Question

The ionic radii of X⁺ and Y⁻ ions are 146 and 216 pm respectively. The probable type of structure shown by it is
(a) CsCl type
(b) Rock salt type
(c) Zinc blend type
(d) CaF₂ type

Answer 1

Answer:

The type of structure is Rock salt type.

Explanation:

The probable type of structure is determined by the radius ratio of cation and anion.

By the radius ratio of cation and anion, it is decided that

Calculating the radius ratio of the cation and anion ionic radii 146 and 216 ppm we get

$\frac{r_+}{r_-} = \frac{146}{218} = 0.669$

With this radius ratio we can conclude that

- The cation is in the Octahyderal void like Na⁺ in NaCl.

- The anion is around the 8 corners.

So this structure is rock salt type.

Answer 2

Answer:

Explanation:

Ratio =    $\frac{ Radii \hspace{.1cm} of\hspace{.1cm} cation }{ Radii \hspace{.1cm} of\hspace{.1cm} anion}$

        =     $x_{c}^+/x_{a}^-$  

         =  $\frac{146}{216}$

         = $0.675$

It is in the range of  $(0.414 - 0.732)$.

Hence, the structure is NaCl type.

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