Copper crystallises in an FCC lattice with a unit cell edge length of . The radius of a copper atom — Solid State Chemistry Question

💡 Solution & Explanation

In a face-centred cubic (FCC) unit cell, atoms touch each other along the face diagonal. The relationship between edge length ($a$) and atomic radius ($r$) is $\sqrt{2}a = 4r$. Thus, $r = \frac{\sqrt{2} \times 361}{4} = \frac{361}{2\sqrt{2}} \approx 127.6\text{ pm} \approx 128\text{ pm}$.