a = 2r Where a = Edge length or side of the cube r = radius of each particle, The volume of the cubic unit cell = a3 =( 2r) 3 = 8r 3
A simple cubic unit cell contains only 1 atom. The volume of the occupied space = 4 / 3 Π r 3
Packing efficiency =( Volume of one atom X 100)/( Volume of cubic unit cell)
Therefore it can be concluded that ccp and hcp has maximum packing efficiency.
Calculations Involving Unit Cell Dimensions
Edge length of a unit cell of a cubic crystal = a,
Density of the solid substance = d Molar mass = M Volume of a unit cell = a3
Mass of the unit cell = number of atoms in unit cell × mass of each atom = number of atoms present in one unit cell( z) × mass of a single atom( m)