isomerism

isomerism
The existence of a chemical compound in two or more forms that are identical with respect to percentage composition but differ as to the positions of one or more atoms within the molecules, as well as in physical and chemical properties.
- geometric i. a form of i. displayed by unsaturated or ring compounds where free rotation about a bond (usually a carbon-carbon bond) is restricted; e.g., the i. of a cis- or trans- compound as in oleic acid and elaidic acid. Cf.:cis-, entgegen, trans-, zusammen.
- optic i. stereoisomerism involving the arrangement of substituents about an asymmetric atom or atoms (usually carbon) so that there is a difference in the behavior of the various isomers with regard to the extent of their rotation of the plane of polarized light. Cf.:stereoisomerism.
- structural i. i. involving the same atoms in different arrangements; e.g., the butyric acid s, leucine and isoleucine, glucose and fructose.

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isom·er·ism ī-'säm-ə-.riz-əm n
1) the relation of two or more chemical species that are isomers
2) the relation of two or more nuclides with the same mass numbers and atomic numbers but different energy states and rates of radioactive decay

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isom·e·rism (i-somґə-riz-əm) [iso- + Gr. meros part] the relationship that exists between two or more different chemical compounds that have the same molecular formula; it is divided into two broad classes: constitutional i. and stereoisomerism (q.v.). isomeric adj

Medical dictionary. 2011.

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  • isomerism — [ī säm′ər iz΄əm] n. the state or relation of isomers …   English World dictionary

  • isomerism — /uy som euh riz euhm/, n. 1. Chem. the relation of two or more compounds, radicals, or ions that are composed of the same kinds and numbers of atoms but differ from each other in structural arrangement (structural isomerism), as CH3OCH3 and… …   Universalium

  • isomerism — izomerija statusas T sritis chemija apibrėžtis Vienodos sudėties ir molekulinės masės junginių gebėjimas turėti skirtingą struktūrą ir savybes. atitikmenys: angl. isomerism rus. изомерия …   Chemijos terminų aiškinamasis žodynas

  • isomerism — izomerija statusas T sritis fizika atitikmenys: angl. isomery; isomerism vok. Isomerie, f rus. изомерия, f pranc. isomérie, f …   Fizikos terminų žodynas

  • isomerism — isomer ► NOUN 1) Chemistry each of two or more compounds with the same formula but a different arrangement of atoms and different properties. 2) Physics each of two or more atomic nuclei with the same atomic number and mass number but different… …   English terms dictionary

  • isomerism — noun Date: 1838 1. the relationship of two or more chemical species that are isomers 2. the relation of two or more nuclides with the same mass numbers and atomic numbers but different energy states and rates of radioactive decay …   New Collegiate Dictionary

  • isomerism — noun a) the phenomenon of the existence of isomers the existence of different substances with the same molecular formulae b) the interconversion of isomers …   Wiktionary

  • isomerism — the phenomenon whereby two or more polymer molecules or mer units have the same composition but different structural arrangements and properties …   Mechanics glossary

  • isomerism — n. connection between two or more chemical compounds which have the same number and kind of atoms but differ in structural arrangement (Chemistry) …   English contemporary dictionary

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