Why Do You Need to Know This Material? The shapes of molecules determine
their odors, their tastes, and their actions as drugs. Molecular shape plays an essential
role in the reactions that take place throughout our bodies and are necessary for life. It
also affects the properties of the materials around us, including their physical states and
their solubilities. Perception, thinking, and learning depend on the shapes of molecules
and how they change. Modern theories of the electronic structures of molecules can be
extended to describe metals and semiconductors, and so the information in this chapter
is also at the root of the development of new technologies.