Teachers' guide 2 - National STEM Centre

Appendix 3
Models and other visual aids
Structure models for the course
In any serious attempt to assist students to understand the three-dimensional
structures of substances the need to use models should not need justifying. Any
teacher who attempts to construct structure models will rapidly find that a
detailed understanding of the spatial relationships between atoms is necessary
in order to complete them successfully. Therefore students will best learn about
structures if they construct models for themselves, and a . model workshop' is
likely to be an annual feature of this chemistry course.
Given that the objective is to construct models each year it is necessary either
to have component parts (figure M.l) from which models can be readily
assembled when required and then demounted for the following year, or to
construct models from cheap materials which can be regarded as expendable
and perhaps sold to their constructors to defray the cost. There are, however, a
number of models that the teacher will wish to have in permanent form because
of their complexity or because their main teaching use will be for display and
discussion rather than for consideration of how the structure is built up.
Figure M.I
Examples of structure models. Back row: demountable ball-and-spoke (Crystal structures); spacefilling,
ionic structures (Catalin); miniature models (Beevers); Linell ball-and-spring (Gallenkamp).
Front row: Stuart-type organic set (Griffin and George); Dreiding stereomodels (Rinco, USA);
space-filling covalent set (Catalin).
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