1.
Wernigerode
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Wernigerode is a town in the district of Harz, Saxony-Anhalt, Germany. Until 2007, it was the capital of the district of Wernigerode and its population was 35,041 in 2012. Wernigerode is located southwest of Halberstadt, and is situated on the Holtemme river. Wernigerode is located on the German Timber-Frame Road, the River Holtemme flows through the town and, not far from its western gate, it is joined by the Zillierbach stream, which is also known as the Flutrenne near its mouth. North of the town the Barrenbach flows through several ponds and empties into the Holtemme in the village of Minsleben, the historic town centre consists of an old town and a new town. The towns borough includes Hasserode, Nöschenrode, the estates of Stadtfeld, Burgbreite and Harzblick as well as the villages of Benzingerode, Minsleben, Silstedt, Schierke. The borough measures 9.5 km from west to east and 6 km from north to south and its highest point is the Brocken, at 1,141 metres above NN, and its lowest is at 215 metres. The town lies on the German-Dutch holiday road known as the Orange Route, the Northern Harz Boundary Fault crosses the borough along which runs the watershed between the Weser and Elbe rivers. To the north flows into the Weser, to the southeast, later northeast. This fault line runs through the suburb of Hasserode to the west south west of the city centre, Wernigerode is located in the Central European transition subzone of the temperate climatic zone. Its average annual temperature is 9.5 °C, its annual precipitation is 500 millimetres. The warmest months are June to August with average temperatures of 16.0 to 18.3 °C, the most rain falls in July, on average 54 millimetres, the least in February, with 30 millimetres on average. The climate, more precisely the amounts of precipitation and temperatures, are influenced by the rainfall caused by the Harz Mountains. Because the town lies in the shadow of the Harz. In addition the occasional föhn winds that result in an increase in temperatures. Wernigerode has a snow load class of 3 according to the German industrial standard, Wernigerode was the capital of the medieval County of Wernigerode and Stolberg-Wernigerode. In 1815, after the Napoleonic Wars, it part of the Prussian Province of Saxony. The Hasseröder brewery was founded in Wernigerode in 1872, after World War II, Wernigerode was included in the new state Saxony-Anhalt within the Soviet occupation zone
2.
Berlin
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Berlin is the capital and the largest city of Germany as well as one of its constituent 16 states. With a population of approximately 3.5 million, Berlin is the second most populous city proper, due to its location in the European Plain, Berlin is influenced by a temperate seasonal climate. Around one-third of the area is composed of forests, parks, gardens, rivers. Berlin in the 1920s was the third largest municipality in the world, following German reunification in 1990, Berlin once again became the capital of all-Germany. Berlin is a city of culture, politics, media. Its economy is based on high-tech firms and the sector, encompassing a diverse range of creative industries, research facilities, media corporations. Berlin serves as a hub for air and rail traffic and has a highly complex public transportation network. The metropolis is a popular tourist destination, significant industries also include IT, pharmaceuticals, biomedical engineering, clean tech, biotechnology, construction and electronics. Modern Berlin is home to world renowned universities, orchestras, museums and its urban setting has made it a sought-after location for international film productions. The city is known for its festivals, diverse architecture, nightlife, contemporary arts. Since 2000 Berlin has seen the emergence of a cosmopolitan entrepreneurial scene, the name Berlin has its roots in the language of West Slavic inhabitants of the area of todays Berlin, and may be related to the Old Polabian stem berl-/birl-. All German place names ending on -ow, -itz and -in, since the Ber- at the beginning sounds like the German word Bär, a bear appears in the coat of arms of the city. It is therefore a canting arm, the first written records of towns in the area of present-day Berlin date from the late 12th century. Spandau is first mentioned in 1197 and Köpenick in 1209, although these areas did not join Berlin until 1920, the central part of Berlin can be traced back to two towns. Cölln on the Fischerinsel is first mentioned in a 1237 document,1237 is considered the founding date of the city. The two towns over time formed close economic and social ties, and profited from the right on the two important trade routes Via Imperii and from Bruges to Novgorod. In 1307, they formed an alliance with a common external policy, in 1415 Frederick I became the elector of the Margraviate of Brandenburg, which he ruled until 1440. In 1443 Frederick II Irontooth started the construction of a new palace in the twin city Berlin-Cölln
3.
Chemistry
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Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is sometimes called the science because it bridges other natural sciences, including physics. For the differences between chemistry and physics see comparison of chemistry and physics, the history of chemistry can be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from alchemy, which referred to a set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism. An alchemist was called a chemist in popular speech, and later the suffix -ry was added to this to describe the art of the chemist as chemistry, the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία and this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. Alternately, al-kīmīā may derive from χημεία, meaning cast together, in retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term chymistry, in the view of noted scientist Robert Boyle in 1661, in 1837, Jean-Baptiste Dumas considered the word chemistry to refer to the science concerned with the laws and effects of molecular forces. More recently, in 1998, Professor Raymond Chang broadened the definition of chemistry to mean the study of matter, early civilizations, such as the Egyptians Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didnt develop a systematic theory. Greek atomism dates back to 440 BC, arising in works by such as Democritus and Epicurus. In 50 BC, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura, unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. He formulated Boyles law, rejected the four elements and proposed a mechanistic alternative of atoms. Before his work, though, many important discoveries had been made, the Scottish chemist Joseph Black and the Dutchman J. B. English scientist John Dalton proposed the theory of atoms, that all substances are composed of indivisible atoms of matter. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current, british William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhlers synthesis of urea which proved that organisms were, in theory
4.
