Question

Number of carbon atoms per unit cell in graphite

Answer 1

if one simply counts all the atoms which are part of a given unit cell. but in crystallography, we usally mean effectice number of atoms per cell. For counting effective number we account for the sharing of corner, edge and face atoms. The corner atoms are shared by 8 unit cells, so each atom contributes 1/8 effective atom to any of those 8 cells. Similarly, edge atoms are shared by 4 cells and hence contribute 1/4 to each cell. Finally, face atoms are shared by 2 cells, so effective number per cell is 1/2.

In this light if you calculate the effective number of atoms per cell you will get

8*(1/8) +4*(1/4)+2*(1/2)+1=4 atoms per cell.

Answer 2

Explanation:

4 carbon atoms

.......... .