The Law of Equipartition of Energy states that for a system in thermal equilibrium at temperature $T$, the total energy is distributed equally among all its degrees of freedom.

• The average energy associated with each degree of freedom is $\frac{1}{2}{k}_{B}T$.
• For a molecule with $f$ degrees of freedom, the total average internal energy per molecule is $\frac{f}{2}{k}_{B}T$.