Derive the formula for the density of a crystal whose length of the edge of the unit cell is known?
Let the edge of the unit cell = a pm Number of atoms present per unit cell = Z The atomic mass of the element is represented as = M So, the volume of the unit cell = (a pm)3(a pm)3 = a3 x 10-30cm3a3 x 10-30cm3 Density = MassVolumeMassVolume Mass of unit cell can be calculated as = Z x m Where m is the mass of each atom = Atomic massAvogadro ′ s number=MN0Atomic massAvogadro ′ s number=MN0 Now, putting all the values, we can write: Density=Z × M/a3 × N0 × 10-30g/cm3
