[Olympiad] Chromium crystallizes in a body-centered cubic (BCC) lattice. If the atomic radius of Cr is 125 pm, what is the length of the unit cell edge?
- 250.0 pm
- 288.7 pm
- 353.5 pm
- 433.0 pm
📝 Detailed explanation
In BCC, the atoms touch along the body diagonal. √3 * a = 4r.a = 4r / √3 = 4 * 125 / 1.732 = 500 / 1.732 = 288.67 pm.