Chemist
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A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties, chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, reaction rates, and other chemical properties, the word chemist is also used to address Pharmacists in Commonwealth English. Chemists may specialize in any number of subdisciplines of chemistry, materials scientists and metallurgists share much of the same education and skills with chemists. The roots of chemistry can be traced to the phenomenon of burning, fire was a mystical force that transformed one substance into another and thus was of primary interest to mankind. It was fire that led to the discovery of iron and glasses, after gold was discovered and became a precious metal, many people were interested to find a method that could convert other substances into gold. This led to the protoscience called alchemy, the word chemist is derived from the New Latin noun chimista, an abbreviation of alchimista. Alchemists discovered many chemical processes that led to the development of modern chemistry, Chemistry as we know it today, was invented by Antoine Lavoisier with his law of conservation of mass in 1783. The discoveries of the elements has a long history culminating in the creation of the periodic table by Dmitri Mendeleev. The Nobel Prize in Chemistry created in 1901 gives an excellent overview of chemical discovery since the start of the 20th century. Jobs for chemists usually require at least a degree, but many positions, especially those in research. At the Masters level and higher, students tend to specialize in a particular field, postdoctoral experience may be required for certain positions. Workers whose work involves chemistry, but not at a complexity requiring an education with a degree, are commonly referred to as chemical technicians. Such technicians commonly do such work as simpler, routine analyses for quality control or in clinical laboratories, there are also degrees specific to become a Chemical Technologist, which are somewhat distinct from those required when a student is interested in becoming a professional Chemist. A Chemical technologist is more involved in the management and operation of the equipment and they are part of the team of a chemical laboratory in which the quality of the raw material, intermediate products and finished products is analyzed. They also perform functions in the areas of quality control. The higher the level achieved in the field of Chemistry, the higher the responsibility given to that chemist. Chemistry, as a field, have so many applications that different tasks/objectives can be given to workers/scientists with these different levels of education and/or experience
5.
Uranium
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Uranium is a chemical element with symbol U and atomic number 92. It is a metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons, Uranium is weakly radioactive because all its isotopes are unstable. The most common isotopes in natural uranium are uranium-238 and uranium-235, Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and it occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238, uranium-235, Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years, many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the naturally occurring fissile isotope, which makes it widely used in nuclear power plants. However, because of the amounts found in nature, uranium needs to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor, another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. In sufficient concentration, these maintain a sustained nuclear chain reaction. This generates the heat in nuclear reactors, and produces the fissile material for nuclear weapons. Depleted uranium is used in kinetic energy penetrators and armor plating, Uranium is used as a colorant in uranium glass, producing lemon yellow to green colors. Uranium glass fluoresces green in ultraviolet light and it was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of weapons that used uranium metal. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is a concern for public health. When refined, uranium is a white, weakly radioactive metal
6.
Cerium
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Cerium is a soft, ductile, silvery-white metallic chemical element with symbol Ce and atomic number 58. Cerium tarnishes when exposed to air, and it is enough to be cut with a knife. Cerium is the element in the lanthanide series, and while it often shows the +3 state characteristic of the series. It is also considered to be one of the rare earth elements. Cerium has no role, and is not very toxic. It is the most common of the lanthanides, followed by neodymium, lanthanum and it is the 26th most abundant element, making up 66 ppm of the Earths crust, half as much as chlorine and five times as much as lead. The first of the lanthanides to be discovered, cerium was discovered in Bastnäs, Sweden by Jöns Jakob Berzelius and Wilhelm Hisinger in 1803 and it was first isolated by Carl Gustaf Mosander in 1839. Today, cerium and its compounds have a variety of uses, for example, cerium metal is used in ferrocerium lighters for its pyrophoric properties. Cerium is the element of the lanthanide series. In the periodic table, it appears between the lanthanides lanthanum to its left and praseodymium to its right, and above the actinide thorium and it is a ductile metal with a hardness similar to that of silver. Its 58 electrons are arranged in the configuration 4f15d16s2, of which the four electrons are valence electrons. The stable form below 726 °C to approximately room temperature is γ-cerium, the dhcp form of β-cerium is the equilibrium structure approximately from room temperature to −150 °C. The fcc α-cerium exists below about −150 °C, it has a density of 8.16 g/cm3, other solid phases occurring only at high pressures are shown on the phase diagram. Both γ and β forms are stable at room temperature. Cerium has an electronic structure. This gives rise to dual valency states, for example, a volume change of about 10% occurs when cerium is subjected to high pressures or low temperatures. It appears that the changes from about 3 to 4 when it is cooled or compressed. At lower temperatures the behavior of cerium is complicated by the rates of transformation
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Klaproth, Martin Heinrich". Encyclopædia Britannica. 15 (11th ed.). Cambridge University Press. pp. 844–845.
