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Symmetry Summary

Symmetry Summary. GLY 4200 Lab 5 - Fall, 2012. Definitions. Motif : the fundamental part of a symmetric design that, when repeated, creates the whole pattern Operation : some act that reproduces the motif to create the pattern Element : an operation located at a particular point in space.

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Symmetry Summary

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  1. Symmetry Summary GLY 4200 Lab 5 - Fall, 2012

  2. Definitions • Motif: the fundamental part of a symmetric design that, when repeated, creates the whole pattern • Operation: some act that reproduces the motif to create the pattern • Element: an operation located at a particular point in space

  3. 2-D Symmetrical Pattern

  4. Symmetrical Pattern • A pattern consisting of two motifs

  5. Symmetrical Pattern • is the symbol for a two-fold rotation, known as a diad

  6. 180 Degree Rotation • Rotate in two steps

  7. Three Fold Rotation • 360o/3 = 120o rotation to reproduce a motif in a symmetrical pattern • is the symbol for a three-fold rotation, known as a triad

  8. N-Fold Rotations • Respectively, 360o, 180o, 120o, 90o, and 60o

  9. Reflection • Reflection across a “mirror plane” reproduces a motif • is the symbol for a mirror plane

  10. Inversion • Inversion through a center to reproduce a motif in a symmetrical pattern • = symbol for an inversion center

  11. Lab Exercise • For lab, examine each object • Report all symmetry • For rotation, the fold and number of each type of rotational axis present • Example: 1A4, 2A2 • For reflection, total number of mirror planes present, if any • For inversion, yes or no (does it have a center or doesn’t it?)

  12. Results • Keep a copy of your results for next week’s lab – you need to turn in one, and have one copy for lab 6

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