and identify the symmetry elements in each. For example, when describing
the cube, state "mirror plane in (110)", or make drawings of the faces of the cube with the symmetry elements shown.
the point group of each object.
to which crystal system each of the models must belong.
in a description of the symmetry elements in each object, the point
group of the object, and the appropriate crystal system. Make sure
your drawings are relatively neat and legible. A formal lab write-up is not required. If you were not in
lab, or would like to get additional copies of the cut-out patterns
for the 3-d objects, you can download them here (see below).
Chapter 2: #1, #5, #6 (reproduced below)
1. Consider two mirror planes that intersect at f = 90°. Using a geometrical representation of two planes, establish which symmetry element(s) appear(s) as the result of this combination of mirror planes. What is(are) the location(s) of new symmetry element(s)? Name the point gorup symmetry formed by this combination of symmetry elements.
5. Determine both the crystal systems and point group symmetry of an ideal brick in which a =/= b =/= c and a = b = g = 90°.
6. Determine both the crystal system and point group symmetry of the benzene molecule, C6H6. Treat atoms as spheres, not dimensionless points.
Preparation for X-ray Data Analysis:
Install Origin Software. It can be downloaded from the company website www.originlab.com. A one-year student license can be purchased for $50. A sample ascii data file of diffraction data is available here. Plot this using properly label axes and provide a meaningful figure caption: “Figure 1. X-ray powder diffraction pattern collected from xxxx at xxx C using CuKa radiation (Panalytical X’Pert Pro) over the two-theta range xxx to xxx.” The material examined is Rb5H3(SO4)4, and data were collected at 190C.
Models (pdf files)
bipyramidal crystal (rose)
dodecahedron - irregular (yellow)