Geometrical equivalence

{
  "id": "MLC-T-CHM-004854",
  "term": "Geometrical equivalence",
  "field": "Chemistry",
  "definition": "The symmetry correspondence between units of the same polymer chain, in which one unit is carried onto another by a symmetry operation of the chain, such as a translation along the axis or a screw rotation. The symmetry elements are always tied to the chain axis. Units related this way are necessarily chemically identical, but chemically identical units need not be geometrically equivalent, because a chain can adopt conformations that do not repeat at every unit.",
  "subject": "Polymer",
  "see_also": [
    "line repetition groups"
  ],
  "references": [
    "Purple Book, 1st ed., p. 77 (http://old.iupac.org/publications/books/author/metanomski.html)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/geometrical-equivalence/"
}