Question

For a crystal of sodium chloride, state:
(i) The type of lattice in which it crystallizes.
(ii) The coordination number of each sodium ion and chloride ion in the crystal lattice.
(iii) The number of sodium ions and chloride ions present in a unit cell of sodium chloride.
(iv) The structural arrangement of the sodium chloride crystal.

Answer 1

(i) For a crystal of sodium the type if lattice in which it crystallises is Face Centered Cubic (fcc).
(ii) The co-ordination number of each sodium ion and chloride ion in the crystal lattice is $6:6$.
(iii) The number of sodium ions and chloride ions present in a unit cell is $4$ each.
(iv) The structural arrangement of the sodium chloride crystal is cubic close packing with ${Cl}^{-}$ ions at corners and face centres and ${Na}^{+}$ ions at edge centres and body centre, With respect to ${Na}^{+}$ ion it is octahedral.