Q. The radius ratio in $ CsCl $ is $ 0.93 $ . The expected lattice structure is
UPSEEUPSEE 2008
Solution:
The ratio of the radius of the cation to the radius of the anion is called radius ratio. From this ratio the structrue of lattice can be determined by using the following table
$r_{c}/r_{a}$
Arrangement
$0.155-0.225$ $\,$
Planar triangular $\,$
$0.225-0.414$ $\,$
tetrahedral
$0.414-0.732$ $\,$
Octahedral $\,$
$0.732-1.0$ $\,$
Body centred cubic $\,$
Here, the radius ratio of $CsCl$ is $0.93$, hence its lattice structure is body-centred cubic
| $r_{c}/r_{a}$ | Arrangement | |
|---|---|---|
| $0.155-0.225$ $\,$ | Planar triangular $\,$ | |
| $0.225-0.414$ $\,$ | tetrahedral | |
| $0.414-0.732$ $\,$ | Octahedral $\,$ | |
| $0.732-1.0$ $\,$ | Body centred cubic $\,$ |