CHEMISTRY COMMUNITY

Can someone explain to me why heat capacity increases as molecular complexity increases?

I believe it has to do with the increase in molecular motion and disorder.

From what I understand, there are three forms of movement that affect the internal energy of a molecule, and therefore the heat capacity. These are: translational, linear rotational, and nonlinear rotational. For more complex molecules, all three motions are occurring and therefore the molecule has more internal energy and a higher heat capacity.

The solutions manual explains that as more atoms are present in the molecule, there are more possible bond vibrations that can absorb added energy