Formulae, chemical

Another example of deahng with molecular structure input/output can be found in the early 1980s in Boehiinger Ingelheim. Their CBF (Chemical and Biology Facts) system [44] contained a special microprocessormolecular structures. Moreover, their IBM-type printer chain unit had been equipped with special chemical characters and it was able to print chemical formulas. 

Linus Pauling is portrayed on this 1977 Volta stamp The chemical formulas depict the two resonance forms of ben zene and the explosion in the background symbolizes Pauling s efforts to limit the testing of nuclear weapons... 

Lewis structure (Section 1 3) A chemical formula in which electrons are represented by dots Two dots (or a line) be tween two atoms represent a covalent bond in a Lewis structure Unshared electrons are explicitly shown and sta ble Lewis structures are those in which the octet rule is sat isfied... 

Molecular formula (Section 1 7) Chemical formula in which subscnpts are used to indicate the number of atoms of each element present in one molecule In organic compounds carbon is cited first hydrogen second and the remaining el ements in alphabetical order... 

Structural prefixes should be italicized and connected with the chemical formula by a hyphen cis-, trans-, anti-, syn-, cyclo-, catena-, o- or ortho-, m- or meta-, p- or para-, sec- (secondary), tert-(tertiary), v- (vicinal), meso-, as- for asymmetrical, and 3- for symmetrical. 

Exact numbers, such as the stoichiometric coefficients in a chemical formula or reaction, and unit conversion factors, have an infinite number of significant figures. A mole of CaCb, for example, contains exactly two moles of chloride and one mole of calcium. In the equality... 

The system of indexing molecules is, first, according to the number of atoms in the molecule. Then, with the chemical formula written in what seems a natural way, they are ordered alphabetically in order of the atoms as they appear in the formula. 

For most molecules with more than three atoms the name of the molecule is given in parentheses after the chemical formula. In most cases, only the common and not the systematic name is given so that, for example, C2H4 is called ethylene and not ethene. 

Perovskites have the chemical formula ABO, where A is an 8- to 12-coordinated cation such as an alkaU or alkaline earth, and B is a small, octahedraHy coordinated high valence metal such as Ti, Zr, Nb, or Ta. Glass-ceramics based on perovskite crystals ate characteri2ed by their unusual dielectric and electrooptic properties. Examples include highly crystalline niobate glass-ceramics which exhibit nonlinear optical properties (12), as well as titanate and niobate glass-ceramics with very high dielectric constants (11,14). 

Molecular-sieve zeoHtes of the most important aluminosiHcate variety can be represented by the chemical formula 2ln A1202 j)/Si02 wherejy is 2... 

Chemical Formula Boiling poiat, °C Odor threshold Toxicity properties, ppm Threshold limit IDLH coaceatratioa... 

Common name Chemical name Chemical formula Symbol Tallow Lard Coconu t Palm kernel Soybean... 

Polystyrene [9003-53-6] (PS), the parent of the styrene plastics family, is a high molecular weight linear polymer which, for commercial uses, consists of - 1000 styrene units. Its chemical formula (1), where n = - 1000, tells htde of its properties. 

Properties. Boron carbide has a rhombohedral stmcture consisting of an array of nearly regular icosahedra, each having twelve boron atoms at the vertices and three carbon atoms ia a linear chain outside the icosahedra (3,4,6,7). Thus a descriptive chemical formula would be [12075-36-4]. 

Mshland Chemicals Formula for the Cosmetics Industry Bulletin 1155, Ashland Chemical Co., Columbus, Ohio. 

AH of these metallic and nonmetallic ions join together in a compHcated array of salts and minerals called evaporites. Several evaporites usually crystalline simultaneously in a mixture. This often makes separation into pure chemicals difficult. A Hst of some of the mote common evaporites is given in Table 1, which also shows their chemical formulas and other mineral names. 

Mineral CAS Registry Chemical formula Crystalline Approximate Density, Cobalt Location... 

Two-Dimensional Representation of Chemical Structures. The lUPAC standardization of organic nomenclature allows automatic translation of a chemical s name into its chemical stmcture, or, conversely, the naming of a compound based on its stmcture. The chemical formula for a compound can be translated into its stmcture once a set of semantic rules for representation are estabUshed (26). The semantic rules and their appHcation have been described (27,28). The inverse problem, generating correct names from chemical stmctures, has been addressed (28) and explored for the specific case of naming condensed benzenoid hydrocarbons (29,30). 

An important approach to the graphic representation of molecules is the use of a connection table. A connection table is a data base that stores the available bond types and hybridizations for individual atoms. Using the chemical formula and the connection table, molecular stmctures may be generated through interactive graphics in a menu-driven environment (31—33) or by using a linear input of code words (34,35). The connection table approach may be carried to the next step, computer-aided molecular design (CAMD) (36). 

Fig. 5. Chemical formulas for metal complex dyes (a), 1 1 complex (b), 1 2 complex.

Thiourea dioxide, or formamidine sulfinic acid, is an oxygenated thiourea derivative synthesized by the oxidation of thiourea with hydrogen peroxide. It has the chemical formula (NH2)NHCS02H and is tautomeric. 

The reqmred values of are determined from the initial numbers of moles, and the values of dji come directly from the chemical formulas of the species. These are shown in the accompanying table. 

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