Implicit in the Mulliken definition of electronegativity is the ability to relate energy to the movement of charge within a molecule. As one of the simplest and very studied reactions, the role of charge movement associated with the proton affinity was examined. The reformulation of electronegativity by Reed permits facile computation of both the atomic charges and the energy required to create them. The latter is called the atomic charging energy. The relationships between the proton affinity and atomic charge and with the transfer of charge are examined. Through the relationship between proton affinity and the atomic charging energy, a relationship between proton affinity and molecular structure is developed.