Question

Coordination numbers of $C{s}^{+}$ and $C{l}^{-}$ in $CsCl$ crystal are :

• A. $8,8$
• B. $4,4$
• C. $6,6$
• D. $8,4$

Answer 1

The correct option is A $8,8$

The coordination number is the number of ions that immediately surround an ion of the opposite charge within a crystal lattice.

The formula unit for cesium chloride is $CsCl$, also a 1:1 ratio.

The center ion is the ${Cs}^{+}$ ion and is surrounded by the eight ${Cl}^{-}$ ions at the corners of the cube.

Each ${Cl}^{-}$ ion is also surrounded by eight ${Cs}^{+}$ ions. The coordination numbers in this type of crystal are both $8$.

CsCl and NaCl do not adopt identical crystal packing arrangements because the ${Cs}^{+}$ ion is considerably larger than the ${Cs}^{+}$ ion.

Therefore, the correct option is A.