Question

Aluminium crystallises in an $fcc$ structure. Atomic radius of the metal is 125 pm. Calculate the edge length of unit cell of the metal?

Answer 1

For the fcc structure, let us consider a is the edge of the cube and r is the radius of atom.

Given that r is equals to $125$ pm,

$a=2\sqrt{2}r$

$a=2\times 1.414\times 125pm\approx 354pm$

So, the the edge length of unit cell of the metal is $354$ pm.