Symmetry Summary
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1 Symmetry Summary GLY 4200 Lab 5 - Fall, 2012
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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. - PowerPoint PPT Presentation
Transcript of Symmetry Summary
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Symmetry Summary
GLY 4200
Lab 5 - Fall, 2012
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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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2-D Symmetrical Pattern
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Symmetrical Pattern
• A pattern consisting of two motifs
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Symmetrical Pattern
• is the symbol for a two-fold rotation, known as a diad
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180 Degree Rotation
• Rotate in two steps
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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
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N-Fold Rotations
• Respectively, 360o, 180o, 120o, 90o, and 60o
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Reflection
• Reflection across a “mirror plane” reproduces a motif
• is the symbol for a mirror plane
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Inversion
• Inversion through a center to reproduce a motif in a symmetrical pattern
• = symbol for an inversion center
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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?)
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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
