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 Mark Hayden
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The University of Pennsylvania- Master of Chemistry Education Program (MCEP)
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 Use of Accurate Scientific Language
The participant has grown in his/her ability to accurately use scientific language.

GROWTH
This entry will demonstrate how I have grown in my ability to accurately use scientific language by:
  • detailing my experiences before, during, and after MCE program courses.
  • presenting evidence of instances during specific MCE courses when I used accurate scientific language that I was unfamliar with before the MCE program.
  • reflecting on and explaining how my ability to use accurate scientific language has increased my ability to explain fundamental scientific concepts.

BASELINE EVIDENCE
Predicting and communicating molecular shape (CHEM501 and CHEM506)
Before entering General and Organic Chemistry I (CHEM501) with Dr. Bryan Roberts, I had a very limited understanding of the scientific language that is used to describe molecular shape, particularly for conformers.  To be honest, before my first summer in the MCE program, I didn't even know what a confomer was.  In this particular area, the baseline was zero on enterance to the program.   My experience with Valence Shell Electron-Pair Repulsion (VSEPR) model language and terminology was limited to my experiences within my own classroom since I hadn't used the concepts since my freshman year of undergraduate studies.  At that time, I was only teaching Academic sections, where only a surface treatment of the model was necessary.  As shown in the PowerPoint below, I only touched on the molecular geometries through steric number 4.  Of course, I did not understand or use the terms "molecular geometry" or "steric number" at that time.  Although I was able to identify the shapes by their name (i.e. trigonal planar, tetrahedral, pyramidal, bent), I was not able to engage in a meaningful conversation at that time about molecular shape with a fellow scientist.


 VSEPR PowerPoint (Pre-MCE)



Describing atomospheric regions and chemistry (CHEM505)
Prior to the second summer, when I took Environmental Chemistry (CHEM505), I had very limited experience with the scientific language needed to study or teach atmospheric chemistry.  Although it is extremely difficult to establish a baseline for a lack of skills in language, I have attempted to do this by including a specific question from my pre-test in CHEM505.  Readers will note that I missed the question, which relates to the chemical activity of CFC's in the stratosphere.  The reason that I missed the question is because I had no idea what the stratosphere was and how it related to the specific molecules in question.  Additionally, I was not able to describe any other region of the atomosphere or how it is that the regions are distinguished.

Incorrect CHEM505 pre-test question

EVIDENCE OF GROWTH
Predicting and communicating molecular shape (CHEM501 and CHEM506)
Through my experience with using model kits in the POGIL environment, I learned to discuss and describe simple substituted cyclohexanes.  Below is an excerpt from my conformational analysis project that I completed in CHEM501.  It is designed to show how I have improved in my ability to use scientific language accurately.  In addition to the excerpt, readers will also find a link to the entire webpage, which contains additional use of related scientific language.

Conclusion- Conformational analysis project website (CHEM501)
Chair conformers are often found to be most stable when analyzing simple substituted cyclohexanes.  Substituents in equatorial positions tend to lower the energy, as these arrangements maximize distance and minimize repulsive steric interactions.  The molecule cis-1,4-ditertbutylcyclohexane differs from a simple substituted cyclohexane in that the tert-butyl group is very large.  In this case, the chair conformer is not the preferred shape.  Because both tert-butyl groups are on the same side of the ring, one must be equatorial and one must be axial.  The axial tert-butyl group raises the energy, as it increases steric interactions.

The lowest energy conformer was found to be a type of twist-boat shape.  Although this arrangement increased the steric interactions in the center of the molecule, the tert-butyl groups were both positioned in favorable positions that resemble equatorial arrangements.  This led to the global minimum of 23.9623 kcal/mol.		 Conformational analysis project website

In addition to my experience with conformers in CHEM501, I also greatly improved my ability to use accurate scientific language related to predicting and communicating molecular shape in CHEM506.  In this course, I made most of my gains in language related to the VSEPR model.  Below is a question from my VSEPR quiz.  Readers will encounter a thorough description under the question that is designed to show growth in my ability use accurate scientific language related to the concepts.

The first step in predicting the shape of the molecule is counting the valence electrons so that a Lewis structure can be drawn.  Xenon is known for its ability to accomodate an expanded octet, so at least six Lewis structures combine to describe the actual molecule.  Two of the structures are not drawn because they differ only in the position of a double bond.  These equivalent structures are indicated by the "+ 1 eqv" that is written beside the final two models.  In reality, the actual molecule is a blend between all six, which is indicated by the use of the brackets and the arrows between structures.  However, it is not an equal blend.  The final structure to the right (and its equivalent) is a VERY minor contributor due to the large charge separation and the positive formal charge present on the fluorine atom.  On the other hand, the second structure from the left is the best because it contains no formal charge, while providing all elements in the second series with an octet.

