Question

Li forms a body centered cubic lattice. If the edge length of the lattice is 3.5 × 10⁻¹⁰ m and the observed density is 5.3 × 10² kg m⁻³, calculate the percentage occupancy of lattice points by Li metal.

Answer 1

Theoretical density obtained by 

is with the assumption that each lattice point is occupied by the constituent species. But generally, some lattice points are not occupied by the constituent particles due to some defect in the crystal lattice. These points are called vacancies. The density obtained considering vacancies is called observed density and is surely less than the theoretical density.

Theoretical density