Free interactive chemistry · SIM-CRYS-001
Unit cell builder
Build unit cells in 3D: count atoms, see voids, and calculate packing and density.
Open the interactive simulation →How to use this simulation
- Choose “Metal cells” or “Ionic structures”, then a cell type.
- Turn on “Cut atoms at the cell faces” to see only the part inside the cell.
- Turn on “Show voids” to see tetrahedral (green) and octahedral (red) holes.
- Read Z, coordination number, packing efficiency and density.
What to notice
- Corner atoms count 1/8, face atoms 1/2, edge atoms 1/4.
- FCC and hcp fill 74% of space; BCC 68%; simple cubic 52%.
Try this
Count Z for FCC yourself from the cut view before reading the answer.
Try it for free →