Electrical resistance?

Question

If electric conduction involves electrons repelling outer shell electrons out of their shells and onto the next atom to repeat the process, why are some atoms more conductive than others?. Are the valence electrons easier to displace?

Answer 1

Yes, that is true at an atomic level.  At a material level, a material has a characteristic resistivity (greek letter rho) which is a measure of how easy/difficult it is to displace those electrons in that material.  The resistivity can also be defined as E/J where E = magnitude of Electric Field and J = magnitude of Current Density

Answer 2

Yes some atoms/molecules hold onto their electrons better than others.