The second step is to predict the shape using VSEPR.  The steric number is 5, because that is how many electron domains exist around the central atom.  When space between electron domains is maximized in this scenario, a trigonal bipyramidal electron-domain geometry results.  In the case of the molecule above, it is important to place lone pairs in equitorial positions, as this arrangement places them as far away from the other domains as possible.  The molecular geometry, "Tee shaped," is attained by ignoring lone pairs.  It is important to note that the angles are less than the normal 180 and 90 degrees respectively.  Without another atom (and its positive nucleus) to reign in the electron density, lone pairs take up more space than bonding domains.


Describing atomospheric regions and chemistry (CHEM505)
One of the first units in CHEM505 dealt with the atmosphere and the chemistry that occurs there.  In order to discuss the atmosphere with other scientists, one must have a thorough knowledge of the related vocabulary and language.  Chiefly, it's important to be able to distinguish between the regions of the lower atmosphere- the troposphere and the stratosphere.  I was surprised to learn that these regions are defined by the altitudes where a temperature minimum and maximum occur respectively.  For instance, as one travels away from the surface of the Earth, a point is reached where the temperature of the atmosphere reaches a minimum.  This is where the troposphere ends and the stratosphere begins.  After this point, the temperature beings to rise in the region known as the stratosphere.  It continues until the temperature reaches a maximum and begins to fall again (where the mesosphere begins).

Below, readers will encounter several pieces of evidence that illustrate my use and understanding of scientific language related to the troposphere and stratosphere, as well as the chemical processes that occur there.  The first is meant to correspond with the baseline evidence.  I was able to correctly answer the very same question in the post-test after I had a grasp on the language.  Next, a portion of problem set #4 is presented that serves as an example of how I have accurately used accurate language to describe the chemical behavior of CFC's in the troposphere and stratosphere.  Finally, I have also included examples of two assessment questions (Exam 1 and Quiz #2 respectively) that illustrate an application of language related to the troposphere and stratosphere respectively.

Correct CHEM505 post-test question
 CFC's and radiation- Problem set #4
 Troposphere application- Exam #1
 Stratosphere application- Quiz #2





REFLECTION
Considering the nature of the MCE grant program, the ultimate measure of any growth is the ability to apply it to one's classroom.  For instance, even though growth in the use of accurate scientific language is a great thing for its own sake, it would be completely useless for me if I was not able to transfer my new knowledge into something that's meaningful for students.  My growth in my ability to use scientific language accurately that resulted from CHEM501, CHEM506, and CHEM505 had the greatest impact on my effectiveness as a teacher.

High school students need to be able to communicate effectively about different parts of molecules.  That was something that I myself was unable to do fully until my participation in CHEM501.  As shown above, my participation in POGIL activities and the conformational analysis website project helped me to identify and discuss regions of molecules such as axial vs. equatorial.  In addition, understanding of vocabulary and language related to conformational isomerism is a tremendous way to teach students about steric interactions and a springboard to discuss concepts such as steric strain.  Often, students attempt to create rings containing less than 5 carbons while working with model kits.  Now I am equipped to verbally explain why they are energetically unfavorable.  Also, I can explain the difference between boat and chair configurations of cyclohexanes.

In addition to communicating about regions of molecules, it's essential for learners to be able to describe their shape.  Once again, my limited language in this area limited my ability to teach the concepts.  As shown in the baseline evidence, my teaching centered around basic molecular geometries of steric number four and below.  After my experience in CHEM506, I became much more comfortable verbally describing molecular models with accurate scientific language.  This, paired with my increased skills in drawing molecules (addressed in Content Entry), provides students with a much better experience in my classroom.

Atmospheric chemistry is one of the most relevant topics for high school students for two main reasons.  First, many students learn about the atmosphere in other science classes and bring interest with them into the course.  Second, nearly all students are aware of the continually attention that the topic receives in the media due to the recent focus on global warming and the push toward green energy solutions.  With that in mind, it's absolutely essential that teachers possess an ability to use language in this area appropriately.  The baseline/growth evidence provided above documents my improved ability to communicate about topics related to the troposphere and stratosphere, the "hot-zones" of atmospheric chemistry.

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