The simplest test for chirality is symmetry. If a molecule has an internal line of symmetry, it is ** achiral**.

Concept #1: How and when to use the internal line of symmetry test.

- Unfortunately, this test is only practical for
__rings__.

This is what we call a Hawthorne Projection. It’s a way to visualize rings in 3D. It’s really easy to tell if these molecules have a plane of symmetry or not.

Example #1: Does the following molecule contain a stereogenic center? Is it chiral?

This is a 2D ringed structure. It’s super easy to predict a plane of symmetry on this one.

Example #2: Does the following molecule contain a stereogenic center? Is it chiral?

The plane of symmetry is allowed to split atoms! Just look for any line that can create equal images on both sides.

Example #3: Does the following molecule contain a stereogenic center? Is it chiral?

Do you think TEST 1 will work well on this molecule? Why or why not?

Example #4: Does the following molecule contain a stereogenic center? Is it chiral?