At the last step, we make the assumption that both chains are identical in length N , except have opposite charge valency. This result is a straightforward modification of the result from the Debye-Hückel expression in Equation , and justifies the diagrams we indicated earlier -each Ψ-bond contributes a factor ψ, and each orange ω-bond contributes a factor N g D . We note that the factors of N α in the prefactor are important, as they convert the number density of chains, ρ i to number densities of monomers. The factors N g D account for connectivity of ideal, Gaussian coils, and simplify to factors of unity as N → 1. The next ring diagram is again similar: