isomericadj.

/ʌɪsəʊˈmɛrɪk/

Etymology: Formed as isomer n. + -ic suffix; in modern French isomérique: after German isomerisch (Berzelius, Jahresbericht of Swed. Acad. Sciences, 31 March 1831).

a. Chemistry. Composed of the same elements in the same proportions, and having the same molecular weight, but forming different substances, with different properties (owing to the different grouping or arrangement of the constituent atoms). Said of two or more compounds, or of one compound in relation to another (const. with).This was the sense in which the term was introduced by Berzelius; but many later chemists (e.g. Wanklyn in Watts Dict. Chem. 1865) have applied it in a wider sense, so as to include also the polymeric compounds of Berzelius, i.e. those which have their elements in the same proportions, but the number of atoms in one a multiple of those in the other, e.g. butyric acid C₄H₈O₂, and aldehyde C₂H₄O; by these the isomeric compounds of Berzelius have been distinguished as metameric. More recent authors again (e.g. Tilden in Fownes' Chem. 1886) have used these terms more narrowly, subdividing the isomeric of Berzelius into isomeric strictly so called, and metameric; the former being compounds of the same molecular composition, which exhibit the same or closely similar decompositions and transformations, when subjected to the action of the same re-agents, such as the C₁₀H₈ hydrocarbons, the glucoses, the tartaric acids, etc.; the latter, those which exhibit dissimilar transformations under similar circumstances, as propionic acid, methyl acetate, and ethyl formate C₃H₆O₂.

ΘΚΠ

the world > matter > chemistry > isomerism > [adjective] > isomeric

isomeric1838

isomerous1864

1838 T. Thomson Chem. Org. Bodies 605 From the analysis of this substance [benzoin] it appears to be isomeric with the hydret of benzoyl.

1855 W. R. Grove On Correlation Physical Forces (ed. 3) 141 These..solutions are what is termed isomeric, that is, have as far as can be discovered the same chemical constitution.

1865–72 H. Watts Dict. Chem. III. 415 Two or more different bodies which are composed of the same elements, and of the same proportions of those elements (i.e. which have the same percentage composition) are said to be isomeric.

c1865 J. Wylde Circle of Sci. I. 311/2 Isomeric bodies have similar chemical constituents in the same proportions, and yet their external form may differ, as in sugar and starch.

1880 E. Cleminshaw tr. C. A. Wurtz Atomic Theory 294 We may..imagine isomeric compounds to be produced, according to the place occupied by the atoms fixed in the molecule.

1882 Gilburt in Jrnl. Quekett Club 2nd Ser. i. 27 We have already seen that cellulose, sugar, starch, and inulin, are isomeric with each other.

1892 H. F. Morley & M. M. P. Muir Watts' Dict. Chem. (rev. ed.) III. 88/2 According to our modern conceptions, truly isomeric substances..are equi-molecular compounds containing identical radicles arranged in relatively different modes; and..bearing in mind that it was obviously the intention of Berzelius to limit the scope of the expression, the term isomeric should be used only with reference to such compounds.

b. Physics. Of, pertaining to, or designating nuclear isomers; isomeric transition, a radioactive transition from a metastable state to a lower energy state of the same nuclide.

ΘΚΠ

the world > matter > physics > atomic nucleus > radioactive isotope > radioactive nuclide > [adjective] > relating to isomer

isomeric1934

1934 Physical Rev. 45 729/1 Another consequence of the introduction of negative protons is the possibility of the existence of isomeric nuclei, that is, nuclei with the same charge and mass but different internal structure.

1937 Physical Rev. 51 1011 The 18 minute, 4·2 hour, and 35 hour activities must all belong to Br⁸⁰ and Br⁸², i.e. one of these isotopes appears to exist in two isomeric forms, from which it decays with different periods.

1950 S. Glasstone Sourcebk. Atomic Energy x. 276/1 Over seventy examples of nuclear isomerism have been discovered, and the phenomenon of decay by isomeric transition, that is, by the spontaneous conversion of one nuclear isomer into another, has been elucidated. In most instances there are isomeric pairs only, but triple isomerism has been observed in a few cases.

1955 R. D. Evans Atomic Nucleus vi. 231 By the usual definition, an isomeric level is one whose half-period is ‘measurably’ long.

1970 P. Marmier & E. Sheldon Physics of Nuclei & Particles II. xv. 1276 Those nuclei whose ground-state configuration is modified by the preferential-filling rule would be expected to display low-lying excited states whose configuration corresponds to that of an unmodified ground state; because of the large spin change occasioned by this effect, the excited state is usually an isomeric state.

2. Comparative Anatomy. Pertaining to or of the nature of an isomere; homologous.

ΘΚΠ

the world > life > the body > external parts of body > limb > [adjective] > corresponding part

isomeric1890

the world > life > biology > biological processes > genetic activity > heredity or hereditary descent > [adjective] > resemblance between different organisms

homologous1846

homological1849

homoplastic1870

parhomologous1888

isomeric1890

homoeomorphous1895

syntechnic1902

homoeomorphic1923

1890 Cent. Dict. (at cited word) Isomeric segments of the limbs.

Derivatives

isoˈmerical adj. = isomeric adj.

isoˈmerically adv. (In recent dictionaries.)

This entry has not yet been fully updated (first published 1900; most recently modified version published online December 2019).

