An elemental crystal has a density of 8570kg/m3. The packing efficiency is 0.68. The closest distance of approach between neighbouring atom is 2.86?. What is the mass of one atom approximately?
The packing efficiency =0.68, means the given lattice is BCC. The closest distance of approach =2r 2r=2.86?=a3 or a=32×2.86=3.30? Let atomic weight of the element =a ∴36×1023×(3.3)3×10−242×9=8.57 a=8.57×3×(3.3)3×0.1 =92.39≃93 amu