Group
Name:
Group
Detailed information:
(1) One of the major classes or divisions into which elements are arranged in the periodic table (vertical columns). The classification is made according to the properties of the elements, those whose properties are similar occupying one group. Groups I through VII are divided into subgroups (A and B), but group VIII, which contains the nobel gases, is not so divided.See Periodic Table.Note: Though often loosely so used, the word group should not be applied to a number of elements of similar properties that are not actual groups in the periodic table; the proper term for these is series, e.g., lanthanide series, rare-earth series, etc.(2) A combination of two or more closely associated elements that tend to remain together in reactions, usually behaving chemically as if they were individual entities, i.e., in respect to valence, ionization, and related properties. Among the more familiar are OH (hydroxyl), COOH (carboxyl), CO3 (carbonate), NH4 (ammonium), SO4 (sulfate), CH3 and homologs (methyl, etc.), SH (sulfhydryl), and CO (carbonyl). When a group acquires an electric charge it is called a radical.(3) Any combination of elements that has a specific functional property, for example, a chromophore group in dyes.
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