Question

In which of the following structures coordination number for cations and anions in the packed structure will be same ?

(a) $C{l}^{-}$ ions form fcc lattice and $N{a}^{+}$ ions occupy all octahedral voids of the unit cell

(b) $C{a}^{2+}$ ions form fcc lattice and $F^{-}$ ions occupy all the eight tetrahedral voids of the unit cell

(c) $O^{2-}$ ions form fcc lattice and $N{a}^{+}$ ions occupy all the eight tetrahedral voids of

(d) $S^{2-}$ ions form fcc lattice and $Z{n}^{2+}$ ions go into alternate tetrahedral voids of the unit cell

Answer 1

Answer: (a) $C{l}^{-}$ ions form fcc lattice and $N{a}^{+}$ ions occupy all octahedral voids of the unit cell

$NaCl$ crystal has rock salt structure having fcc lattice in which $C{l}^{-}$ ions are present at fcc lattice points and face centre and $N{a}^{+}$ occupies all the octahedral void of given unit cell.

Where. Coordination number of $N{a}^{+}=6$

Coordination number of $C{l}^{-}=6$