold, shipped "large amounts of dust" to the Philadelphia Mint; the building and minting equipment was formally bought by the US Treasury in April 1863. Clark, Gruber & Co. remained a bank until bought by the First National Bank of Denver in 1865. Established by an Act of Congress on April 21, 1862, the United States Mint at Denver opened for business in late 1863 as a United States Assay Office.
Operations began in the facilities of Clark and Company, located at 16th and Market Streets and acquired by the government for $25,000, which it was able to print off at the location. Unlike Clark and Company, the Denver plant performed no coinage of gold as first intended. One reason given by the Director of the Mint for the lack of coinage at Denver was, "…the hostility of the Indian tribes along the routes, doubtless instigated by rebel emissaries and bad white men." Gold and nuggets brought there by miners from the surrounding area were accepted by the Assay Office for melting and stamping of cast gold bars. The bars were returned to the depositors as imparted bars stamped with the weight and fineness of the gold. Most of the gold came from the rich beds of placer gold found in the streams and first discovered in 1858, the same year Denver was founded; when the supply of gold was exhausted from the streams, the emphasis turned to lode mining, uncovering veins of ore with a high percentage of gold and silver.
By 1859, the yearly value of the gold and silver deposited at the Assay Office was over $5.6 million. During its early years as an Assay Office, the Denver plant was the city's most substantial structure; the United States Treasury did not expand its smelting and refining operations at the same rate as the discovery and production of gold. In 1872 a group of businessmen led by Judge Hiram Bond, Joseph Miner and Denver Mayor Joseph E. Bates set up a firm Denver Smelting and Refining Works which built an independent complementary plant which processed ore into ingots which were assayed and stamped by the Denver Mint. There was new hope for branch mint status when Congress provided for the establishment of a mint at Denver for gold and silver coin production; the site for the new mint at West Colfax and Delaware streets was purchased on April 22, 1896, for $60,000. Construction began in 1897. Appropriations to complete and equip the plant were insufficient, the transfer of assay operations to the new building were delayed until September 1, 1904.
Coinage operations began on February 1, 1906, advancing the status of the Denver facility to Branch Mint. In addition, before the new machinery to be used at the Mint was installed for use, it was first sent to the St. Louis Exposition of 1904 for display. Silver coins were minted in Denver for the first time in 1906. During the first year, 167 million coins were produced, including $20 gold coins, $10 gold coins, $5 gold coins, assorted denominations of silver coins; the Denver Mint is mentioned in The Andy Griffith Show episode "A Black Day for Mayberry". The Denver Mint is featured in the 1993 Sylvester Stallone film Cliffhanger, as the production point of the money stolen in the film, the departure point for the plane; the Mint is mentioned in both the title and lyrics of the Jimmy Eat World song "Lucky Denver Mint". The Denver Mint appears anachronistically in the 1870s in the 1967 The Wild Wild West episode "The Night of the Circus of Death". To above, The Mint is anachronistically set in the 1870s in the 1960 Shotgun Slade episode "The Missing Train".
The 1960 episode "Cold Hard Cash" of The Rifleman, set a few ye
A metallurgical assay is a compositional analysis of an ore, metal, or alloy. Some assay methods are suitable for raw materials. Raw precious metals are assayed by an assay office. Silver is assayed by titration, gold by cupellation and platinum by inductively coupled plasma optical emission spectrometry. Precious metal items of art or jewelry are hallmarked. Where required to be hallmarked, semi-finished precious metal items of art or jewelry pass through the official testing channels where they are analyzed or assayed for precious metal content. While different nations permit a variety of acceptable finenesses, the assayer is testing to determine that the fineness of the product conforms with the statement or claim of fineness that the maker has claimed on the item. In the past the assay was conducted by using the touchstone method but it is done using X-ray fluorescence. XRF is used; the most exact method of assay is known as fire cupellation. This method is better suited for the assay of bullion and gold stocks rather than works of art or jewelry because it is a destructive method.
The age-old touchstone method is suited to the testing of valuable pieces, for which sampling by destructive means, such as scraping, cutting or drilling is unacceptable. A rubbing of the item is made on a special stone, treated with acids and the resulting color compared to references. Red radiolarian chert or black siliceous slate were used to view the resultant treated streak of the sample. Differences in precious metal content as small as 10 to 20 parts per thousand can be established with confidence by the test, it is not indicated for use with white gold, for example, since the color variation among white gold alloys is imperceptible. The modern X-ray fluorescence is a non-destructive technique, suitable for normal assaying requirements, it has an accuracy of 2 to 5 parts per thousand and is well-suited to flat and large surfaces. It is a quick technique taking about three minutes, the results can be automatically printed out by computer, it measures the content of the other alloying metals present.
