Lattice constant, space between planes?

[orangeincup]

Homework Statement

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.

Homework Equations

4/a^3= volume density
2/sqrt2*a^2

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 ?

 

[nasu]

For 2, you need to know the positions of two nearest neighbors. If you take an atom in the corner, where is its nearest neighbor?
For 3, what is a 110 plane for a cubic lattice? Can you draw it?
You can calculate the distance between planes either from geometry or by using the magnitude of the reciprocal lattice vector with the same indices.