chemistry·NCERT Class 12·Solid State
Crystal Unit Cells
Medium+80 XP💎
NaCl has the face-centred cubic structure — every Na⁺ is surrounded by 6 Cl⁻ ions. How many atoms actually 'belong' to one unit cell? Rotate and count.
›SCC: 8 corners × 1/8 = 1 atom; coordination number 6; packing 52%.
›BCC: 8×1/8 + 1 = 2 atoms; coordination number 8; packing 68%.