Some activites are obviously more thought through than others.
Some activites are obviously more thought through than others.
1.1 Diamond, Graphite, and Buckyballs seem really different. What do you know about the three different materials?
The lecturer can tabulate a list of properties of diamonds, graphite, and buckyballs that are suggeted from students' experiences. For example:
| Diamond | Graphite/Carbon Fibers | Buckyballs |
|---|---|---|
| very hard--hardest known substance | lightweight(CF) | solid is black |
| made from coal (some) | incredibly strong (CF) | made out of carbon, like D and G/CF |
| cuts many other materials | black | |
| solid stone, often cuts into planar facets | flaky | |
| reflects and refracts light | pencil leads | |
| most are colorless | bicycle frames, tennis racquets | |
| very stable | ||
| very expensive/valuable |
At some point in the listing, a student will probably volunteer that one or all of these materials are made of carbon. If this doesn't come out by the time the table of information is compiled, then the instructor should ask questions such as "What is the connection between all of these compounds? How do these three types of material which seem really different end up classified together?"
Once the class has established the differences between diamond, buckyballs, and graphite and have hit on the crucial similarity that all three are made of carbon, then the lecturer goes on to explain element, atoms, isotopes, and other introductory topics.
1.4PS, LA, etc: Draw other atoms--how many electrons, neutrons, etc? What mass, etc (practice reading periodic table / practice with protons and neutrons and electrons.
1.5 Show models of diamond, buckyball, and graphite to the class. Give the students about three minutes to confer with the people sitting near them about which model represents each of the three compounds. Which is diamond, which is graphite, and which is buckyball? After three minutes, ask for a few people to tell what they decided and why. From the answers to the why part, work the student discussion around to structure-property relationships. For example, a student may state that she identified graphite because of the long sheets of material with gaps between sheets. Ask which connections (bonds) between atoms are strongest, the ones in the planes or between planes. Point out that the sheets of carbon atoms sliding over one another act as a lubricant. The same type of discussion with diamond, where the atoms are close together, will reveal that diamond is not easy to break and can only break along the planes of atoms.
PS or lecture activity or something: convert symbol to other symbol: draw C's at vertices, etc.
LA How does structure relate to solubility? Other properties?
Acetylene bond length (1.2 Å) compared to buckyball (1.4 Å)?
2.2 LA- Why do you think that helium is used as the carrier gas in the Smalley apparatus?
2.9Lecture Activity: Show structure of C70. Will C70 exhibit just one
13C NMR signal?
3.1 What are things that you're familiar with that are made of/contain carbon fibers or graphite?
3.2 Why do you think petroleum byproducts are used to synthesize graphite instead of poly(acrylonitrile)?
3.3 pick out unit cells given example lattices. Build lattices given unit cells.
3.4 LA--list more examples of molecular or covalent network solids. Predict which type of solid given examples are. Compare/link to lab.
3.5LA--Why can't amorphous substances be analyzed using x-ray diffraction? Material Science companion demo on X-Ray.
3.6LA--glide planes--bring in diamond cleavage, too. Size calculations/scale up size comparisons.
4.1 Considering the properties of diamonds that have been mentioned, what applications of diamond film technology would can you think of ? Pose this question before mentioning current applications of diamond films; the lecturer should keep a running list of suggestions for comparison with actual applications.
4.2Why do you think that diamond films so hard to make? If diamond, buckyballs, and graphite are the same element, one arrangement of atoms should be more stable than others. Which do you think is more stable and why?
4.3What modern methods of instrumentation might you use to determine if a newly discovered substance were an allotrope of carbon?
4.4Show models of the graphite and diamond structures. Ask why the application of high pressure to graphite should make it adopt the diamond structure? Relate structure to properties. This ties in with the laboratory.
4.8Get them to relate diamond cleavage to glide planes, etc--how does diamond relate to what they did in lab?
4.9 Label Figure 4.6 or even talk about endothermic and exothermic reaction diagrams, etc.
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