Question

Obtain the relationship between density of a substance and the edge length of unit cell.

Answer 1

Consider edge length of cubic unit cell is a, the

∴ Volume of unit cell = a³.

Suppose that mass of one particle is m and that there are n particles per unit cell.

∴ Mass of unit cell = m × n

The density of unit cell (ρ), which is same as density of the sub-substance is given by

Density of Unit Cell = \(\frac{\text{mass of unit cell}}{\text{volume of unit cell}}\)

∴ ρ = \(\frac{m×n}{a^3}\)