It is not indicated, for articles with chemical surface treatment or electroplating. The process for X-ray fluorescence assay involves melting the material in a furnace and stirring to make a homogeneous mix. Following this, a sample is taken from the centre of the molten sample. Samples are taken using a vacuum pin tube; the sample is tested by X-Ray Fluorescence Spectroscopy. Metallurgical assay is completed in this way to ensure that an accurate assay is performed. X-ray Fluorescence assay is not as accurate as fire-assay but dependent on the spectrometer used, can achieve results of within 1 percent; the most elaborately accurate, but destructive, precious metal assay is fire-assay. If performed on bullion to international standards, the method can be accurate on gold metal to 1 part in 10,000. If performed on ore materials using fusion followed by cupellation separation, detection may be in parts per billion. However, accuracy on ore material is limited to 3 to 5% of reported value. Although time consuming, the method is the accepted standard applied for valuing gold ore as well as gold and silver bullion at major refineries and gold mining companies.
In the case of fire assaying of gold and platinum ores, the lengthy time required to carry out an assay is offset by carrying out large numbers of assays and a typical laboratory will be equipped with several fusion and cupellation furnaces, each capable of taking multiple samples, so that several hundred analyses per day can be carried out. The principal advantage of fire assay is that large samples can be used, these increase the accuracy in analysing low yield ores in the <1g/T range of concentration. Fusion: the process requires a self-generating reducing atmosphere, so the crushed ore sample is mixed with fluxes and a carbon source mixed with powdered lead oxide in a refractory crucible. In general, multiple crucibles will be placed inside an electric furnace fitted with silicon carbide heating elements, heated to between 1000–1200 °C; the temperature required, the type of flux used, are dependent on the composition of the rock in which the precious metals are concentrated, in many laboratories an empirical approach based on long experience is used.
A complex reaction takes place, whereby the carbon source reduces the lead oxide to lead, which alloys with the precious metals: at the same time, the fluxes combine with the crushed rock, reducing its melting point and forming a glassy slag. When fusion is complete, the sample is tipped into a mold where the slag floats to the top, the lead, now alloyed with the precious metals, sinks to the bottom, forming a'button'. After solidification, the samples are knocked out, the lead bullets recovered for cupellation, or for analysis by other means. Method details for various fire assay procedures vary, but concentration and separation chemistry comply with traditions set by Bugby or Shepard & Dietrich in the early 20th century. Method advancements since that time automate material handling and final finish measurements (i.e. instrument finish r
Platinum is a chemical element with symbol Pt and atomic number 78. It is a dense, ductile unreactive, silverish-white transition metal, its name is derived from the Spanish term platino, meaning "little silver". Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements, it has six occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of 5 μg/kg, it occurs in some nickel and copper ores along with some native deposits in South Africa, which accounts for 80% of the world production. Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, given its important uses, it is valuable and is a major precious metal commodity. Platinum is one of the least reactive metals, it has remarkable resistance to corrosion at high temperatures, is therefore considered a noble metal. Platinum is found chemically uncombined as native platinum; because it occurs in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts.
It was referenced in European writings as early as 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, jewelry. Being a heavy metal, it leads to health problems upon exposure to its salts. Compounds containing platinum, such as cisplatin and carboplatin, are applied in chemotherapy against certain types of cancer; as of 2018, the value of platinum is $833.00 per ounce. Pure platinum is a lustrous and malleable, silver-white metal. Platinum is more ductile than gold, silver or copper, thus being the most ductile of pure metals, but it is less malleable than gold; the metal has excellent resistance to corrosion, is stable at high temperatures and has stable electrical properties. Platinum does oxidize, forming PtO2, at 500 °C, it reacts vigorously with fluorine at 500 °C to form platinum tetrafluoride.
It is attacked by chlorine, bromine and sulfur. Platinum is insoluble in hydrochloric and nitric acid, but dissolves in hot aqua regia, to form chloroplatinic acid, H2PtCl6, its physical characteristics and chemical stability make it useful for industrial applications. Its resistance to wear and tarnish is well suited to use in fine jewellery; the most common oxidation states of platinum are +2 and +4. The +1 and +3 oxidation states are less common, are stabilized by metal bonding in bimetallic species; as is expected, tetracoordinate platinum compounds tend to adopt 16-electron square planar geometries. Although elemental platinum is unreactive, it dissolves in hot aqua regia to give aqueous chloroplatinic acid: Pt + 4 HNO3 + 6 HCl → H2PtCl6 + 4 NO2 + 4 H2OAs a soft acid, platinum has a great affinity for sulfur, such as on dimethyl sulfoxide. In 2007, Gerhard Ertl won the Nobel Prize in Chemistry for determining the detailed molecular mechanisms of the catalytic oxidation of carbon monoxide over platinum.
