Question

Sodium crystallieses in abody centerd cubic lattice with a unit edge of $4.29$ A . The radius of sodium atom is approximately.

Answer 1

In BCC lattice,atoms touch along the body diagonal of the cube. Thus,

$4r=\sqrt{3a}$

$r=\frac{\sqrt{3a}}{4}$ where $a=4.29\dot{A}$

$r=1.86\dot{A}$