Portal:Chemistry
The Chemistry Portal
Welcome to the chemistry portal. Chemistry is a branch of science. Modern chemistry focuses on the study of elements of the world and the bonds between elements. Chemistry also deals with composition, structure, and properties of substances and the transformations that they undergo. In the study of matter, chemistry also investigates its interactions with energy and itself. Because of the diversity of matter, which is mostly in the form of compounds, chemists often study how atoms of different chemical elements interact to form molecules, and how molecules interact with each other.
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Caffeine is a xanthine alkaloid compound that acts as a stimulant in humans. Caffeine is sometimes called guaranine when found in guarana, mateine when found in mate, and theine when found in tea. It is found in the leaves and beans of the coffee plant, in tea, yerba mate, and guarana berries, and in small quantities in cocoa, the kola nut and the Yaupon Holly. Overall, caffeine is found in the beans, leaves, and fruit of over 60 plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding upon them.
Caffeine is a central nervous system (CNS) stimulant, having the effect of temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity: caffeine is the world's most widely consumed psychoactive substance. In North America, 90% of adults consume caffeine daily. Many natural sources of caffeine also contain widely varying mixtures of other xanthine alkaloids, including the cardiac stimulants theophylline and theobromine and other substances such as tannins. Selected pictureThe petroleum industry is an important supplier of chemical feedstocks. The picture shows gas storage tanks at the MiRO oil refinery in Karlsruhe, Germany. Categories
History and Philosophy of ChemistryMany chemists have an interest in the history of chemistry. Those with philosophical interests will be interested that the philosophy of chemistry has quite recently developed along a path somewhat different from the general philosophy of science. Other articles that might interest you are: There is a Wikipedia Project on the History of Science and a portal for the philosophy of science. Chemistry ResourcesWikipedia:WikiProject Chemicals/Data is a collection of links and references that are useful for chemistry-related works. This includes free online chemical databases, publications, patents, computer programs, and various tools. Science is Fun University of Wisconsin–Madison Chemistry Professor Bassam Z. Shakhashiri, shares the fun of science. megaConverter The Web's best place to figure out what equals what. General Chemistry Online Clear text and comprehensive coverage of general chemistry topics by Fred Senese, Dept. of Chemistry Frostburg State University General Chemistry Demonstration at Purdue Video clips (and descriptions) of lecture demonstrations. Intota Chemistry Experts A large online listing of real-world chemistry expert biographies provides examples of the many areas of expertise and careers in chemistry. Chemistry Webercises Directory A large listing of chemistry resources maintained by Steven Murov, Emeritus Chemistry Professor Modesto Junior College. MathMol MathMol (Mathematics and Molecules) is a good starting point for those interested in the field of molecular modeling. Chemistry Educational Resources and Essential References from Wiley, the world's largest chemistry publisher ABC-Chemistry A directory of free full-text journals in chemistry, biochemistry and related subjects. The Element Song A goofy little song about all of the elements. In the news
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Amedeo Avogadro (1776-1856) was an Italian chemist, most noted for his contributions to the theory of molarity and molecular mass. Avogadro's law implies that the relationship occurring between the weights of same volumes of different gases (at the same temperature and pressure) corresponds to the relationship between respective molecular weights. Hence, relative molecular masses can be calculated from the masses of gas samples. One of the most important contributions of Avogadro's work was clearly distinguishing atoms from molecules, admitting that simple particles too could be composed of molecules, and that these are composed of atoms.
Techniques used by chemistsEquipment used by chemistsChemistry in societyChemistry in industryCompanies: AstraZeneca - Bayer - BP - BASF - Bristol Myers Squibb - Degussa - Dow - DuPont - ExxonMobil - GlaxoSmithKline - The Linde Group - Mitsubishi - Monsanto - Nestlé - OSI - Shell - Sigma-Aldrich - Total WikiProjectsPeriodic Table
This common arrangement of the periodic table separates the lanthanides (lanthanoids) and actinides (actinoids) (the f-block) from other elements. The wide periodic table incorporates the f-block. The extended periodic table adds the 8th and 9th periods, incorporating the f-block and adding the theoretical g-block.
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