Information • Textbooks • Media • Resources edited by
JCE Software
Jon L. Holmes Nancy S. Gettys
Dynamic Visualization in Chemistry
University of Wisconsin–Madison Madison, WI 53706
Abstract of Special Issue 31, a CD-ROM for Mac OS and Windows James P. Birk,* Debra E. Leedy, Rachel A. Morgan, Mark Drake, Fiona Lihs, Eleisha J. Nickoles, and Michael J. McKelvy Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604; *
[email protected] What happens to the atoms or molecules of a substance when it undergoes a chemical or physical change? How are the changes in matter that you see in the laboratory (or in everyday life!) related to the theoretical models taught in chemistry class? Understanding chemistry involves being able to answer these questions. For students taking their first chemistry course, it is particularly important that this information be conveyed as clearly and concisely as possible. Dynamic Visualization in Chemistry consists of four multimedia presentations. •
Reaction of Galena with Acid
•
Intermetallic Compound Formation
•
Sublimation of Ice
•
Intercalation
Each is designed to help chemistry students acquire a dynamic, three-dimensional, atomic-level visualization of matter and to use this view to explain and ultimately predict the behavior of materials. It integrates video of experiments and animations of theoretical models. Students “zoom in” on physical and chemical processes at resolutions as high as the atomic level. Exciting research instruments (scanning tunneling microscope and scanning and transmission electron microscope) image phenomena and introduce students to the cutting edge of science and technology. Graphic images produced using these instruments, combined with bench-top demonstrations and computer animations, provide a unique visual teaching tool. Such visualization will give students a better fundamental understanding of chemical reactivity. Reaction of Galena with Acid A series of photographs of a galena (PbS) crystal at increasingly higher magnifications is presented to provide
perspective. These are followed by a series of videos of the reaction of galena with acid—first at the macroscopic level, then viewed through an optical microscope, and finally viewed with a scanning tunneling microscope. A computer animation displays a proposed mechanism for the reaction based on the evidence from the videos. This module is designed for use in conjunction with lecture material on double-displacement reactions. It can also be used as a follow-up tool for students to explore outside of the classroom. The goal is to help students understand the process of the reaction from the macroscopic level to the microscopic level. New aspects of the reaction are revealed at each level. Animation adds details and helps the microscopic images make sense. Intermetallic Compound Formation A macroscopic-scale video of the synthesis of NiAl alloy establishes that one metal can react vigorously with another. A view of the mixed reactants and the product of this reaction as seen through an optical microscope provides additional information. Real-time video of the synthesis of Au3In alloy formation observed by a transmission electron microscope follows. A computer animation shows a proposed mechanism for the Au3In alloy formation. For more advanced students, graphics and computer animations explore the details (unit cells and layering sequences) of the two structures of the Au3In alloy. This module can be used to augment discussions of stoichiometry, law of conservation of mass, physical and chemical changes in reactions, types of reactions, and solidstate structures. It can also be used as a follow-up tool for students to explore these concepts outside of class. Its goal is to encourage students to think about the particulate nature of matter.
Figure 1. Images from Reaction of Galena with Acid. From left, galena (PbS) reacts with acid in a test tube; reaction of galena with acid under an optical microscope; the galena surface reacting with acid viewed with a scanning tunneling microscope; computer animation of a proposed mechanism for the reaction.
JChemEd.chem.wisc.edu • Vol. 80 No. 9 September 2003 • Journal of Chemical Education
1095
Information • Textbooks • Media • Resources Figure 2. Image from Sublimation of Ice. This photograph shows a single hexagonal ice crystal under a scanning electron microscope. The white bar in the lower right corner is 0.5 mm long.
