Portal:Chemistry
The Chemistry Portal Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances. Chemistry also addresses the nature of chemical bonds in chemical compounds. In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant growth (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the Moon (cosmochemistry), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics). Chemistry has existed under various names since ancient times. It has evolved, and now chemistry encompasses various areas of specialisation, or subdisciplines, that continue to increase in number and interrelate to create further interdisciplinary fields of study. The applications of various fields of chemistry are used frequently for economic purposes in the chemical industry. (Full article...) Portal navigation
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The binding of an inhibitor can stop a substrate from entering the enzyme's active site and/or hinder the enzyme from catalysing its reaction. Inhibitor binding is either reversible or irreversible. Irreversible inhibitors usually react with the enzyme and change it chemically. These inhibitors modify key amino acid residues needed for enzymatic activity. In contrast, reversible inhibitors bind non-covalently and different types of inhibition are produced depending on whether these inhibitors bind the enzyme, the enzyme-substrate complex, or both. Many drug molecules are enzyme inhibitors so their discovery and improvement is an active area of research in biochemistry and pharmacology. A medicinal enzyme inhibitor is often judged by its specificity (its lack of binding to other proteins) and its potency (its dissociation constant, which indicates the concentration needed to inhibit the enzyme). A high specificity and potency ensure that a drug will have few side effects and thus low toxicity. Enzyme inhibitors also occur naturally and are involved in the regulation of metabolism. For example, enzymes in a metabolic pathway can be inhibited by downstream products. This type of negative feedback slows flux through a pathway when the products begin to build up and is an important way to maintain homeostasis in a cell. Other cellular enzyme inhibitors are proteins that specifically bind to and inhibit an enzyme target. This can help control enzymes that may be damaging to a cell, such as proteases or nucleases; a well-characterised example is the ribonuclease inhibitor, which binds to ribonucleases in one of the tightest known protein–protein interactions. Natural enzyme inhibitors can also be poisons and are used as defences against predators or as ways of killing prey. Selected picture Malachite is a carbonate mineral, copper(II) carbonate hydroxide Cu2CO3(OH)2. It crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Its beauty may be seen most strikingly in the Malachite Room at the Hermitage in Saint Petersburg.
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History and Philosophy of Chemistry Many 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. Chemistry Resources Wikipedia: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. unit-conversion.info A good 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. 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. 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
Selected biographyYuan Tseh Lee (born 1936) is a Taiwanese chemist, and the first Taiwanese-born Nobel Prize laureate. Along with John Charles Polanyi and Dudley R. Herschbach, he received the 1986 Nobel Prize in Chemistry "for their contributions to the dynamics of chemical elementary processes." Lee's particular work was on crossed molecular beams, to further its use in general reactions, a method for the study of important reactions for relatively large molecules. Since 1994, Lee has been the President of the Academia Sinica of the Republic of China. Techniques used by chemists Equipment used by chemists Aspirator - Beaker - Boiling tube - Büchner funnel - Bunsen burner - Burette - Calorimeter - Colorimeter - Conical measure - Nuclear Magnetic Resonance - Mass Spectrometer - Liquid Chromatography - Gas Chromatography - Crucible - Cuvette - Laboratory flasks (Büchner, Erlenmeyer, Florence, Retort, Round-bottom, Volumetric) - Fume hood - Gas syringe - Graduated cylinder - Perkin triangle - Pipette - Reagent - Separating funnel - Spectrophotometer - Schlenk flask - pH indicator - Litmus papers - Tongs - Soxhlet extractor - Stir bar - Static mixer - Test tube - Thistle tube - Viscometer
Chemistry in society Acid rain - Air pollution - Anabolic steroids - Asbestos - Aspartame - Aspirin - CFCs - Cholesterol - Carbohydrates - Carbon dioxide - Chemical warfare - Enzymes - Fat - Fatty acid - Free radicals - Fuel cell - Gasoline - Green chemistry - Hormonal contraception - Insulin - Nuclear fuel - Nuclear fusion - Nylon - Ozone - Paracetamol - Penicillin - Plastic - Psychoactive drugs - Radioactive waste - Smog - Soil contamination - Sugar - Tamiflu - Viagra - Vitamins
Chemistry in industry Types of chemical industry: Agrochemicals - Chemical industry - Organometallic chemistry - Oleochemicals - Paints - Petrochemicals - Pharmaceuticals - Polymers
Companies: AstraZeneca - Bayer - BP - BASF - Bristol-Myers Squibb - DowDuPont - Evonik Industries - ExxonMobil - Linde plc - Mitsubishi - Monsanto - Nestlé - OSI - Shell - Sigma-Aldrich - Sasol - Total - GlaxoSmithKline - Teva WikiProjectsPeriodic Table
Standard atomic weight Ar, std(E)[1]
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- ^ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–291. doi:10.1515/pac-2015-0305.
- ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.