单词	isomeric
释义	isomericadj. /ʌɪsəʊˈmɛrɪk/ Etymology: Formed as isomer n. + -ic suffix; in modern French isomérique: after German isomerisch (Berzelius, Jahresbericht of Swed. Acad. Sciences, 31 March 1831). 1. a. Chemistry. Composed of the same elements in the same proportions, and having the same molecular weight, but forming different substances, with different properties (owing to the different grouping or arrangement of the constituent atoms). Said of two or more compounds, or of one compound in relation to another (const. with).This was the sense in which the term was introduced by Berzelius; but many later chemists (e.g. Wanklyn in Watts Dict. Chem. 1865) have applied it in a wider sense, so as to include also the polymeric compounds of Berzelius, i.e. those which have their elements in the same proportions, but the number of atoms in one a multiple of those in the other, e.g. butyric acid C₄H₈O₂, and aldehyde C₂H₄O; by these the isomeric compounds of Berzelius have been distinguished as metameric. More recent authors again (e.g. Tilden in Fownes' Chem. 1886) have used these terms more narrowly, subdividing the isomeric of Berzelius into isomeric strictly so called, and metameric; the former being compounds of the same molecular composition, which exhibit the same or closely similar decompositions and transformations, when subjected to the action of the same re-agents, such as the C₁₀H₈ hydrocarbons, the glucoses, the tartaric acids, etc.; the latter, those which exhibit dissimilar transformations under similar circumstances, as propionic acid, methyl acetate, and ethyl formate C₃H₆O₂. ΘΚΠ the world > matter > chemistry > isomerism > [adjective] > isomeric isomeric1838 isomerous1864 1838 T. Thomson Chem. Org. Bodies 605 From the analysis of this substance [benzoin] it appears to be isomeric with the hydret of benzoyl. 1855 W. R. Grove On Correlation Physical Forces (ed. 3) 141 These..solutions are what is termed isomeric, that is, have as far as can be discovered the same chemical constitution. 1865–72 H. Watts Dict. Chem. III. 415 Two or more different bodies which are composed of the same elements, and of the same proportions of those elements (i.e. which have the same percentage composition) are said to be isomeric. c1865 J. Wylde Circle of Sci. I. 311/2 Isomeric bodies have similar chemical constituents in the same proportions, and yet their external form may differ, as in sugar and starch. 1880 E. Cleminshaw tr. C. A. Wurtz Atomic Theory 294 We may..imagine isomeric compounds to be produced, according to the place occupied by the atoms fixed in the molecule. 1882 Gilburt in Jrnl. Quekett Club 2nd Ser. i. 27 We have already seen that cellulose, sugar, starch, and inulin, are isomeric with each other. 1892 H. F. Morley & M. M. P. Muir Watts' Dict. Chem. (rev. ed.) III. 88/2 According to our modern conceptions, truly isomeric substances..are equi-molecular compounds containing identical radicles arranged in relatively different modes; and..bearing in mind that it was obviously the intention of Berzelius to limit the scope of the expression, the term isomeric should be used only with reference to such compounds. b. Physics. Of, pertaining to, or designating nuclear isomers; isomeric transition, a radioactive transition from a metastable state to a lower energy state of the same nuclide. ΘΚΠ the world > matter > physics > atomic nucleus > radioactive isotope > radioactive nuclide > [adjective] > relating to isomer isomeric1934 1934 Physical Rev. 45 729/1 Another consequence of the introduction of negative protons is the possibility of the existence of isomeric nuclei, that is, nuclei with the same charge and mass but different internal structure. 1937 Physical Rev. 51 1011 The 18 minute, 4·2 hour, and 35 hour activities must all belong to Br⁸⁰ and Br⁸², i.e. one of these isotopes appears to exist in two isomeric forms, from which it decays with different periods. 1950 S. Glasstone Sourcebk. Atomic Energy x. 276/1 Over seventy examples of nuclear isomerism have been discovered, and the phenomenon of decay by isomeric transition, that is, by the spontaneous conversion of one nuclear isomer into another, has been elucidated. In most instances there are isomeric pairs only, but triple isomerism has been observed in a few cases. 1955 R. D. Evans Atomic Nucleus vi. 231 By the usual definition, an isomeric level is one whose half-period is ‘measurably’ long. 1970 P. Marmier & E. Sheldon Physics of Nuclei & Particles II. xv. 1276 Those nuclei whose ground-state configuration is modified by the preferential-filling rule would be expected to display low-lying excited states whose configuration corresponds to that of an unmodified ground state; because of the large spin change occasioned by this effect, the excited state is usually an isomeric state. 2. Comparative Anatomy. Pertaining to or of the nature of an isomere; homologous. ΘΚΠ the world > life > the body > external parts of body > limb > [adjective] > corresponding part isomeric1890 the world > life > biology > biological processes > genetic activity > heredity or hereditary descent > [adjective] > resemblance between different organisms homologous1846 homological1849 homoplastic1870 parhomologous1888 isomeric1890 homoeomorphous1895 syntechnic1902 homoeomorphic1923 1890 Cent. Dict. (at cited word) Isomeric segments of the limbs. Derivatives isoˈmerical adj. = isomeric adj. isoˈmerically adv. (In recent dictionaries.) This entry has not yet been fully updated (first published 1900; most recently modified version published online December 2019). < adj.1838
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