Question

Sodium crystallises in a body centeredcubic unit cell (bcc) with edge length 4.29 A^o. What is the radius of the sodium atoms ? What is the length of the body diagonal of the unit cell ?

Answer 1

$$\begin{gathered} Forbcc \\ radius=\frac{\sqrt{3}}{4}a \\ =\frac{\sqrt{3}}{4}\times 4.29\times {10}^{-10}(1A^0={10}^{-10}m) \\ =1.858\times {10}^{-10}m \\ Bodydiagonalofbcc=4r \\ =4\times 1.858\times {10}^{-10} \\ =7.430\times {10}^{-10}m \end{gathered}$$