Reflection # 3

What:

I have included different pieces of evidence from Organic and General Chem 501 and Inorganic Chem 506 to serve as evidence for my growth through the MCE Program. The first piece of evidence is from Chem 501, which illustrates my struggle to comprehend the concept of the molecular orbital. On the other hand, the later evidence#1 shows my growth of comprehension for the molecular model. Later evidence#2 is a question from Nucleic Acids POGIL in Chem 504 that represents the hydrogen bonds between AT and CG base pairs in DNA double helix. Later evidence#3 is a question from workshop problem in Chem 503. Later evidence#4 In this activity, my students and I used six big balloons to build 3D shapes of a VSEPR model. Students were asked to pop one balloon at a time and study the new shape after losing each balloon. This activity is a replication of what I did in Inorganic Chem 506. Later evidence #5 is a collaborative work in EDU1 class about Demonstration and Modeling in the Science Classroom.

How:

The early evidence and the later evidence show my growth in understanding and synthesis of scientific concepts across chemistry courses. The idea of using 3D to visualize molecules in inorganic chemistry class and using the molecules kit to build real molecules in organic chemistry class was introduced earlier in the first chemistry course, Chem 501, and it was discussed later more in depth in Chem 506. Using VSEPR models is a profound way to predict shapes around an atom, which can be used to explain many chemical phenomena, such as polarity and stability of many molecules. Chem 503 and Chem 504 heavily emphasized on the hydrogen bond and it's importance in living organisms. Furthermore, the geometry of molecules in living organisms dictates its chemical behavior.

Why:

Understanding chemistry concepts involves being able to understand phenomena on three levels of representations: macroscopic, microscopic, and symbolic (Gabel,1999)

I used different pieces of evidence from two different courses to show my initial struggle when the MO and VSEPR models were introduced for the first time. The first course was offered in summer 2006 and the second one in summer 2007. Later, when the same concept was offered for the second time, it was then that I started to see the whole picture. Moreover, the same concept of MO was revisited in Bio-Chem and Spec Chem with focus on conjugated system, delta E, HOMO/ LUMO molecular orbital, and bond gap.

It's a unique character of big ideas in chemistry where the same concept can serve as a useful tool in different chemistry fields. In Inorganic Chemistry, the hydrogen bond seems to be the weakest and the least between the Ionic and the Covalent bonds. However, in Organic-chemistry and in Bio-Chemistry the hydrogen bond seems to be the most important in living organisms.

Conclusion

The use of models in learning and teaching chemistry is a profound tool to visualize the sub-microscopic representation of chemistry. Moreover, using models and 3D representations helped me to understand the idea of bonding and antibonding which stunned me when it was introduced for the first time. However, experimental evidence such as bonds energy and paramagnetic properties in certain molecules proved to be the defect or the limits of the Lewis model to explain these chemical phenomena. Approaching the same topic one more time in Chem 506 helped me to see a complete picture. I spent more time in Chem 506 working on the Lewis model, symmetry, 3D shapes, and drawing x, y, and z axes which helped me to develop a better understanding of MO. I believe both classes Chem 501 and Chem 506 contributed in different ways and various approaches and representations to develop my understanding of MO through using models.

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