The two only species of isolatable, smallest, or unit charges +e and −e present in nature will interact with a polarisable dielectric vacuum through two uniquely defined vacuum potential energy functions. All of the non-composite subatomic particles containing one-unit charges, +e or −e, in terms of the IED model are therefore generated by the unite charges of either sign, of zero rest masses, oscillating in either of the two unique vacuum potential fields. In this paper we give a first principles treatment of the dynamics of a specified charge q in a dielectric vacuum. Based on the solutions for the charge, combined with previous solutions for the radiation fields, we derive the vacuum potential energy function for the specified charge, which is quadratic and consists of quantised potential energy levels. This therefore gives rise to sharply defined charge oscillation frequencies and accordingly sharply-defined masses of the IED particles. By further combining with relevant experimental properties as input information, we determine the IED particles built from the charges +e and −e at their first excited states in the respective vacuum potential wells, togather with their radiation electromagntic waves, to be the proton and the electron, the observationally two only stable (permanently lived) and "free" particles containing one-unit charges. The formation conditions for their antiparticles as produced in pair productions can be accordingly determined. The characteristics of formation conditions of all of the other more energetic non-composite subatomic particles can also be recognised. We finally discuss the energy condition for pair production, which requires two successive energy supplies to (1) first disintegrate the bound pair of vaculeon charges +e, −e composing a vacuuon of the vacuum and (2) impart masses to the disintegrated charges.Part A published at: 2012 J. Phys.: Conf. Ser. 343 012135