Stromeyerite is a sulfide mineral of copper and silver, with the chemical formula AgCuS. It forms opaque blue grey to dark blue orthorhombic crystals, it was discovered in 1832 in Central Bohemia Region, Czech Republic, named after the German chemist, Friedrich Stromeyer who performed the first analysis of the mineral. List of minerals List of minerals named after people
Cadmium is a chemical element with symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are not considered transition metals, in that they do not have filled d or f electron shells in the elemental or common oxidation states; the average concentration of cadmium in Earth's crust is between 0.5 parts per million. It was discovered in 1817 by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium is a byproduct of zinc production. Cadmium was used for a long time as a corrosion-resistant plating on steel, cadmium compounds are used as red and yellow pigments, to color glass, to stabilize plastic. Cadmium use is decreasing because it is toxic and nickel-cadmium batteries have been replaced with nickel-metal hydride and lithium-ion batteries.
One of its few new uses is cadmium telluride solar panels. Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms. Cadmium is a soft, ductile, bluish-white divalent metal, it forms complex compounds. Unlike most other metals, cadmium is resistant to corrosion and is used as a protective plate on other metals; as a bulk metal, cadmium is not flammable. Although cadmium has an oxidation state of +2, it exists in the +1 state. Cadmium and its congeners are not always considered transition metals, in that they do not have filled d or f electron shells in the elemental or common oxidation states. Cadmium burns in air to form brown amorphous cadmium oxide. Hydrochloric acid, sulfuric acid, nitric acid dissolve cadmium by forming cadmium chloride, cadmium sulfate, or cadmium nitrate; the oxidation state +1 can be produced by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd22+ cation, similar to the Hg22+ cation in mercury chloride.
Cd + CdCl2 + 2 AlCl3 → Cd22The structures of many cadmium complexes with nucleobases, amino acids, vitamins have been determined. Occurring cadmium is composed of 8 isotopes. Two of them are radioactive, three are expected to decay but have not done so under laboratory conditions; the two natural radioactive isotopes are 116Cd. The other three are 106Cd, 108Cd, 114Cd. At least three isotopes – 110Cd, 111Cd, 112Cd – are stable. Among the isotopes that do not occur the most long-lived are 109Cd with a half-life of 462.6 days, 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives of less than 2.5 hours, the majority have half-lives of less than 5 minutes. Cadmium has 8 known meta states, with the most stable being 113mCd, 115mCd, 117mCd; the known isotopes of cadmium range in atomic mass from 94.950 u to 131.946 u. For isotopes lighter than 112 u, the primary decay mode is electron capture and the dominant decay product is element 47. Heavier isotopes decay through beta emission producing element 49.
One isotope of cadmium, 113Cd, absorbs neutrons with high selectivity: With high probability, neutrons with energy below the cadmium cut-off will be absorbed. The cadmium cut-off is about 0.5 eV, neutrons below that level are deemed slow neutrons, distinct from intermediate and fast neutrons. Cadmium is created via the s-process in low- to medium-mass stars with masses of 0.6 to 10 solar masses, over thousands of years. In that process, a silver atom captures a neutron and undergoes beta decay. Cadmium was discovered in 1817 by Friedrich Stromeyer and Karl Samuel Leberecht Hermann, both in Germany, as an impurity in zinc carbonate. Stromeyer found the new element as an impurity in zinc carbonate, for 100 years, Germany remained the only important producer of the metal; the metal was named after the Latin word for calamine. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not, he was persistent in studying these results and isolated cadmium metal by roasting and reducing the sulfide.
The potential for cadmium yellow as pigment was recognized in the 1840s, but the lack of cadmium limited this application. Though cadmium and its compounds are toxic in certain forms and concentrations, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands, chilblains". In 1907, the International Astronomical Union defined the international ångström in terms of a red cadmium spectral line. This
Germany the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, the Alps to the south. It borders Denmark to the north and the Czech Republic to the east and Switzerland to the south, France to the southwest, Luxembourg and the Netherlands to the west. Germany includes 16 constituent states, covers an area of 357,386 square kilometres, has a temperate seasonal climate. With 83 million inhabitants, it is the second most populous state of Europe after Russia, the most populous state lying in Europe, as well as the most populous member state of the European Union. Germany is a decentralized country, its capital and largest metropolis is Berlin, while Frankfurt serves as its financial capital and has the country's busiest airport. Germany's largest urban area is the Ruhr, with its main centres of Essen; the country's other major cities are Hamburg, Cologne, Stuttgart, Düsseldorf, Dresden, Bremen and Nuremberg. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity.
