Visualizing three-dimensional structures is a major hurdle for chemistry students. Compounding the difficulty, chemists use three different concepts to imply geometry, although there is no obvious geometric information in two of them. The bond angle (a geometric construct) can be known from noting either the hybridization of the central atom (a quantum mechanical construct) or the coordination number (the number of other atoms bonded to the central atom).

3-D Angles uses pattern recognition principles introduced through rapid repeated exposure to three concepts to teach students to intuitively associate the three terms together in order to be able to correctly recognize the molecular structure from limited information.

3.0 (October 19, 2010)

Windows XP, Windows Vista, or Windows 7

3-D_Angles_Setup.exe (2.94 MB)

Note: If you run 3-D Angles and the program's display appears blank, you need to obtain updated video card drivers that support the OpenGL graphics library.

Visualizing three-dimensional structures is a major hurdle for chemistry students. Many molecular modeling programs have been designed to assist visualizing organic structures; fewer exist for crystalline compounds.

Crystalline Solids attempts to meet that need. The program provides easily manipulated three-dimensional models of fundamental crystal structures. Students can turn and rotate either single or multiple unit cells of any of the fourteen Bravis lattice structures. They can toggle between structures where the atoms are represented by small spheres, similar to ball-and-stick models, or large spheres, which simulate the space-filling nature of the atoms in a crystal.

Close-packed cubic and hexagonal structures provide the additional features of studying interstitial sites/holes, or close-packed planes and slip planes. Students can place atoms in small or medium sites and turn on or off the axes between the atom in the site and its nearest neighbors, or the edges of the tetrahedron or the octahedron formed by these nearest neighbours. Visualizing packing patterns is simplified by highlighting sequential close-packed planes or slip planes.

At UCLA the program is used routinely in general chemistry, in intermediate inorganic chemistry, in a graduate solid-state class and in a chemical engineering course. We have longitudinal evaluation data on its effectiveness in general chemistry.

3.0 (October 19, 2010)

Windows XP, Windows Vista, or Windows 7

Crystalline_Solids_Setup.exe (2.60 MB)

Note: If you run Crystalline Solids and the program's display appears blank, you need to obtain updated video card drivers that support the OpenGL graphics library.

GraphLab teaches basic principles and skills for graphing. The program is divided into four lessons: scaling, drawing a "best-fit" straight line, errors, and least-squares fit.

*Scaling: *Requires students to set the scales for graphs in which the variables
that involve direct and inverse proportions and in which the scale involves exponents.
Students must provide equally spaced intervals.

*Best Fit Line: *Students move a line with the mouse and place it so that
the best fit of the data is obtained. The slope of the line must agree within 5%
of the calculated least-squares-fit line.

*Errors: *Scientific data can contain either random and/or systematic errors.
In this lesson, students must place the line to give a best fit and then decide
based on the phenomena being described what kind of errors the data contain.

*Least Squares Fit: *In this lesson, students draw the least-squares line
by minimizing the sum of the squares of the differentials, which is shown on the
screen as they place the line on the data. The differentials are also shown to provide
a visual sense of the minimization. Finally, students are confronted with an "outlier"
when they are drawing the least-squares line. In each section students are presented
with clearly stated principles and guidelines for graphing illustrated in an accompanying
graph of real data from various science subject areas. Following each new principle,
students are asked to summarize and evaluate that information. This informative
phase is followed by an exercise phase in which students practice the skills.

5.0 (October 19, 2010)

Windows XP, Windows Vista, or Windows 7

GraphLab_Setup.exe (2.25 MB)

Graphlab Description (.pdf
file, requires Adobe
Acrobat Reader)

Graphlab Exercise (.pdf file, requires
Adobe Acrobat Reader)

This exploration is a small program that must be downloaded onto your computer.

Click here to download this exploration (a Microsoft Excel file)

Siobhán Freitas

WebCT is used to deliver instructions, content, and to collect student responses for this exploration.

Kinetics
Worksheets (.pdf file, requires
Adobe Acrobat Reader)

Kinetics Graphing Worksheets (Microsoft
Excel file)

Send e-mail to cpr@nslc.ucla.edu for more information about accessing this exploration.

Chemists have developed advanced written notations to convey the structure of molecules. Although the symbolism represents only the connectivity of the atoms, these impoverished representations imply the specific geometry of the molecule.

Representations trains students to relate the notation of the impoverished drawing with the richness of the three dimensional structure of the molecule. Random presentation of a variety of impoverished drawings, typical of textbooks, are compared with three-dimensional models of rotating molecules drawn using advanced lighting and rendering techniques. The models may be correct or may include logical but incorrect interpretations of the drawing. Students identify the accuracy of the model and receive corrective feedback if appropriate.

3.0 (October 19, 2010)

Windows XP, Windows Vista, or Windows 7

Representations_Setup.exe (2.46 MB)

Note: If you run Representations and the program's display appears blank, you need to obtain updated video card drivers that support the OpenGL graphics library.This site was established to provide chemistry students with NMR spectral problems.

Interpretation of NMR spectra is a technique that requires practice - this site provides 1H NMR and 13C NMR spectra of different compounds for students to interpret. Hopefully, these problems will provide a useful resource to better understand NMR spectroscopy.

This project is supported by Cambridge Isotope Laboratories, the UCLA Department of Chemistry and Biochemistry, and the UCLA Science Challenge.

Web - Try WebSpectra now

Craig Merlic

Barry Fam