What is the packing efficiency of cubic close packing?

Cubic close packing has a packing efficiency of approximately 74.05%, which is one of the highest possible for spheres, equal to hexagonal close packing.

How many atoms are in a face-centered cubic unit cell?

4 atoms. Calculation: 8 corner atoms × (1/8) + 6 face-center atoms × (1/2) = 1 + 3 = 4 atoms.

What's the difference between cubic and hexagonal close packing?

Both have the same packing efficiency (74.05%). The difference is in stacking sequence: CCP follows ABCABC... while HCP follows ABAB.... CCP forms a face-centered cubic unit cell, while HCP forms a hexagonal unit cell.

Vectora

Back to Resources

PRO

This interactive module is part of Founding Pro

You can still read this page for free. Upgrade to unlock full interaction and HD video downloads from the available catalog.

chemistry/cubic-close-packing

View Pricing

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.

Upgrade to Founding Pro to unlock downloads

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

Hexagonal Close Packing

**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

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

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.