MISEP Chem 512 – Jacobs
Final EU paper and reflection
Tienne Moriniere-Myers
Post-Course Evidence Essay
I have selected the following enduring understanding to discuss in this
essay.
Learning and communicating about chemistry is highly dependent on
understanding the symbolism and representations of the discipline.
Molecules can be represented in many ways, and each representation has
its own strengths and weaknesses. Therefore, the appropriate
representation to use in a given context depends on what you are trying to
get across about the molecule in question.
Learning and communicating about chemistry is highly dependent
on understanding the symbolism and representations because this is a
pictorial language.
http://www.usm.maine.edu/~newton/Chy251_253/Lectures/
Like other languages it has a number of related terms that are used in
different situations. The key to understanding chemistry is to have the
ability to read the language and recognize patterns and to understand the
codes and the meanings of the names.
A molecular formula describes the number of different kinds of
atoms in a molecule. (CH4) It indicates the actual number of each type of
atom. . In a condensed formula (CH4O) each element appears only once.
Structural formula represents a two-dimensional model of how the atoms
are bonded to each other. (CH3CH2CHO) (Denniston, 2004).
Lewis structures show the bonding between atoms of a molecule. These
structures can be drawn to show how molecules are covalently bonded.
For example, carbon to carbon bonds can be single double or triple. In the
examples below, each carbon atom has four dashes, which represent four
bonding pairs of electrons, satisfying the octet
rule.
These representations help explain the overall structure of the molecules.
Working with these structures gives a familiarity and recognition of
patterns and groups that lead to similar chemical characteristics. The
number of possible molecular combinations is limitless and being able to
read the language of these structures aids in understanding threedimensional models.
Three-dimensional models represent the molecule in a physical
display. Manipulating models can aid in interpreting observations and
testing understandings of chemical reactions. In class we observed a threedimensional model of DNA using the Jmol website. A single strand of DNA
is a polymer composed of nucleotides. Each nucleotide consists of
deoxyribose sugar, phosphate, and one of the four nitrogenous bases:
adenine (A), thymine (T), cytosine (C) and, guanine (G). The model
allowed us to isolate the sugar/phosphate backbone and to rotate the
structure to observe the protruding bases according to the base pair rule.
Adenine protruding from on strand always pairs with Thymine protruding
from the other. Guanine always pairs with Cytosine. We were able to
transfer our knowledge from the 3D computer model to hand held models
moving into groups to form the nitrogenous bases.
I teach students a method to build a DNA model in a Saturday
science program. The students use different color beads to represent
adenine (blue), thymine (red), cytosine (yellow), guanine (green). The
sugar/phosphate backbones are represented by 2 long pipe cleaners. The
hydrogen bonds between the nitrogen bases are short white pipe cleaners.
The interactions that we had and the concepts we learned while we
manipulated the models proved to me that models are not valuable and can
lead to misconceptions without understanding the basic dialect of
chemistry.
Reflection
The piece of evidence I chose for this reflection is Quiz#1: Chemistry
fundamentals. I can remember in preparation for the class looking at the
structures in the textbook and thinking that Chemistry had language of
picture diagrams and I was excited that I was going to learn how to read
them.
Looking back on my pre-homework assignment I had a vague idea of
the rules for the language of Lewis structures. I met with Dr. Jacobs for
tips on how to make the constructions and she assigned multiple problems
for me to practice. I spent time working through the problems and she
gave me immediate feedback, reminding me to, 1) count the total valence
electrons, 2) octet rule, 3) minimize formal charges. I worked with my
cohort members and successfully completed the assigned homework
problems. I really felt I knew how to make Lewis structures. The time
came to perform on a quiz #1. I got very nervous when I first saw the
problems. Looking at the 3 Lewis structure problems, I realized that
although I had practiced and spent hours working though the assignments
I did not know, until that moment, that I really did not know how to
proceed and accomplish the task. I realized that I did not understand all
the rules and I did not fully understanding the dialect of the
representations. This was my first experience thinking I understood
something, not knowing, I truly did not understand. At that point I knew
that I would have to practice this new language and that I had to have
active control over the process of my thinking (metacognition). My goal
was to become proficient in making and understanding these structures.
I chose this because I feel this was valuable information for me to
gain as an educator. Feeling what my students experience when they work
hard to learn a concept but just can’t “get it “, was a priceless experience.
As we progressed through the course I could see the importance of
knowing how to construct and analyze Lewis structures because we were
building on these basic fundamentals. The last unit we studied was DNA,
the chemical bond between nucleotides and replication. I have gone from
constructing basic Lewis structures, to understanding and drawing
diagrams that represent the first step in the reaction that joins the new
monomer to the growing chain of DNA, along with carefully monitoring my
learning.
The concepts I have learned in The Chemistry of Living Organisms
and the understanding I have gained in the process of thinking will be very
valuable in monitoring and evaluating the progress of my students, as well
as my own.
References
Denniston, K., Topping, J., Caret, R. (2004). General, Organic, and
Biochemistry. New York: McGraw Hill.
The University of Southern Maine (n.d.) O=CHem. Retrieved August 17,
2007, from http://www.usm.maine.edu/~newton/Chy251_253/Topics.html