Question

Distinguish between face centred and end centred unit cells.

Answer 1

Face centred and end centred unit cells:

	Face centred unit cell	End centred unit cell
1	It contains one constituent particle present at the centre of each face, besides the ones present at its corners	It contains one constituent particle present at the centre of any two opposite faces, besides the ones present at its corners.
2	A face centred unit cell has 4 atoms per unit cell.	An end centred unit cell has 2 atoms per unit cell.
3	Face centred unit cell is present in cubic and orthorhombic crystal systems.	End centred unit cell is present in orthorhombic and monoclinic crystal systems
eg.	Cu, Al, Pt, Au and BaSO4 contain face centred unit cell.	MgSO4.7H2O and Na2SO4. 10H2O contain end centred unit cell.