Assignment

1. Explain the terms: primitive cell and unit cell.
2. What do you mean by space lattice and what is its characteristic feature?
3. Calculate the number of atoms per unit cell of a metal having lattice parameter 0.29 nm and density 7870 kg/m³. Atomic weight of the metal is 55.85.
4. What do you mean by packing fraction? Calculate the packing fraction for:
   • Simple cubic (SC)
   • Body-centered cubic (BCC)
   • Face-centered cubic (FCC)
5. Why can't an equilateral triangle be used as the basis of a lattice?
6. Is a five-fold axis of rotation compatible with a crystal lattice? If not, why?
7. What is the packing fraction for a hexagonal close-packed (HCP) structure and for the diamond structure?
8. Construct a two-dimensional pentagonal and octagonal lattice. Explain how.
9. What do you mean by coordination number and what is its value for the three cubic lattices (SC, BCC, FCC)?