Atoms and Molecules

Molecules and Chemical Bonds

What are some common structures/geometries for molecules?

The study of chemistry has benefited greatly from knowledge of properties relating to the geometries and, especially, the symmetries of molecules. To get a sense of what shapes molecules adopt, it’s worth taking a look at a few of the geometries that come up often in the study of chemistry.


One commonly encountered geometry is that of a tetrahedron. Methane has the molecular formula CH4 and exists in a tetrahedral geometry with angles of approximately 109 degrees between each pair of C–H bonds.


Linear geometries are also relatively common. Carbon dioxide has the molecular formula CO2 and exists in a linear geometry with a 180-degree angle between the CO bonds.


One last geometry we’ll look at here is a planar geometry. The molecule BH3 provides one example of a planar geometry, and in this case the BH bonds are separated by angles of 120 degrees. There are also planar molecules with four bonds in a plane, and in those cases the bonds are separated by angles of 90 degrees.


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