Question

The coordination number for a ccp lattice is :

Answer 1

The third layer isn’t aligned with either first or second layer.
Fourth layer, above third layer, repeats first layer's orientation.
Thus, the lattice has ABCABC.. type of packing.


For ccp/fcc structure, the number of nearest neighbors of a particle is 12 as shown.
Such structure is called cubic close packing(ccp) or face-centred cubic (fcc) structure.
$\text{Examples :}Ca,Sr,Ag,AuandCu$