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JCE WebWare: Web-Based Learning Aids
William F. Coleman Wellesley College Wellesley, MA 02481
Peer-Reviewed JCE WebWare
Edward W. Fedosky University of Wisconsin–Madison Madison, WI 53715
A Lattice Energy Spreadsheet is a tool that easily calculates lattice energies. It also illustrates the relation between crystal structure, coordination number, and ionic radii. A Lattice Energy Spreadsheet contains five related worksheets: Lattice Energy, MX Structure Map, Kapustinsky Lattice Energy, Directions, and Discussion, each described below.
In the Lattice Energy worksheet, the lattice energy of many binary compounds can be calculated in about a dozen mouse clicks. An element is selected, and the radius corresponding to the desired charge and coordination number is selected. The same is done for the counter ion, and the anticipated crystal structure of the compound is chosen (rock salt, wurtzite, etc.). The lattice energy is then calculated. This sheet uses enthalpies of formation of monatomic gaseous atoms from the elements, ⌬H⬚form to calculate lattice energies. The results are more accurate than the values obtained by simply summing enthalpies of fusion and vaporization. The results of the corresponding Born–Haber cycle are also graphed on this sheet. A structure map is a plot of average principal quantum number versus difference in electronegativity. Compounds in the same region of such a plot tend to have the same type of crystal structure. In MX Structure Map, students or instructors select two elements making up a 1:1 compound. The spreadsheet locates the chosen compound on the structure map, allowing the compound’s structure to be predicted. The Kapustinsky Lattice Energy worksheet has thermochemical radii of hundreds of anions and cations. Just select a compound’s anion and cation from a drop-down list, and the compound’s lattice energy, including estimated uncertainty, is calculated with the Kapustinsky equation! In the Directions worksheet, users find complete instructions and suggestions for using this spreadsheet, along with references to excellent Web sites on crystal structures. Discussion discusses the sources of much of the data used in the calculations and provides more details about how the calculations are made. Try this spreadsheet for yourself first; then use it in a presentation in your next inorganic chemistry course!
Born–Haber cycle plot for TiO from A Lattice Energy Spreadsheet.
An MX structure map from A Lattice Energy Spreadsheet.
This month we add another in a series of interactive spreadsheets to the peer-reviewed collection of JCE WebWare. Using A Lattice Energy Spreadsheet, instructors and students can easily calculate crystal lattice energies of many binary compounds. A Lattice Energy Spreadsheet also generates a plot of the corresponding Born–Haber cycle, and can help you and your students predict what crystal structure the compound might have. A Lattice Energy Spreadsheet is a great tool for individual use or for classroom presentations in an inorganic chemistry course. Use it along with other excellent spreadsheets you can find in the peer-reviewed and open review collections of JCE WebWare at http://www.JCE.DivCHED.org/JCEDLib/ WebWare/.
A Lattice Energy Spreadsheet by Christopher King, Department of Chemistry, Troy University, Troy, AL 36082 Keywords: Computer-Based Learning; Crystals/Crystallography; Inorganic Chemistry; Multimedia-Based Learning; Thermodynamics; Upper-Division Undergraduate Requires: Web browser and Microsoft Excel
1584
Journal of Chemical Education
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Vol. 82 No. 10 October 2005
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www.JCE.DivCHED.org
