Chemistry for Everyone
A Picture Is Worth 1000 Words: The BLT in Crystallography Arthur M. Lesk Department of Haematology, University of Cambridge School of Clinical Medicine, Wellcome/MRC Building, Hills Road, Cambridge CB2 2XY, UK
In explaining descriptions of crystals, many authors have emphasized the idea that Nature makes crystals, but human beings draw unit cell boundaries. The accompanying figure contains a useful classroom demonstration to drive this point home. It shows a planar crystalline array of alternating pictures of a tomato and a portion of bacon. In the context of a lesson on crystal structure, students readily identify this picture as a “B.L.T.”—bacon, lattice, and tomato—but do not appreciate the serious significance of the pun until they are asked to point out the bacon, which they do; then asked to point out the tomato, which they do; and finally asked to point out the lattice—AHA! The lattice is not visible. Acknowledgment I thank the Wellcome Trust for support.
JChemEd.chem.wisc.edu • Vol. 77 No. 11 November 2000 • Journal of Chemical Education
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