In the Classroom
A Versatile Puzzle for Use as a Teaching Aid in Organic Chemistry at Secondary School David Follows Department of Chemistry, Winchester College, Winchester, Hampshire, United Kingdom SO23 9LX
[email protected] Chemistry can be approached as one huge puzzle, and many students enjoy solving puzzles in which work seems like a game (1). A search of the Internet and journals has revealed no previous example of this type of puzzle. The basic idea is that by considering organic molecules as connected small groups of atoms, and treating those like letters in words, an analogue to the common word search can be created. The number and range of associated questions is limitless. The grid could take two forms: with or without bonds between groups. The original idea has the bonds in place and is easier to follow, as shown in Figure 1. Questions that might be asked of students include a variety of possible types to test or drill a range of skills. Some examples are • How many alkanes are present? • Which two molecules are isomers? • How many different types of molecule are there that contain oxygen? • Which three molecules could make addition polymers? • How many chloroalkanes are there? • Which molecule is acidic? • Shade lightly the squares containing heptane, 2-chlorobutane, and hexan-3-ol. • How many oxygen atoms are present in total? • Which molecule has empirical formula C2H5? • How many molecules contain three carbon atoms? • List the alcohols present by name. • Which molecule has the highest relative molecular mass? • How many double bonds are present in total? • Which molecule has a geometric isomer? • Which molecules have optical isomers? • Which molecule contains the fewest atoms?
The list could go on, and for more advanced students, other functional groups are easily added. This particular example (Figure 1) has been used with more than one age and ability group and garnered positive feedback from the students. This puzzle can be used to teach various concepts in organic chemistry: (i) “bends” around single bonds in a molecule do not affect the molecule's name or identity, (ii) naming molecules and identifying functional groups, (iii) isomerism of different types, (iv) an indication of the variety of possible organic chemicals,
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Figure 1. An example grid.
(v) the importance of carbon chains, (vi) the prevalence of hydrogen, and (vii) familiarity with valence numbers. The grid is simply produced by drawing a square in an accessory such as Paint, and then reproducing it and filling in groups. Squares may then be copied and stuck together or overlaid onto a grid in Excel or Paint. Without bonds between squares, the grid would more closely resemble a traditional word search, and groups could be represented by formulas. Molecules would be found in straight lines forward, backward, upward, downward, or diagonally. However, I do not believe this would be quite so useful as it would not reinforce teaching points i and vii above, and precludes branched or bent molecules. Acknowledgment Many thanks to Chris Evans for collecting and sharing a number of valuable Web-based Chemistry resources at http:// www.btinternet.com/~chemistry.diagrams/. Literature Cited 1. Russell, J. V. J. Chem. Educ. 1999, 76, 481.
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r 2010 American Chemical Society and Division of Chemical Education, Inc. pubs.acs.org/jchemeduc Vol. 87 No. 4 April 2010 10.1021/ed800127w Published on Web 03/09/2010
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Journal of Chemical Education
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