(i) What is meant by the term 'coordination number' ? (ii) What is the coordination number of atoms (a) in a cubic close packed structure? (b) in a body–centered cubic structure?

Q. 4.

(i) What is meant by the term 'coordination number' ?

(ii) What is the coordination number of atoms

(a) in a cubic close packed structure?

(b) in a body–centered cubic structure?

Ans.

(i) The coordination number of an atom, ion or molecule is the number of constituent particles which touch that particular atom, atom or molecule.

(ii)

(a) in a cubic close packed structure coordination number is 12

(b) ) in a body–centered cubic structure coordination number is 8.