Chiral Carbon

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1. The Chiral carbon Atom

Learning Objectives
Having completed this unit you should be able to:
1. Distinguish symmetrical and asymmetrical objects
2. Distinguish chiral carbon atoms
3. Interpret and draw three-dimensional representations of organic compounds
4. Discuss the importance of chirality in organic compounds
5. Define the emboldened terms within the text.

Learning Resources
In addition to these web pages* you will require access to your Molymod kit. The web pages contain interactive models that allow molecules to visualised in three dimensions. To view these models* you will require the Chime `plug-in' for your browser. Instructions on how to obtain Chime and an introduction to its functionality are found here. These web pages are an alternative to the paper-based text* they do not contain extra material.

Prior Learning
Before studying this text* you should be familiar with the concepts of bonds* molecules and the basic geometries found in organic compounds. This information was presented in course ST240 Our Chemical Environment. You might find it useful to review section 7.5 of Book 1 (`Models of Matter') of ST240 prior to studying this unit.

1.1 Symmetry and Asymmetry
Chiral carbon atoms are those that do not possess a centre of symmetry. Before progressing to look at asymmetrical carbon atoms* it is worth spending a short time developing an understanding of symmetry and asymmetry in the everyday world.

An object is symmetrical if there is a plane* axis or centre about which there is an exact correspondence of parts of the object. Such objects are said to have a plane* axis or centre of symmetry respectively. For example* if you draw a line running front to back down the middle of a chair* the components of the chair are exactly the same on each side* and equally spaced from the line. A chair thus has a plane of symmetry. Another way of recognising symmetrical objects is that they are indistinguishable from their mirror images. Imagine placing two identical chairs facing each other. They are mirror images* however when placed side by side they are indistinguishable