In a body-centred and face-centred arrangement of atoms of an element, what will be the number of atoms present in respective unit cells. Justify your answer with calculation.

Explanation

Body centred cubic : Number of atmos at the corners per unit cell
`=(1)/(8)xx8=1`
Number of atoms present at the centre of the cube = 1
`therefore` Total number of atoms in bcc arrangement
`=1+1=2`
Face centred cubic : Number of atoms present at the corners per unit cell
`=(1)/(8)xx8=1`
Number of atoms present at the faces per unit cell
`=(1)/(2)xx6=3`
`therefore` Total number of atoms in fcc arrangement
`=1+3=4`