AN INTRODUCTION TO THE MEANING OF SPARTAN IMAGES


A. View the electron density slice images of lithium*** in the *** folder***.

1. What is meant by electron density?

2. Why do chemists talk of electron density instead of electron position?

3. Describe the electron distribution in a lithium atom. Remember that lithium is three dimensional. Explain how you came to your conclusions from the images.

B. View an electron density isosurface image of lithium. The inner solid surface is a "density (bond)" surface and the outer mesh is the "density" surface.

4. What is meant by an isosurface?

5. What is "iso-" about these surfaces?

6. What is the difference between the solid and mesh surfaces? What does there relative position tell you about the electron distribution in a lithium atom?

7. How do these surfaces confirm your conclusions about the three dimensional electron distribution in a lithium atom?


C. View electrostatic potential isosurfaces of a methanol molecule.

8. What is electrostatic potential? How is it calculated?

9. Is electrostatic potential a vector or scalar quantity? Why?

10. What does the value assigned to an isosurface tell you?

11. What do the relative positions of the electrostatic potential isosurfaces tell you about the distribution of electric charge on this molecule?

12. Are the higher values of the electrostatic potential found inside the lower value isosurfaces?

D. View the image of methanol that shows the electrostatic potential mapped onto its density isosurface.

13. What does the size and position of this surface tell you?

14. What do the colors tell you?

15. Is charge evenly distributed in a methanol molecule? How do you know?

16. Describe the charge distribution in a methanol molecule. Include how this distribution is related to the atoms making up the molecule. Explain how you come to your conclusions.

17. By copying and pasting these images into a drawing program, show how you think 2 methanol molecules might approach each other. Explain your answer.


ME, 1998