This tutorial will introduce students to some of the three-dimensional crystal structures exhibited by ionic and metallic solids. They will examine the simple cubic, body-centered cubic, face-centered cubic, and the hexagonal closest-packed systems. To facilitate visualization of the structures at the atomic level, they will use the Crystal Explorer website at Purdue University.
After completing this tutorial, students will be able to:
- Identify and describe basic crystal structures from their unit cells.
- Describe the relationship between crystal packing and unit cell.
- Determine whether atoms/ions in a crystal structure are closest packed.
- Locate tetrahedral, octahedral, and cubic holes in a unit cell.
- Apply geometric relationships to determine the length of a unit cell edge in terms of the radii of its atoms/ions.
- Determine the coordination number of an atom/ion in a crystal structure.
The Crystal Explorer website is a free resource that contains all of the images needed to complete this tutorial.
When I teach my foundations-level inorganic chemistry class, I have students use Ludwig Mayer’s Solid State Structures JCE Software to complete this tutorial; however, the software is no longer commercially available. It utilizes the PCMolecule application which I am still able to access on newer computers by adjusting the compatibility settings. The images in the software use the same color schemes as the structures in the Solid State Model Kit. See Teacher Notes for further information. I don’t have students use the model kits, though I do assemble one or two structures for them refer to if they need.
Students can complete the tutorial in one lab session or in multiple lecture sessions. I currently use one lecture session to get them started and have them complete it outside of class as a homework assignment.