By substituting the above value of Z back into E b, one obtains the binding energy as a function of the atomic weight, E b (A). Maximizing E b (A)/ A with respect to A gives the nucleus which is most strongly bound, i.e. most stable. The value we get is A = 63 (copper), close to the measured values of A = 62 (nickel) and A = 58 (iron).