Sublimation of Ice A video of the sublimation of iodine provides a clearly visible macroscopic view of sublimation. A series of images of ice crystals at increasing magnification follow, obtained using an optical microscope, scanning electron microscope, and transmission electron microscope. Then, real-time video obtained by transmission electron microscopy shows the surface of an ice crystal as water molecules escape to form water vapor. Two computer animations depict the mechanism of sublimation. A phase diagram for water with linked graphics illustrating water molecules in the gas and liquid phases and illustrating the ten phases of ice is provided. Computer animations show rotation of all ten crystal structures of ice. The focus of this module is the sublimation of ice and its primary use is in discussion of phases of matter. It can also be used as an anticipatory exercise leading into the concepts of hydrogen bonding and intermolecular forces. It is applicable to the kinetic theory of molecular motion, and, at higher levels, crystal structures, space groups, symmetry elements, and electron diffraction theory. The module can help students reinforce basic concepts and allow them to examine higher-level concepts at their own rate. Intercalation This module focuses on the intercalation of ammonia or hydrazine into the layered structure of tantalum disulfide. It includes animations, video of the reaction at the macroscopic level, microscopic level (both a powdered sample and single crystal), and two videos of the reaction under different conditions as viewed with a transmission electron microscope. Animations of a series of models for the reaction based on the observation of the videos are provided. This module could be used in a discussion of the scientific method, as well as in discussing the particulate
Figure 3. Image from Intercalation. The dark areas are the tantalum disulfide host layers, and the light lines between the host layers are the spaces filled by guest ammonia molecules.
nature of matter and solid-state structures. Models are developed from experimental evidence and then modified as more experimental evidence is observed. A menu-driven format allows the evidence and the models to be revealed in a step-wise fashion, leading to discussion at each stage. The module could also be used to discuss the development of reaction mechanisms. Development and Design Video clips were collected with a camera and an electron microscope or an optical microscope and then digitized. Images from the scanning tunneling microscope were provided by Robert Hamers and Steve Higgens, Department of Chemistry, University of Wisconsin–Madison. Dynamic Visualization in Chemistry is intended for general chemistry students, but can easily be adapted and used in high school Advanced Placement chemistry courses. Written documentation provides information about where in the introductory chemistry curriculum each module can be used and lists discussion questions to be used with the presentation. With the inclusion of upper level concepts, such as phases of ice, Dynamic Visualization in Chemistry can also be used in sophomore to senior inorganic chemistry. Acknowledgments This material is based on work partially supported by the National Science Foundation under grants DUE 9555098 (Dynamic Visualization) and DUE 9453610 (Arizona Collaborative for Excellence in the Preparation of Teachers), and the U.S. Department of Education under grant OPE P336B990064 (Arizona Teacher Education Collaborative). Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the National Science Foundation or the Department of Education. Prices and Ordering Information The price for this CD-ROM for Macintosh and Windows for a single user on a single machine is $75 U.S./$95 non-U.S.; LANs (up to 12 users): $300 U.S./$320 non-U.S. Prices for libraries and wide area networks or other information may be obtained by contacting JCE Software, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI 53706-1396; phone; 608/262-5153 or 800/ 991-5534; fax: 608/265-8094; email:
[email protected]. An order form is inserted in this issue that provides prices and other ordering information. Information about all JCE publications (including abstracts, descriptions, updates) is available from our World Wide Web site at
http://jchemed.chem.wisc.edu/JCESoft/ Hardware and Software Required
1096
Computer
CPU
Mac OS Compatible
Pow e rPC ; ≥ 150M H z re comme nde d
Windows Compatible
Pe nt ium; ≥ 150M H z re comme nde d
RAM
Drives
Graphics
System
Other Software
≥ 64 M B
≥ 4 × C D-ROM ; H ard dis k
≥ 800 × 600; t hous ands or millions of colors
M ac OS 8.6 or highe r
Quick T ime 6
≥ 64 M B
≥ 4 × C D-ROM ; H ard dis k
≥ 800 × 600; 16-bit or 24-bit color
W indow s X P, 2000, M E, 98
Quick T ime 6
Journal of Chemical Education • Vol. 80 No. 9 September 2003 • JChemEd.chem.wisc.edu
