isomer

i·so·mer   (ī'sə-mər)    n.   Chemistry Any of two or more substances that are composed of the same elements in the same proportions but differ in properties because of differences in the arrangement of atoms. Physics Any of two or more nuclei with the same mass number and atomic number that have different radioactive properties and can exist in any of several energy states for a measurable period of time. [Greek īsomerēs, having equal share : īso-, iso- + meros, part, share; see (s)mer-2 in Indo-European roots.] i'so·mer'ic (-měr'ĭk) adj., i'so·mer'i·cal·ly adv.

Main Entry: iso·mer
Pronunciation: 'I-s&-m&r
Function: noun
1 : any of two or more compounds, radicals, or ions that contain the samenumber of atoms of the same elements but differ in structural arrangement and properties
2 : a nuclide isomeric with one or more others

isomer i·so·mer (ī'sə-mər)
n.

1. Any of two or more substances that are composed of the same elements in the same proportions but differ in properties because of differences in the arrangement of atoms.

2. Any of two or more nuclei with the same mass number and atomic number that have different radioactive properties and can exist in any of several energy states for a measurable period of time.

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i'so·mer'ic (-měr'ĭk) adj.