Cubic Close Packing
Explore the cubic close-packed structure in metallic crystals. Understand A-B-C layer stacking, the face-centered cubic unit cell, and coordination number.
About this simulation
- What
- An interactive Chemistry simulation of Cubic Close 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 2026-02-15
Key Concepts
Cubic Close Packing (CCP)
Atoms stacked in A-B-C-A-B-C close-packed layers, achieving 74.05% space efficiency.
Coordination Number 12
Each atom has 12 nearest neighbors: 6 in the same layer, 3 above, and 3 below.
Face-Centered Cubic Unit Cell
8 corner atoms (×1/8) + 6 face-center atoms (×1/2) = 4 atoms per unit cell.
Understanding Cubic Close Packing
Cubic Close Packing (CCP) is a fundamental crystal structure adopted by many metals to achieve maximum space efficiency. It is characterized by a packing fraction of 74.05%, the highest possible for identical spheres.
The structure is formed by a repeating A-B-C-A-B-C stacking sequence of close-packed hexagonal layers. This specific layering is geometrically identical to the Face-Centered Cubic (FCC) unit cell lattice.
Our interactive crystal viewer allows you to toggle between internal layers and the fundamental unit cell, demonstrating why metals like gold and silver exhibit a coordination number of 12.
Frequently Asked Questions
Related Simulations
HCP Structure 3D Model
Hexagonal Close Packing (HCP) is a high-efficiency crystal structure with an A-B-A-B stacking sequence. This resource explores the Hexagonal Unit Cell and its 74.05% packing density.
Tetrahedral Voids 3D Interactive
A Tetrahedral Void is the interstitial space surrounded by four atoms in a tetrahedral arrangement. This resource locates the eight tetrahedral voids within a Face-Centered Cubic (FCC) unit cell.
Octahedral Voids 3D Interactive
An Octahedral Void is the interstitial space surrounded by six atoms in an octahedral arrangement. This resource visualizes the position and count of these voids within a Face-Centered Cubic (FCC) lattice.