A region named Germania was documented before 100 AD. During the Migration Period, the Germanic tribes expanded southward. Beginning in the 10th century, German territories formed a central part of the Holy Roman Empire. During the 16th century, northern German regions became the centre of the Protestant Reformation. After the collapse of the Holy Roman Empire, the German Confederation was formed in 1815; the German revolutions of 1848–49 resulted in the Frankfurt Parliament establishing major democratic rights. In 1871, Germany became a nation state when most of the German states unified into the Prussian-dominated German Empire. After World War I and the revolution of 1918–19, the Empire was replaced by the parliamentary Weimar Republic; the Nazi seizure of power in 1933 led to the establishment of a dictatorship, the annexation of Austria, World War II, the Holocaust. After the end of World War II in Europe and a period of Allied occupation, Austria was re-established as an independent country and two new German states were founded: West Germany, formed from the American and French occupation zones, East Germany, formed from the Soviet occupation zone.
Following the Revolutions of 1989 that ended communist rule in Central and Eastern Europe, the country was reunified on 3 October 1990. Today, the sovereign state of Germany is a federal parliamentary republic led by a chancellor, it is a great power with a strong economy. As a global leader in several industrial and technological sectors, it is both the world's third-largest exporter and importer of goods; as a developed country with a high standard of living, it upholds a social security and universal health care system, environmental protection, a tuition-free university education. The Federal Republic of Germany was a founding member of the European Economic Community in 1957 and the European Union in 1993, it is part of the Schengen Area and became a co-founder of the Eurozone in 1999. Germany is a member of the United Nations, NATO, the G7, the G20, the OECD. Known for its rich cultural history, Germany has been continuously the home of influential and successful artists, musicians, film people, entrepreneurs, scientists and inventors.
Germany has a large number of World Heritage sites and is among the top tourism destinations in the world. The English word Germany derives from the Latin Germania, which came into use after Julius Caesar adopted it for the peoples east of the Rhine; the German term Deutschland diutisciu land is derived from deutsch, descended from Old High German diutisc "popular" used to distinguish the language of the common people from Latin and its Romance descendants. This in turn descends from Proto-Germanic *þiudiskaz "popular", derived from *þeudō, descended from Proto-Indo-European *tewtéh₂- "people", from which the word Teutons originates; the discovery of the Mauer 1 mandible shows that ancient humans were present in Germany at least 600,000 years ago. The oldest complete hunting weapons found anywhere in the world were discovered in a coal mine in Schöningen between 1994 and 1998 where eight 380,000-year-old wooden javelins of 1.82 to 2.25 m length were unearthed. The Neander Valley was the location where the first non-modern human fossil was discovered.
The Neanderthal 1 fossils are known to be 40,000 years old. Evidence of modern humans dated, has been found in caves in the Swabian Jura near Ulm; the finds included 42,000-year-old bird bone and mammoth ivory flutes which are the oldest musical instruments found, the 40,000-year-old Ice Age Lion Man, the oldest uncontested figurative art discovered, the 35,000-year-old Venus of Hohle Fels, the oldest uncontested human figurative art discovered. The Nebra sky disk is a bronze artefact created during the European Bronze Age attributed to a site near Nebra, Saxony-Anhalt, it is part of UNESCO's Memory of the World Programme. The Germanic tribes are thought to date from the Pre-Roman Iron Age. From southern Scandinavia and north Germany, they expanded south and west from the 1st century BC, coming into contact with the Celtic tribes of Gaul as well
Eilhard Mitscherlich was a German chemist, best remembered today for his discovery of the phenomenon of isomorphism in 1819. Mitscherlich was born at Neuende in the Lordship of Jever, his uncle, Christoph Wilhelm Mitscherlich, professor at the University of Göttingen, was in his day a celebrated scholar. Eilhard Mitscherlich was educated at Jever by the historian Friedrich Christoph Schlosser, in 1811 went to the University of Heidelberg devoting himself to philology, with an emphasis on the Persian language. In 1813 he went to Paris to seek permission to join the embassy which Napoleon I of France was establishing in Persia; the abdication of Napoleon Bonaparte in 1814 put an end to this, Mitscherlich resolved to study medicine in order that he might enjoy that freedom of travel allowed in the East to physicians. He began at Göttingen with the study of chemistry, this so arrested his attention that he gave up his idea to travel to Persia. From his days in Göttingen dates the treatise on certain parts of Eurasian history, compiled from manuscripts found in the university library and published in Persian and Latin in 1814, under the title Mirchondi historia Thaheridarum historicis nostris hucusque incognitorum Persiae principum.
