Reusing Waste Plastic Caps to Build Inexpensive and Easily Changeable Crystal Structure Models

Abstract

An activity of using waste plastic caps and wooden sticks (or steel wires) to construct crystal structures is described. Caps with different colors represent different atoms/ions/interstices, and sticks are employed to carry the caps and describe the positions of atoms/ions/interstices. The cap-and-stick model clearly demonstrates crystal structure characteristics from multiple viewpoints. Students have participated in this activity, and their feedback suggests that the activity is helpful in deepening their comprehensions of lattice structures, unit cells, packing arrangements, distribution and filling of vacancies, and coordinates of atoms/ions/interstices and cultivating hands-on ability and a spirit of teamwork.

Hands-On Experimental Activities on Constructing a 3D Physical Molecular Structure Model Based on Crystal Database Data: Taking the Artemisinin Molecule as an Example

“…that require students to view the structure from a three-dimensional perspective. 16 To help students understand this transformation in teaching, as visualizing the molecular structure with a 3D structural feature is a conventional approach, researchers have designed various creative physical 3D models to simulate the threedimensional structure, such as traditional ball-and-stick type models, 17 different sizes of spheres and rods, 18 latex ball (cuttable) and acrylic resin plates, 19 table tennis balls and tape, 20 magnet-embedded silicone balls, 21 ping-pong balls linked with snap buttons, 22 and plastic caps, 23 which can indeed help students understand the relationship between 2D and 3D model structures, but are not directly helpful in presenting how 3D molecular structures are determined. In the structure determination technique, X-ray crystallography is the most widely used method by far, which can determine atom connectivity and relative and absolute stereochemistry more definitively than other common techniques such as NMR, IR, or GC−MS.…”