Applications 1
Applications for superconducting materials include strong superconducting magnets without iron cores, which in turn have a variety of uses. These superconducting magnets are used in particle accelerators, nuclear magnetic resonance and magnetic circular dichroism instruments, magnetic resonance imaging devices in medicine, levitating trains, magnetic refrigerators, magnetic energy storage, and SQUIDS superconducting quantum interference devices for very sensitive magnetic field measurements...
AcidBase Neutralization Reactions
A neutralization reaction is a double-displacement reaction of an acid and a base. Acids are compounds that can release hydrogen ions bases are compounds that can neutralize acids by reacting with hydrogen ions. The most common bases are hydroxide and oxide compounds of the metals. Normally, an acid reacts with a base to form a salt and water. Neutralization reactions occur because of the formation of the very stable covalent water molecule, H2O, from hydrogen and hydroxide ions. HCl aq NaOH aq...
Other Synthetic Rubbers
In 1937 Robert McKee Thomas 1908-1986 and William Joseph Sparks 1904-1976 at the Standard Oil Development Company now Exxon synthesized butyl rubber via the copolymerization polymerization of a mixture of monomers of isobutylene 2-methylpropene CH3 2C CH2 with a small amount of isoprene. By 1929 the German firm I. G. Farben developed a series of synthetic rubbers similar to those produced in the USSR. They were called Buna rubbers Bu for butadiene, one of the copolymers, and na for sodium, the...
D
Dacron, 2 93, 94 Daguerre, Louis-Jacques-Mand , 3 249 Daguerreotype, 3 249 Dalton, John, 2 1-3, 2 921, 114, 2 2, 3 114, 4 252 Avogadro's theory and, 1 99-100 Gay-Lussac's research and, 2 149-150 law of definite proportions and, 4 171, 172 Damascus Steel, 4 163 Dana's Manual of Minerology, 3 91 Dangling bonds, 2 128 Daniell cells, 2 35-36, 37 Data falsification, 2 68-69, 70 Data storage, 3 127 Dating, carbon radiometric , 3 169-170, 4 55 Davis, Arthur Vining, 2 191-192 Davisson, Charles J., 2 5...
Surface Tension
Surface tension is the appearance of a film over the top of a liquid, making the liquid behave as if it had a skin. It is because of surface tension that a small object like a pin or an insect can be supported on the surface of a liquid. This phenomenon is caused by the attraction between molecules of a liquid. In the bulk of a liquid any individual molecule is attracted equally in all directions by all adjacent molecules. At the surface of the liquid, however, there are no molecules attracting...
Conclusion Kwm
As long as society continues to puts great emphasis on looking young and beautiful cosmetic chemistry will continue to flourish. A good understanding of the fundamentals of emulsion chemistry and skin physiology are prerequisites, when formulating personal care products. A good cosmetic chemist must be able to combine science and art to create products with the feel and look that consumers desire. Harry, Ralph G. 2000 . Harry's Cosmeticology, 8th edition, ed. Martin M. Reiger. Chemical...
Two Serendipitous Discoveries
During World War II the United States, cut off from India, Ceylon now Sri Lanka , Malaysia, and the Dutch East Indies areas which, since the late nineteenth century, had replaced South America as the main suppliers of natural rubber , developed several superior synthetic rubbers. The U.S. synthetic rubber industry originated from two discoveries that were serendipitous that is, they occurred while the researchers were searching for something else. In 1922 independent inventor and physician...
Names in Coordination Nomenclature
The names of coordination entities are assembled using principles similar, but not identical, to those used for formulae. The central atom is always cited last. Its name may be modified by an oxidation state symbol. The lig-ands are presented in the alphabetical order of their initial letters, neglecting for this purpose any multiplicative prefixes. It is not necessary to divide the ligands into neutral and charged groups. However, the names of negatively charged ligands are generally modified...
Mendelevium
MELTING POINT 827 C BOILING POINT Unknown DENSITY Unknown MOST COMMON IONS Md2 , Md3 Mendelevium was discovered in 1955 by Albert Ghiorso, Bernard G. Harvey, Gregory R. Choppin, Stanley G. Thompson, and Glenn T. Seaborg via the bombardments of a minute quantity of a rare, radioactive isotope of einsteinium 253Es with a-particles in the 60-inch cyclotron of the University of California, Berkeley, which produced 256Md. Only 17 atoms were detected. Md is the first element to be produced and...
Avogadro Amedeo
atomic theory physical concept that asserts that matter is composed of microscopically tiny particles called atoms and that various elements differ from each other by having different atoms In 1811, just three years after John Dalton published his atomic theory, a brilliant theoretician named Amedeo Avogadro proposed his molecular theory. Avogadro's molecular theory related gas densities to molecular weights, explained reacting proportions by volume in terms of molecular ratios and...
Epinephrine
adrenalin chemical secreted in the body in response to stress glucose common hexose monosaccharide monomer of starch and cellulose also called grape sugar, blood sugar, or dextrose tyrosine one of the common amino acids intermediate molecule, often short-lived, that occurs while a chemical reaction progresses but is not present when the reaction is complete receptor area on or near a cell wall that accepts another molecule to allow a change in the cell synthesis combination of starting...
