A primitive cubic unit cell has a simple cubic structure with one atom present in each of the eight corners of the cube. In addition each atom is shared equally by eight other cubes such that there is atom per unit cell.
The edge length (a) of a simple cube is related to the atomic radius (R) by the relation:
a = 2*R
For the Ga unit cell a = 362 pm
Therefore, R = a/2 = 362/2 = 181 pm
Thus, the radius of Gallium atom is 181 pm
