Internal Energy

Internal Energy is sum of
Kinetic energy of molecules	Potential energy of molecules
Due to motion of molecules	Due to the stretching and compression of the intermolecular forces as the molecules vibrate.
Directly proportional to temperature. The higher the temperature, the more vigorous the movement of the molecules.	Related to change of state
Heat capacity	Latent heat

The amount of potential energy stored in the bonds depends on the force between the particles and how far apart the particles are.

Note that solids have least amount of potential energy while gases have most amount of potential energy.
Reason will be discussed at Heating Curve.

Previous: Thermal Properties of Matter

Next: Heat Capacity v.s Specific Heat Capacity