Waksman Selman Abraham
Selman Waksman changed the course of medical history while investigating how soil microbes defended themselves against invaders. He and coworkers isolated twenty-two new defensive compounds produced by soil microbes streptomycin antibiotic produced by soil and in the process discovered streptomycin, the first antibiotic effective bacteria of genus Streptomyces against tuberculosis. For his discovery of streptomycin, Waksman received the 1952 Nobel Prize in physiology or medicine. Selman Abraham...
Coordination Compounds
Transition metals readily react with halogens to form binary compounds of various colors, for example green-black ferric chloride FeCl3 , deep blue cobalt chloride CoCl2 , and golden yellow nickel bromide NiBr2 . These compounds dissolve in water to give brightly colored solutions but of changed colors yellow solutions containing Fe3 ions , red solutions Co2 ions , and green solutions Ni2 ions . By evaporating the solutions, crystals of these new compounds can be obtained yellow FeCl3 6H2O, red...
Overall Reaction Order
When the sucrose inversion reaction was later run in nonaqueous solvents it was recognized that a better description of the rate of disappearance of sucrose S is given by the following equations SH H2O -d glucose fructose H -d S dt k SH H2O kKc S H H2O Thus, the reaction rate is first-order in sucrose, first-order in the catalyst catalyst substance that aids in a reaction H , and first-order in H2O. The reaction is said to be third-order overall, while retaining its own chemical identity third...
Yukawa Hideki
Hideki Ogawa he changed his surname upon marrying Sumi Yukawa was born on January 23, 1907, in Tokyo. A year thereafter his family moved to Kyoto, where he was raised and attended school. The fifth of seven children of Takuji and Koyuki Ogawa, Hideki came from a family of scholars. Although not inclined to science as he grew up, Hideki happened upon some books on modern physics while in high school and soon found quantum mechanics which was still a rapidly developing field at the time very...
I
In the case of octahedral complexes, general formula MX3B3, two isomers exist, facial fac and meridional mer , for example, fac and mer Co NH3 3 NO2 3 . A square-planar complex of formula MABXY has three isomers. An example is PdClBrNH3py , whose isomers were prepared by the Russian chemist I. Chernyaev in 1926. Polymerization isomers. In the case of octahedral complexes, formula MXxBJn, polymerization isomers are often possible. The value of n is greater than or equal to 1. Several compounds...
Artificial Sweeteners
There are presently four artificial, or synthetic, sweeteners that have been approved by the U.S. Food and Drug Administration FDA saccharin, aspartame, acesulfame-K, and sucralose. People use artificial sweeteners because they suffer from diseases such as diabetes mellitus, because they are concerned about dental caries and periodontal disease, or because they wish to lose or to avoid gaining weight. Artificial sweeteners in very small quantities give foods sweetness, and most are not...
Norepinephrine
Norepinephrine noradrenaline belongs to a family of biological compounds called catecholamines. These compounds are synthesized in sympathetic neurons and in the adrenal glands. Norepinephrine is produced from the catecholamine dopamine by the action of the enzyme dopamine -hydroxylase. This enzyme is responsible for the addition of a hydroxyl -OH group at the 3 carbon. See Figure 1. In certain cells of the adrenal glands, norepinephrine is chemically transformed into epinephrine adrenaline ,...
Squeezing Light Nearfield Scanning Optical Microscopy
The images that are generated by STM and AFM show structure but no true chemical composition. The details of the local chemistry on surfaces at the nanoscale level, however, are very important to understanding surface properties. Optical spectroscopy and microscopy provide a means of chemically identifying materials in conventional microscopy, however, the resolution limit is approximately half the wavelength of the light used to illuminate the sample. Thus, spatial resolutions are typically...
Huckels Rule
German physicist Erich Huckel used the molecular orbital theory to explain the stability of benzene and other aromatic compounds. Huckel's rule determines the number of tt electrons that give stability to an unsaturated planar ring according to the formula 4n 2. For benzene and its analogs, n 1 therefore, 4n 2 6 the aromatic sextet . The rule was calculated for single ring molecules and does not generally apply to multiring systems. Although many polycyclic aromatic molecules do follow Huckel's...
History Ytj
It is not clear who should be credited as the inventor of the first disposable diaper. The need for disposable diapers arose during World War II because of a shortage of cotton, which was used in traditional diapers. One of the first effective disposable diapers was created by Marion Donovan during the postwar baby boom. She is also credited with inventing the first plastic covering for traditional cloth diapers. Using this plastic covering made from a shower curtain and layers of tissue paper...
Aromaticity
The literal meaning of aromaticity is fragrance, but the word has a special meaning in chemistry. Aromaticity has to do with the unusual stability of the compound benzene and its derivatives, as well as certain other un-saturated ring compounds. The structures of these compounds are often shown to contain double bonds, but they do not actually behave like dou-reagent chemical used to cause a ble bonds. For example, reagents such as bromine react with benzene by specific chemical reaction...
Bibliography Epa
Buchholz, Fredric L., and Peppas, Nicholas A., eds. 1994 . Superabsorbent Polymers, Science and Technology. Washington, DC American Chemical Society. Lewis, R. J., Sr., ed. 1987 . Hawley's Condensed Chemical Dictionary, 14th edition. New York Wiley. Campbell, Todd. Soaking It In To Wash or Not to Wash You Decide. ABC-News.com 1999. Available from geek991011.html gt . Diapers and Wipes Frequently Asked Questions. Huggies. Kimberly-Clark Corp. Available from Richer, Carlos. History of the...