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Platinum Group Metals
The platinum-group metals (PGMs) are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block (groups 8, 9, and 10, periods 5 and 6). The six platinum-group metals are ruthenium, rhodium, palladium, osmium, iridium, and platinum. They have similar physical and chemical properties, and tend to occur together in the same mineral deposits. However, they can be further subdivided into the ''iridium-group platinum-group elements'' (IPGEs: Os, Ir, Ru) and the ''palladium-group platinum-group elements'' (PPGEs: Rh, Pt, Pd) based on their behaviour in geological systems. The three elements above the platinum group in the periodic table (iron, nickel and cobalt) are all ferromagnetic; these, together with the lanthanide element gadolinium (at temperatures below 20 °C), are the only known transition metals that display ferromagnetism near room temperature. History Naturally occurring platinum an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodic Table
The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows (" periods") and columns (" groups"). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics. Vertical, horizontal and diagonal trends characterize the periodic table. Metallic character increases going down a group and from right to left across a period. Nonmetallic character increases going from the bottom left of the periodic table to the top right. The first periodic table to become generally accepted was that of the Russian chemist Dmitri Mendeleev in 1869; he formulated the periodic law as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iridium
Iridium is a chemical element; it has the symbol Ir and atomic number 77. This very hard, brittle, silvery-white transition metal of the platinum group, is considered the second-densest naturally occurring metal (after osmium) with a density of as defined by experimental X-ray crystallography. 191Ir and 193Ir are the only two naturally occurring isotopes of iridium, as well as the only stable isotopes; the latter is the more abundant. It is one of the most corrosion-resistant metals, even at temperatures as high as . Iridium was discovered in 1803 in the acid-insoluble residues of platinum ores by the English chemist Smithson Tennant. The name ''iridium'', derived from the Greek word ''iris'' (rainbow), refers to the various colors of its compounds. Iridium is one of the rarest elements in Earth's crust, with an estimated annual production of only in 2023. The dominant uses of iridium are the metal itself and its alloys, as in high-performance spark plugs, crucibles for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troy Ounce
Troy weight is a system of units of mass that originated in the Kingdom of England in the 15th century and is primarily used in the precious metals industry. The troy weight units are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and the troy pound (12 troy ounces). The troy grain is equal to the grain unit of the avoirdupois system, but the troy ounce is heavier than the avoirdupois ounce, and the troy pound is lighter than the avoirdupois pound. Legally, one troy ounce (oz t) equals exactly 31.1034768 grams. Etymology Troy weight is generally supposed to take its name from the French market town of Troyes where English merchants traded at least as early as the early 9th century. The name ''troy'' is first attested in 1390, describing the weight of a platter, in an account of the travels in Europe of the Earl of Derby. Charles Moore Watson (1844–1916) proposes an alternative etymology: ''The Assize of Weights and Measures'' (also known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Prototype Kilogram K20 Replica
National may refer to: Common uses * Nation or country ** Nationality – a ''national'' is a person who is subject to a nation, regardless of whether the person has full rights as a citizen Places in the United States * National, Maryland, census-designated place * National, Nevada, ghost town * National, Utah, ghost town * National, West Virginia, unincorporated community Commerce * National (brand), a brand name of electronic goods from Panasonic * National Benzole (or simply known as National), former petrol station chain in the UK, merged with BP * National Book Store, a bookstore and office supplies chain in the Philippines * National Car Rental, an American rental car company * National Energy Systems, a former name of Eco Marine Power * National Entertainment Commission, a former name of the Media Rating Council * National Motor Vehicle Company, Indianapolis, Indiana, USA 1900–1924 * National Radio Company, Malden, Massachusetts, USA 1914–1991 * National Supermarke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smithson Tennant
Smithson Tennant Royal Society#Fellows, FRS (30 November 1761 – 22 February 1815) was an English chemist. He is best known for his discovery of the elements iridium and osmium, which he found in the residues from the solution of platinum ores in 1803. He also contributed to the proof of the identity of diamond and charcoal. The mineral tennantite is named after him. Life Tennant was born in Selby in Yorkshire. His father was Calvert Tennant (named after his grandmother Phyllis Calvert, a granddaughter of Cecilius Calvert, 2nd Baron Baltimore). His own name derives from his grandmother Rebecca Smithson, widow of Joshua Hitchling. He attended Beverley Grammar School and there is a plaque over one of the entrances to the present school commemorating his discovery of the two elements, osmium and iridium. He began to study medicine at University of Edinburgh, Edinburgh in 1781, but after a few months moved to Cambridge, where he devoted himself to botany and chemistry. He graduate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Hyde Wollaston
