Question

Iron occurs as body centered as well as face centered cubic unit cell. If the effective radius of an atom of iron is 124 pm, compute the density of iron in both these structures.

Answer 1

(i) For body−centered cubic unit cell (BCC), 

As √3 a = 4r for a BCC lattice, the volume of unit cell = a³ 

(ii) For face−centered cubic unit cell (FCC),

As, √2 a = 4r for a FCC lattice, the volume of unit cell = a³