MU - Chemistry 210
Symmetry Elements of
Alkanes & Cycloalkanes



It is best to learn how to recognize symmetry elements by inspection of molecules that you are already familar with and that in fact have a lot of symmetry elements. So, here are a few molecules I want you to examine for symmetry elements. Build a model; it really, helps!

How many symmetry planes in methane? How many C3 rotational axes? How many C2 rotational axes? How many inversion centers?

Consider the staggered structure of ethane. What symmetry elements are there?

Consider the eclipsed structure of ethane. What symmetry elements are there?

Identify all symmetry elements in the all-staggered structure of propane.

Consider the trans conformation of butane. What symmetry elements are there?

Consider the gauche conformation of butane. What symmetry elements are there?

Consider the chair and the boat forms of cyclohexane and identify all symmetry elements.

Enjoy!