Q- Distinguish between:
(i) Hexagonal and monoclinic unit cell
(ii) Face-centred and end-centred unit cell
Answer- (i) Difference between Hexagonal unit cell and monoclinic unit cell is given below:
| Hexagonal Unit Cells | Monoclinic Unit Cells | |
| 1. | It has a Hexagonal crystal system | It has a Monoclinic crystal system |
| 2. | No parallelogram structure is present in it. | The base of the unit cell has a parallelogram structure |
| 3. | Two Axes are equal and the third one is unequal (a=b≠c). | All the Axes are unequal (a≠b≠c). |
| 4. | In α= 90°, β= 90° and γ = 120° | In α= 90°, β≠ 90° and γ = 90° |
(ii) Difference between Face-centred Unit Cells and End-centred Unit Cells is as follows:
| Face-centred Unit Cells | End-centred Unit Cells | |
| 1. | The constituent particles in Face-centred Unit Cells are present at the corners and one is present at the center of each face. | The constituent particles in End-centred Unit Cells are present at the corners and one is present at the center of opposite corners. |
| 2. | Four faces are present in Face-centred Unit Cells | Two faces are present in End-centred Unit Cells |
| 3. | Face-centred Unit Cells are present only in orthorhombic and cubic crystal systems. | End-centred Unit Cells are present only in Monoclinic and orthorhombic crystal systems. |
| 4. | Examples- Al, Pt, Cu, Au, etc. | Examples- Na2SO4. 10H2O, MgSO4.7H2O, etc. |
Class 12th Important Questions
- Give the significance of a lattice point
- Name the parameters that characterise a unit cell
- Ionic Solids Conduct Electricity in Molten State but not in Solid state. Explain
Tag- Distinguish between Hexagonal and monoclinic unit cell face centred and end centred unit cell