NaCl and CsCl have similar formular . Then why they have differnet strutures ?

Explanation

The radius ratio of NaCl ` (r_(Na+)// r_(Cr-)) ` lies in the range 0.414 - 0.732 . Hence, is has coordination number of 6. i.e.c octahedral arrangement. On the other hand, the radius ratio of CsCl `(r_(cs^(+) //r^(cl-))` lies in the ranhge 0.732 -1 .0 Hence, it has a coordination number of 8. i,e. it has a body -centred cubic arrangement.