Step 1: Recall the relation between atomic radius and edge length for FCC lattice.
In face centred cubic (FCC) structure:
\[
a = 2\sqrt{2}\,r
\] Step 2: Substitute the given value of radius.
\[
r = 144.5\ \text{pm}
\]
\[
a = 2\sqrt{2} \times 144.5
\] Step 3: Calculate the edge length.
\[
a = 2.828 \times 144.5 \approx 408.6\ \text{pm}
\] Step 4: Conclusion.
The edge length of the unit cell is 408.6 pm.