1. The problem statement, all variables and given/known data the volume density of a body centered cubic lattice is 5.3*10^22 Calculate the lattice constant, effective radius of atom, surface density on 110 plane, and distance between two nearest parallel 110 planes. 2. Relevant equations 4/a^3= volume density 2/sqrt2*a^2 3. The attempt at a solution 5.3*10^22=4/a^3, a=4.25 A 2) effective atom radius, I know its( r1+r2) but I do not know what factor its multiplied by(i.e. 4*(r1+r2)/sqrt3, 2...) and I think I could solve for r^2 instead of r1 and r2. 3) 2/(sqrt2*(4.25*10^-8)^2) = surface density? 4) I do not know how to find distance between planes, is this r*2 ?