π Crystal Structures
Rotate and explore the six fundamental crystal lattice types in 3D. See how atoms pack together in Simple Cubic, BCC, FCC, HCP, Diamond, and NaCl structures. Drag to rotate. Observe coordination numbers, packing efficiency, and unit cell geometry.
Click and drag to rotate Β· Scroll to zoom
Body-Centred Cubic (BCC)
BCC has atoms at all 8 corners of the cube plus one in the centre. Each atom touches 8 neighbours along the body diagonal. Coordination number = 8. Packing efficiency 68%. Common in metals: iron (Ξ±-Fe), tungsten, chromium, molybdenum. Less dense than FCC.
Comparing Crystal Structures
Simple Cubic (SC) β Atoms
only at cube corners. CN = 6. Packing 52%. Rare β only Polonium
adopts this structure.
BCC β Atoms at corners +
body centre. CN = 8. Packing 68%. Typical in Group 5/6 metals and
iron below 912Β°C.
FCC β Atoms at corners + all
face centres. CN = 12. Packing 74% (highest for equal spheres). Al,
Cu, Ni, Au, Ag.
HCP β Hexagonally
close-packed. CN = 12, packing 74% β same density as FCC but
different stacking (ABAB vs ABCABC). Mg, Ti, Zn, Co.
Diamond Cubic β FCC with
basis: 2 atoms per lattice point (tetrahedral bonding, spΒ³). CN = 4.
Packing only 34% but extremely rigid. Carbon, Si, Ge.
NaCl (Rock Salt) β Two
interpenetrating FCC sub-lattices (NaβΊ and Clβ»). Each ion surrounded
by 6 of the opposite type. CN = 6. Very common for ionic compounds.