I'm still a bit flummoxed over the concept of positive and negative charges in the elementary particles known to us - they seem to maintain a mass-containing 'state'. It's not the elementary particle's qualities themselves that has me thinking, but rather their reaction to each other.
If one takes one of our most basic elementary particles, the quark, one can see that it never remains in an independent state for any length of time, but rather is absorbed by another element, or combines with other 'free' quarks to create a Hadron (Neutron or Proton).
When one examines the grouping of Hadrons, one can see that they either contain two 'up' quarks (+2/3 charge) and one 'down' quark (-1/3 charge) as a Proton, or the opposite (two 'down' quarks and one 'up' quark) as a Neutron. First off, one notices that the higher the charge, the less the mass - Protons have half the mass of Neutrons. Examined individually, we see that the combined charge of each element 'balances' into two different states (a Proton = (+2/3) + (+2/3) + (-1/3) = or a charge of 1; a Neutron = (+2/3) + (-1/3) + (-1/3) = or a charge of 0). The 'binding force' between oppositely-charged quarks is probably generated by each element's effort to annihilate each other, or 'draw' from its neighbouring quark's opposing charge, but lacking the power to do so (the elements must have the same opposing charge to annihilate each other), they simply bind. If the charges of two elementary particles are not equal, I am persuaded that the 'binding force' is generated by the 'overlap' between the charges - the 'up' quark would 'suck' an excess 1/3 charge beyond the charge of a neighbouring 'down' quark, and the -1/3 'down' quark can only 'suck' 1/3 of the charge of a neighbouring 'up' quark (if the two could annihilate each other, a +1/3 charge quark (inexistent in our universe) and a -1/3 quark ('down' quark) would remain). So two 'similar' quarks are in an eternal inter-annihilation battle, but it takes three to attain the balanced 'states' we know as Neutrons and Protons.
Moving one step further, a positively-charged Proton (+1 charge) attracts a negatively-charged electron (-1 charge), which would result in an atom (hydrogen) that has a 0 charge through the sum of its parts. The most common Helium atom (2 protons, 2 neutrons, 2 electrons) would have a sum charge of 0 also (six 'up' quarks, six 'down' quarks, two electrons). The most stable form of Lithium atom (7L) has 3 protons, 4 neutrons, and 3 electrons resulting in an overall charge of 0... but it is in itself an unstable element (because of the ten 'up' quarks (+6 2/3 charge) fighting 11 'down' quarks (-3 2/3 charge))? It would be interesting to follow this up the periodic table.
Questions remaining: above I have reflected upon the behaviour of the most common quark 'flavours', but there exist quarks with higher mass than 'up' and 'down' quarks: 'charm' and 'top' quarks are identical to 'up' quarks in their charge and spin, but they have much greater mass - could this be a difference in the volume of 'neutral state matter' affected by a charge? Also, what of the 'spin' of elementary particles? All save Bosons (energies - eg. Photons) have spin. Could it be possible that a spin put on 'neutral state matter' is enough to transform it into a different (but 'neutral charge') discernible element (a neutrino) having some mass?
The constant I see through all the above is a 'state of balance' - elementary particles of all sorts seem be trying to attain a 'level of zero' state (with or without charge). Only elements with opposing factors can annihilate each other (the opposing 'spins' of neutrinos/antineutrinos cancel each other, the opposing charge of hydrogen and anti-hydrogen atoms cancel each other (leaving neutrinos, if their spin is in the same direction?)).