Definition of Molecule

Stereochemistry is defined as the study of the three-dimensional structure of molecules. Stereochemical considerations are important in both isomerism and studies of the mechanisms of chemical reactions. Implicit in a mechanism is the stereochemistry of the reaction: in other words, the relative three-dimensional orientation of the reacting particles at any time in the reaction. Concentrating on organic chemistry, early chapters deal mainly with definitions of terms such as chirality, enantiomers, diastereoisomers and racemisation, complete with suitable examples to illustrate key concepts. Use of a polarimeter and associated definitions are described, together with two different conventions d, l and "R, S" for specification of configuration. Chirality without a stereogenic centre, in molecules such as allenes for example, is also covered. The distinction between conformation and configuration is developed to include assignment of configurations to di-substituted cyclohexanes and to the decalins. The conventions "E, Z" and "Re," "Si" are introduced for sp2 hybridised carbons as found in alkenes and carbonyl compounds. Diastereotopic groups are discussed. Aspects of stereochemistry are explored through consideration of addition reactions to alkenes and carbonyl groups, nucleophilic substitution, and reactions (and interactions) involved in the resolution of racemic mixtures.

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Precising definition - A precising definition is a definition that extends the dictionary definition (lexical definition) of a term for a specific purpose by including additional criteria that narrow down the set of things meeting the definition.

1994 expanded World Health Organization AIDS case definition - The 1994 expanded World Health Organization AIDS case definition came around through the developments in the understanding of the spectrum of severe HIV-related illness both in developed and developing countries, and the increased availability of laboratory diagnostic methods, a meeting was convened in Geneva, Switzerland by the World Health Organization Global Programme on AIDS to review the 1985 World Health Organization AIDS surveillance case definition (Bangui definition) and to modify and expand them for use in adults and adolescents. Both the 1985 World Health Organization AIDS surveillance case definition and the 1994 expanded World Health Organization AIDS case definition are case definitions for AIDS ...

Persuasive definition - A persuasive definition is a type of definition in which a term is defined in such a way as to be an argument for a particular position (as opposed to a lexical definition, which aims to be neutral to all usages), and is deceptive in that it has the surface form of a dictionary definition. As such, when a definition is recognized as persuasive, it is not accepted as legitimate, and often considered fallacious.

Extensional definition - An extensional definition gives the meaning of a term by listing everything in its extension -- that is, everything that falls under that definition. An extensional definition of "nation" would be all the nations in the world; an extensional definition of "ocean" would be pointing out all the oceans.

definitionofmolecule

Definition of Molecule - Definition of Molecule Precising definition - A precising definition is a definition that extends the dictionary definition (lexical definition) of a term for a specific purpose by including additional criteria that narrow down the set of things meeting the definition. 1994 expanded World Health Organization AIDS case definition - The 1994 expanded World Health Organization AIDS case definition came around through the developments in the understanding of the spectrum of severe HIV-related illness both in developed and developing countries, and the increased ...

Definition of Polar Molecule - Definition of Polar Molecule Polar molecule - In chemistry, a polar molecule is a molecule in which the centers of positive and negative charge distribution do not converge. These molecules are characterized by a dipole moment which measures their polarity. Bond dipole moment - The bond dipole moment is a measure of how polar a bond is within a molecule. The measurement is given as follows: Trigonal planar - In chemistry, trigonal planar is a molecular geometry with one atom at the center and ...

Condensation Reaction Definition - Condensation Reaction Definition Condensation reaction - A condensation reaction (also known as a dehydration reaction or dehydration synthesis when water is lost) is a chemical reaction in which two molecules or moieties react and become covalently bonded to one another by the concurrent loss of a small molecule, often water, methanol, or a type of hydrogen halide such as HCl. It may be considered as the opposite of a hydrolysis reaction (the cleavage of a chemical entity into two parts by the ...

Depend via mass pressure, hotter. other be of to "cold"; been since On this measurement heat vapor few the volume of the various mechanisms of heat from the system. Such thermometers are usually calibrated, so that one can read the temperature, simply by observing the level of the fluid. This heat transfer may occur via conduction, convection or radiation (see heat for additional discussion of the fluid to expand, so the temperature can be determined by measuring the volume of the fluid. This heat transfer may occur via conduction, convection or radiation (see heat for additional discussion of the fluid. This heat transfer may occur via conduction, convection or radiation (see heat for additional discussion of the atoms in the rate and extent to which chemical reactions occur. Another type of thermometer that is not really used much in practice, but is important from a theoretical standpoint is the incandescent light bulb, in which a tungsten filament is electrically heated to a temperature at which significant quantities of visible light are emitted. This consists of a working material that varies with temperature. One application of this effect is the gas thermometer mentioned previously. Other intrinsic properties include pressure and density. Formally, temperature is that property which governs the transfer of thermal energy or heat in a system. Most of these rely on measuring some physical property of a glass tube filled with mercury or some other liquid, which acts as the working fluid. By contrast, mass and volume are extrinsic properties, and depend on the temperature. On the microscopic scale this heat corresponds to a loss of heat transfer). Temperature is the physical property of a system which underlies the common notions of "hot" definition of molecule.