Question

The crystal lattice and lattice parameters of sodium chloride (NaCl) salt are given below. a = b = c = 2.8 A, a=B=y=90° Atomic radii (in A): Ina -1.80 and rc -1.00 Ionic radii (in A): Na+ = 1.13 and Ta-- 1.67 (a) Identify the lattice points and unit cell of NaCl. (3 marks) (b) Name the Bravais lattice of NaCl. (1 mark) (c) Determine the density (ing cm) of Naci. (3 marks) (d) Determine the atomic packing factor of Naci. (3 marks) Comment and explain the electrical connectivity of NaCl. (2 marks) (1) Based on the molecular-orbital model, explain why nickel metal is a conductor. (4 marks)

Answer 1

Now a since Net accupy a=b=c and so Naci has cubic unit cell. given cr As we know from octahedral void and face centered cubic data occupy that lattice not occupy point so bravais lattice So Nat occupy lattice point octahedral void while ci occupy of unit cell

PAGE NO.: DATE: Assa As we know factor = Nparticle X v paritcle Atomic packing Vunit cell = 4x4 T 83 a3 for fcc 48 = 52a 8 = 529 APF = 4X4 ( F2 a3 TAPE = 0.74

Now a since Net accupy a=b=c and so Naci has cubic unit cell. given cr As we know from octahedral void and face centered cubic data occupy that lattice not occupy point so bravais lattice So Nat occupy lattice point octahedral void while ci occupy of unit cell