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isomer Syllabification: i·so·mer
Pronunciation: /ˈīsəmər/

Definition of isomer in English:


1 Chemistry Each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties.
Example sentences
  • However, several research groups have suggested cis isomers of lycopene are better absorbed than the all-trans form.
  • Conjugated linoleic acid is a mixture of positional and geometric isomers of linoleic acid.
  • In 1907, he synthesized a pair of geometric isomers that confirmed his predictions.
2 Physics Each of two or more atomic nuclei that have the same atomic number and the same mass number but different energy states.
Example sentences
  • The Texas collaboration purports to have demonstrated that a 10-keV x-ray photon can precipitate a prompt 2.45 - MeV gamma-ray cascade as the isomer Hf m2 relaxes to the stable nuclear ground state.
  • Constitutional isomers are isomers that have different atomic connectivities.
  • One form is called the (+) isomer because it rotates polarized light to the right, in a positive direction.


Pronunciation: /ˌīsəˈmerik/
Example sentences
  • There is also a significant difference according to the isomeric structure (a = Rp or b = Sp) for the samples 1a, b and 2a, b.
  • At very high temperatures, part of the Lu decay to Hf bypasses the conventional slow route, and goes into an isomeric state which has a half-life of only 3.68 hours.
  • The results reveal that metal cation binding affects the protein conformation, the retinal isomeric composition as well as lipid head groups.
Pronunciation: /īˈsäməˌrizəm/
Example sentences
  • The authors concluded that this isomerism could explain the differential biological effects of CHH (hyperglycemia and molt-inhibition).
  • The second major type of isomerism is stereoisomerism.
  • This chain disorder results from trans-gauche isomerism about the C-C bonds in the lipid chains.
Pronunciation: /īˈsäməˌrīz/
Example sentences
  • After binding to a blunt DNA end to form an initiation complex, the complex isomerizes to one of several possible unwinding states.
  • In response to absorption of a photon, the 11-cis-retinal isomerizes to the all-trans conformation, inducing helix 3 to shift toward the extracellular side.
  • Cannabidiol is extracted from fiber cannabis and isomerized to dronabinol.


Mid 19th century: from Greek isomerēs 'sharing equally', from isos 'equal' + meros 'a share'.

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