Simple Cubic Packing
Explore the simplest crystal packing structure. Understand AA-layer stacking, the 1/8 corner atom trick, and why only Polonium uses this arrangement.
About this simulation
- What
- An interactive Chemistry simulation of Simple Cubic Packing.
- Who
- Designed for AP, IB, and A‑Level Chemistry students.
- How
- Runs in any modern browser — drag, adjust, and explore in real time.
Updated 2026-03-25
Key Concepts
AA-AAA Layer Stacking
Atoms stack directly on top of each other with no offset between layers, creating the simplest possible 3D arrangement.
Coordination Number 6
Each atom touches exactly 6 neighbors: one above, one below, and four in the same plane.
1/8 Corner Atom Rule
Each corner atom is shared by 8 unit cells, contributing only 1/8 to each. Total: 8 × 1/8 = 1 atom per unit cell.
Understanding Simple Cubic Packing
Simple Cubic Packing (SC) is the most fundamental crystal packing arrangement. Atoms are positioned at the eight corners of a cube, creating an open, highly symmetrical structure with the lowest packing efficiency among common crystal types.
The structure follows an AA-AAA stacking sequence — each layer sits directly on top of the previous one with zero offset. This results in a coordination number of 6 and a packing efficiency of only 52.4%.
Despite its simplicity, SC packing is extremely rare in nature. Only Polonium (Po) crystallizes in this form at standard conditions, because the large voids make it energetically unfavorable compared to denser arrangements.