In 1818 Mitscherlich worked in the laboratory of Heinrich Friedrich Link. There he studied phosphates, phosphites and arsenites, was able to confirm the conclusions of Jöns Jakob Berzelius as to their composition, his observation that corresponding phosphates and arsenates crystallize in the same form was the germ from which grew his theory of isomorphism, which theory was published in the proceedings of the Berlin Academy of Sciences in December 1819. In that same year Berzelius suggested Mitscherlich to the Prussian education minister Karl vom Stein zum Altenstein as successor to Martin Heinrich Klaproth at the University of Berlin. Altenstein did not carry out this suggestion, but he obtained for Mitscherlich a government grant to enable him to continue his studies in Berzelius' laboratory at the Karolinska Institutet in Stockholm. Mitscherlich returned to Berlin in 1821, in the summer of 1822 he delivered his first lecture as extraordinary professor of chemistry at the university. In 1823 Mitscherlich was elected as foreign member of the Royal Swedish Academy of Sciences.
In the course of investigating the slight differences discovered by William Hyde Wollaston in the angles of the rhombohedra of the carbonates isomorphous with calcite, Mitscherlich observed that this angle in the case of calcite varied with the temperature. On extending this inquiry to other allotropic crystals, he observed a similar variation, was thus led, in 1825, to the discovery that allotropic crystals, when heated, expand unequally in the direction of dissimilar axes. In the following year he discovered the change, produced by change of temperature, in the direction of the optic axes of selenite, his investigation in 1826, of the two crystalline modifications of sulfur threw much light on the fact that the two minerals calcite and aragonite have the same composition but different crystalline forms, a property which Mitscherlich called polymorphism. In 1833 Mitscherlich made a series of careful determinations of the vapor densities of a large number of volatile substances, confirming the law of Gay-Lussac.
In 1833-34, Mitscherlich investigated the synthesis of diethyl ether from sulfuric acid. Through his careful studies, he realized that the acid was not being consumed during the production of the ether, although the reaction would not proceed unless the acid was present. After reviewing Mitscherlich's findings, Swedish chemist Jöns Jacob Berzelius was led to coin the term "catalysis" for the acceleration or enablement of a chemical reaction by a substance that itself was not consumed in the reaction, he obtained selenic acid in 1827 and showed that its salts are isomorphous with the sulphates, while a few years he proved that the same thing is true of the manganates and the sulfates, of the permanganates and the perchlorates. He investigated the relation of benzene to other derivatives; as related by Gustav Rose Mitscherlich turned away from inorganic chemistry and devoted his attention to organic chemistry, starting out with an investigation of fuel and oil. Mitscherlich kept working on problems of organic chemistry until 1845.
His interest in mineralogy led him to study the geology of volcanic regions, he made frequent visits to the Eifel in an attempt to develop a theory on the cause of volcanism. He did not, publish any papers on the subject, though after his death his notes were arranged and published by J. L. A. Roth in the Memoirs of the Berlin Academy. Mitscherlich was an honorary member of all the great scientific societies, received the gold medal from the Royal Society of London for his discovery of the law of isomorphism, he was one of the few foreign associates of the French Institute. In 1855, Mitscherlichwas elected a Foreign Honorary Member of the American Academy of Arts and Sciences. In December 1861, symptoms of heart disease made their appearance, but Mitscherlich was able to carry on his academic work until December 1862, he died at Schöneberg near Berlin in 1863 and was buried in the St Matthäus Kirchhof Cemetery in Schöneberg close to the gravesites of Gustav Kirchhoff and Leopold Kronecker. Mitscherlich pu
Robert Wilhelm Eberhard Bunsen was a German chemist. He investigated emission spectra of heated elements, discovered caesium and rubidium with the physicist Gustav Kirchhoff. Bunsen developed several gas-analytical methods, was a pioneer in photochemistry, did early work in the field of organoarsenic chemistry. With his laboratory assistant, Peter Desaga, he developed the Bunsen burner, an improvement on the laboratory burners in use; the Bunsen–Kirchhoff Award for spectroscopy is named after Bunsen and Kirchhoff. Robert Bunsen was born at Göttingen in what is now the state of Lower Saxony in Germany. Bunsen was the youngest of four sons of the University of Göttingen's chief librarian and professor of modern philology, Christian Bunsen. After attending school in Holzminden, Bunsen matriculated at Göttingen in 1828 and studied chemistry with Friedrich Stromeyer as well as mineralogy with Johann Friedrich Ludwig Hausmann and mathematics with Carl Friedrich Gauss. After obtaining a PhD in 1831, Bunsen spent 1832 and 1833 traveling in Germany and Austria.
