Hexagonal Close Packing
Explore the hexagonal close-packed structure in metallic crystals. Understand A-B layer stacking, the hexagonal unit cell, and coordination number.
About this simulation
- What
- An interactive Chemistry simulation of Hexagonal 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 2026-02-14
Key Concepts
Hexagonal Close Packing (HCP)
Atoms stacked in A-B-A-B 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.
Hexagonal Unit Cell
A primitive hexagonal prism containing 6 atoms (2 formula units).
Understanding Hexagonal Close Packing
Hexagonal Close Packing (HCP) is a dense atomic arrangement where atoms occupy 74.05% of the total volume, shared by metals such as Magnesium (Mg), Zinc (Zn), and Titanium (Ti).
The structure is characterized by an alternating A-B-A-B stacking sequence of close-packed hexagonal layers, where atoms in the third layer are positioned directly above the atoms in the first layer.
Our interactive crystal viewer demonstrates the coordination number of 12 and visualizes the geometric relationship between the hexagonal close-packed layers and the primitive hexagonal prism unit cell.
Frequently Asked Questions
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