A freely jointed chain of N monomers performs a random walk. The end-to-end distance scales as R ~ N^ν, with ν=1/2 (ideal) or ν≈0.588 (self-avoiding in 3D).
⟨R²⟩ = N·b² (ideal FJC) | ν = 0.588 (SAW, Flory) | Persistence length lp = b/(1-cos θ)