Question

A compound has rocksalt structure. what is the coordination no. of A and B? How many atoms of A and B are associated with each unit cell?​

Answer 1

Answer:

Rock salt is NaCl.

The coordination number in crystal structure of NaCl is 6 : 6.

It means each Na+ is surrounded by 6 Cl- and each Cl- is surrounded by 6 Na+ .

The ccp lattice is formed by chloride ions i.e. Cl- occupy all corners (8 * 1/8) and face centers (2 * 1/6).

So, there are 4 chloride ions.

Na+ occupy all octahedral sites.

In ccp lattice, there are 4 octahedral sites.

So, number of Na+ = number of Cl- = 4