Consider the formation of a hydrogen bond:
$$\ce{H + H -> H2}$$
The $\Delta H$ is $\pu{-436 kJ mol-1}$, so we can equally write the equation as: $$\ce{H + H -> H2 + \pu{436 kJ}}$$
But depending on the differences in position between the hydrogen atoms, there will be a different force of attractio...
The Periodic Table
The Periodic Table