1. The problem statement, all variables and given/known data 2. Relevant equations Please see below. 3. The attempt at a solution From my thread in the Solid State section (and input from DrDu): The Thomas-Fermi wavevector relates to the damping of an electric field caused by build up of carriers around an impurity (screening). Where, ##2\pi/k_0## is the characteristic length over which a static perturbation is screened in a metal. The trouble I'm having with this question is that I dont understand how to use the valance band shell information, please could someone explain to me how the information may be used to determine resistivity. Thanks for any help.