Platinum has six occurring isotopes: 190Pt, 192Pt, 194Pt, 195Pt, 196Pt, 198Pt. The most abundant of these is 195 Pt, it is the only stable isotope with a non-zero spin. 190Pt is the least abundant at only 0.01%. Of the occurring isotopes, only 190Pt is unstable, though it decays with a half-life of 6.5×1011 years, causing an activity of 15 Bq/kg of natural platinum. 198 Pt can undergo alpha decay. Platinum has 31 synthetic isotopes ranging in atomic mass from 166 to 204, making the total number of known isotopes 39; the least stable of these is 166Pt, with a half-life of 300 µs, whereas the most stable is 193Pt with a half-life of 50 years. Most platinum isotopes decay by some combination of beta alpha decay. 188Pt, 191Pt, 193Pt decay by electron capture. 190Pt and 198Pt are predicted to have energetically favorable double beta decay paths. Platinum is an rare metal, occurring at a concentration of only 0.005 ppm in Earth's crust. It is sometimes mistaken for silver. Platinum is found chemically uncombined as native platinum and as alloy with the other platinum-group metals and iron mostly.
Most the native platinum is found in secondary deposits in alluvial deposits. The alluvial deposits used by pre-Columbian people in the Chocó Department, Colombia are still a source for platinum-group metals. Another large alluvial deposit is in the Ural Mountains, it is still mined. In nickel and copper deposits, platinum-group metals occur as sulfides, tellurides and arsenides, as end alloys with nickel or copper. Platinum arsenide, sperrylite, is a major source of platinum associated with nickel ores in the Sudbury Basin deposit in Ontario, Canada. At Platinum, about 17,000 kg was mined between 1927 and 1975; the mine ceased operations in 1990. The rare sulfide minera
Palladium is a chemical element with symbol Pd and atomic number 46. It is a lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston, he named it after the asteroid Pallas, itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, rhodium, ruthenium and osmium form a group of elements referred to as the platinum group metals; 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 into less noxious substances. Palladium is used in electronics, medicine, hydrogen purification, chemical applications, groundwater treatment, jewelry. Palladium is a key component of fuel cells, which react hydrogen with oxygen to produce electricity 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.
Recycling is a source from scrapped catalytic converters. The numerous applications and limited supply sources result in considerable investment interest. 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. Palladium is a soft silver-white metal, it has the lowest melting point of the platinum group metals. It is soft and ductile when annealed and is increased in strength and hardness when cold-worked. Palladium dissolves in concentrated nitric acid, in hot, concentrated sulfuric acid, when finely ground, in hydrochloric acid, it dissolves at room temperature in aqua regia. Palladium does not react with oxygen at standard temperature. Palladium heated to 800 °C will produce a layer of palladium oxide, it tarnishes in a moist atmosphere containing sulfur. Palladium films with defects produced by alpha particle bombardment at low temperature exhibit superconductivity having Tc=3.2 K.
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, 103Pd with 17 days, 100Pd with 3.63 days. Eighteen other radioisotopes have been characterized with atomic weights ranging from 90.94948 u to 122.93426 u. These have half-lives of less than thirty minutes, except 101Pd, 109Pd, 112Pd. 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. Radiogenic 107Ag is a decay product of 107Pd and was first discovered in 1978 in the Santa Clara 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.
Palladium compounds exist in the 0 and +2 oxidation state. Other less common states are recognized; the compounds of palladium are more similar to those of platinum than those of any other element. Palladium 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, palladium chloride on carbon. Solutions of PdCl2 in nitric acid react with acetic acid to give palladium acetate a versatile reagent. PdCl2 reacts with ligands to give square planar complexes of the type PdCl2L2. One example of such complexes is the benzonitrile derivative PdX22. PdCl2 + 2 L → PdCl2L2. Palladium forms a range of zerovalent complexes with the formula PdL4, PdL3 and PdL2. For example, reduction of a mixture of PdCl22 and PPh3 gives tetrakispalladium: 2 PdCl22 + 4 PPh3 + 5 N2H4 → 2 Pd4 + N2 + 4 N2H5+Cl−Another major palladium complex, trisdipalladium, is prepared by reducing sodium tetrachloropalladate in the presence of dibenzylideneacetone.
Palladium, as well as palladium, are catalysts in coupling reactions, as has been recognized by the 2010 Nobel Prize in Chemistry to Richard F. Heck, Ei-ichi Negishi, Akira Suzuki; such reactions are practiced for the synthesis of fine chemicals. Prominent coupling reactions include the Heck, Sonogashira coupling, Stille reactions, the Kumada coupling. Palladium acetate, tetrakispalladium (Pd4, trisdipalladium serve either as catalysts or precatalysts. Although Pd compounds are comparatively rare, one example is sodium hexachloropalladate