Groups of 3-4 students follow this handout to create models of the 7 crystal systems and the 14 Bravais lattices using DOTS gumdrops, bamboo skewers and wood toothpicks.
After completing this exercise, a student should be able to:
distinguish between the seven crystal systems
distinguish between primitive, body-centered, face-centered, and base-centered lattices
from a set of unit cell parameters, identify possible crystal systems
from space-group notation, identify a crystal as primitive, body-centered, face-centered, or base-centered
For one group creating 14 models:
Three 7.5 oz boxes of DOTS gumdrops (Tootsie Roll Industries, LLC)
Three packages of wood sticks in three different sizes: any combination of 12", 10", 6", or 4" bamboo skewers and/or 2 5/8" toothpicks
The activity is conducted during a single, 75-minute lecture period. Students documented their models with photographs and submitted the actual models in at the end of the class period.
It is used in conjunction with the Solid-State Model Kit sold by the Institute for Chemical Education - half of the class works with the ICE Solid-State Kit while the other half builds these models, and at the next class period the groups switch activities.
This activity is a skill-building exercise to prepare students for one requirement of a multifaceted term project: the description of the unit cell of a mineral structure in an oral presentation and term paper.