In 1833 Bunsen became a lecturer at Göttingen and began experimental studies of the solubility of metal salts of arsenous acid. His discovery of the use of iron oxide hydrate as a precipitating agent is still today the most effective antidote against arsenic poisoning; this interdisciplinary research was carried on and published in conjunction with the physician Arnold Adolph Berthold. In 1836, Bunsen succeeded Friedrich Wöhler at the Polytechnic School of Kassel. Bunsen taught there for three years, accepted an associate professorship at the University of Marburg, where he continued his studies on cacodyl derivatives, he was promoted to full professorship in 1841. While at University of Marburg, Bunsen participated in the 1846 expedition for the investigation of Iceland's volcanoes. Bunsen's work brought him quick and wide acclaim because cacodyl, toxic and undergoes spontaneous combustion in dry air, is so difficult to work with. Bunsen died from arsenic poisoning, an explosion with cacodyl cost him sight in his right eye.
In 1841, Bunsen created the Bunsen cell battery, using a carbon electrode instead of the expensive platinum electrode used in William Robert Grove's electrochemical cell. Early in 1851 he accepted a professorship at the University of Breslau, where he taught for three semesters. In late 1852 Bunsen became the successor of Leopold Gmelin at the University of Heidelberg. There he used electrolysis to produce pure metals, such as chromium, aluminum, sodium, barium and lithium. A long collaboration with Henry Enfield Roscoe began in 1852, in which they studied the photochemical formation of hydrogen chloride from hydrogen and chlorine. From this work, the reciprocity law of Bunsen and Roscoe originated, he discontinued his work with Roscoe in 1859 and joined Gustav Kirchhoff to study emission spectra of heated elements, a research area called spectrum analysis. For this work and his laboratory assistant, Peter Desaga, had perfected a special gas burner by 1855, influenced by earlier models; the newer design of Bunsen and Desaga, which provided a hot and clean flame, is now called the "Bunsen burner", a common laboratory equipment.
There had been earlier studies of the characteristic colors of heated elements, but nothing systematic. In the summer of 1859, Kirchhoff suggested to Bunsen that he should try to form prismatic spectra of these colors. By October of that year the two scientists had invented an appropriate instrument, a prototype spectroscope. Using it, they were able to identify the characteristic spectra of sodium and potassium. After numerous laborious purifications, Bunsen proved that pure samples gave unique spectra. In the course of this work, Bunsen detected unknown new blue spectral emission lines in samples of mineral water from Dürkheim, he guessed. After careful distillation of forty tons of this water, in the spring of 1860 he was able to isolate 17 grams of a new element, he named the element "caesium", after the Latin word for deep blue. The following year he discovered rubidium, by a similar process. In 1860, Bunsen was elected a foreign member of the Royal Swedish Academy of Sciences. In 1877, Robert Bunsen together with Gustav Robert Kirchhoff were the first recipients of the prestigious Davy Medal "for their researches & discoveries in spectrum analysis".
Bunsen was one of the most universally admired scientists of his generation. He was a master teacher, devoted to his students, they were devoted to him. At a time of vigorous and caustic scientific debates, Bunsen always conducted himself as a perfect gentleman, maintaining his distance from theoretical disputes, he much preferred to work in his laboratory, continuing to enrich his science with useful discoveries. As a matter of principle he never took out a patent, he never married. Despite his lack of pretension, Bunsen was a vivid "chemical character," had a well-developed sense of humor, is the subject of many amusing anecdotes; when Bunsen retired at the age of 78, he shifted his work to geology and mineralogy, interests which he had pursued throughout his career. He died in Heidelberg at the age of 88. Bunsen reaction Bunsenite Pneumatolysis List of German inventors and discoverers Media related to Robert Bunsen at Wikimedia Commons Robert Wilhelm Bunse