1. The problem statement, all variables and given/known data In xenon (Z = 54), what is the effective charge Zeff experienced by an electron in the M (n=3) shell? 2. Relevant equations Zeff = Z - total electrons in K and L shells 3. The attempt at a solution I think total electrons in K shell are 8 and in L shell are 18 then Zeff = 54-26 = 28 but I got wrong.. please help me..