William Hyde Wollaston (; 6 August 1766 – 22 December 1828) was an English chemist and physicist who is famous for discovering the chemical elements palladium and rhodium. He also developed a way to process platinum ore into malleable ingots,Melvyn C. UsselmanWilliam Hyde WollastonEncyclopædia Britannica, retrieved 31 March 2013 patented the camera lucida, and made contributions in electricity and spectroscopy. Life He was born in East Dereham in Norfolk, the son of the Francis Wollaston (1737–1815), a noted amateur astronomer, and his wife Althea Hyde. He was one of 17 children, but the family was financially well-off and he enjoyed an intellectually stimulating environment. He was educated privately (and remotely) at Charterhouse School from 1774 to 1778 then studied Sciences at Gonville and Caius College, Cambridge. In 1793 he obtained his doctorate (MD) in medicine from Cambridge University, and was a Fellow of his college from 1787 to 1828. He worked as a ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colombia
Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuela to the east and northeast, Brazil to the southeast, Peru and Ecuador to the south and southwest, the Pacific Ocean to the west, and Panama to the northwest. Colombia is divided into 32 Departments of Colombia, departments. The Capital District of Bogotá is also the List of cities in Colombia by population, country's largest city hosting the main financial and cultural hub. Other major urban areas include Medellín, Cali, Barranquilla, Cartagena, Colombia, Cartagena, Santa Marta, Cúcuta, Ibagué, Villavicencio and Bucaramanga. It covers an area of 1,141,748 square kilometers (440,831 sq mi) and has a population of around 52 million. Its rich cultural heritage—including language, religion, cuisine, and art—reflects its history as a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Julius Caesar Scaliger
Julius Caesar Scaliger (; 23 April or August 1484 – 21 October 1558), or Giulio Cesare della Scala, was an Italian scholar and physician, who spent a major part of his career in France. He employed the techniques and discoveries of Renaissance humanism to defend Aristotelianism against the New Learning. In spite of his contentious disposition, his contemporary reputation was high. Jacques Auguste de Thou claimed that none of the ancients could be placed above him and that he had no equal in his own time. Biography Scaliger's father, Benedetto Bordone, was a miniaturist and illuminator. Scaliger himself was known in his youth by the family name Bordone, but later insisted that he was a scion of the house of La Scala, for a hundred and fifty years lords of Verona. He was born in Padua on 23 April or August 1484, though his son later claimed that he was born at the Rocca di Riva, on Lake Garda. There are two accounts of his life, his own and that of his critics. His own acc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pre-Columbian
In the history of the Americas, the pre-Columbian era, also known as the pre-contact era, or as the pre-Cabraline era specifically in Brazil, spans from the initial peopling of the Americas in the Upper Paleolithic to the onset of European colonization of the Americas, European colonization, which began with Christopher Columbus's voyage in 1492. This era encompasses the history of Indigenous peoples of the Americas, Indigenous cultures prior to significant European influence, which in some cases did not occur until decades or even centuries after Columbus's arrival. During the pre-Columbian era, many civilizations developed permanent settlements, cities, agricultural practices, civic and monumental architecture, major Earthworks (archaeology), earthworks, and Complex society, complex societal hierarchies. Some of these civilizations had declined by the time of the establishment of the first permanent European colonies, around the late 16th to early 17th centuries, and are know ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gadolinium
Gadolinium is a chemical element; it has Symbol (chemistry), symbol Gd and atomic number 64. It is a silvery-white metal when oxidation is removed. Gadolinium is a malleable and ductile rare-earth element. It reacts with atmospheric oxygen or moisture slowly to form a black coating. Gadolinium below its Curie point of is ferromagnetism, ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetism, paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare earths because of their similar chemical properties. Gadolinium was discovered in 1880 by Jean Charles Galissard de Marignac, Jean Charles de Marignac, who detected its oxide by using spectroscopy. It is named after the mineral gadolinite, one of the minerals in which gadolinium is found, itself named for the Finnish chemist Johan Gadolin. Pure gadolinium was first isolated by the chemis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferromagnetic
Ferromagnetism is a property of certain materials (such as iron) that results in a significant, observable magnetic permeability, and in many cases, a significant magnetic coercivity, allowing the material to form a permanent magnet. Ferromagnetic materials are noticeably attracted to a magnet, which is a consequence of their substantial magnetic permeability. Magnetic permeability describes the induced magnetization of a material due to the presence of an external magnetic field. For example, this temporary magnetization inside a steel plate accounts for the plate's attraction to a magnet. Whether or not that steel plate then acquires permanent magnetization depends on both the strength of the applied field and on the coercivity of that particular piece of steel (which varies with the steel's chemical composition and any heat treatment it may have undergone). In physics, multiple types of material magnetism have been distinguished. Ferromagnetism (along with the similar effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalt
Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, somewhat brittle, gray metal. Cobalt-based blue pigments (cobalt blue) have been used since antiquity for jewelry and paints, and to impart a distinctive blue tint to glass. The color was long thought to be due to the metal bismuth. Miners had long used the name ''kobold ore'' (German language, German for ''goblin ore'') for some of the blue pigment-producing minerals. They were so named because they were poor in known metals and gave off poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), which was ultimately named for the ''kobold''. Today, some cobalt is produced sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
