Subject Area(s): Molecular Geometry and the Brain, Chemistry,
Biochemistry, Neurochemistry
Associated Unit: None
Associated Lesson: None
Activity Title: Build a Brain Molecule
Molecular model of the brain chemical Glutamate. Photo by Nanthia
Suthana.
Grade Level: 10-12
Activity Dependency: None
Time Required: 55 minutes
Group Size: 3
Expendable Cost per Group: US$ 28.95, from Home Science Tools
http://www.hometrainingtools.com/product_categories/196-specialcategories-bestsellers/products/2884-molecular-model-set-large
Summary
To teach students the importance of the structure of molecules and
how it helps in determining it’s chemical properties.
Engineering Connection
Related to the field of Biomedical Engineering
Engineering Category
(1) relates science concept to engineering
Keywords
Molecular structure, VSEPR theory, Lewis structures
Educational Standards
CA Science Content Standards: 9-12 Chemistry
1) The periodic table displays the elements in increasing atomic
number and shows how periodicity of the physical and chemical
properties of the elements relates to atomic structure. As a basis
for understanding this concept:
a) Students know how to relate the position of an element in the
periodic table to its atomic number and atomic mass.
b) Students know how to use the periodic table to determine the
number of electrons available for bonding.
2) Biological, chemical, and physical properties of matter result from
the ability of atoms to form bonds from electrostatic forces between
electrons and protons and between atoms and molecules. As a
basis for understanding this concept:
a) Students know atoms combine to form molecules by sharing
electrons to form covalent or metallic bonds or by exchanging
electrons to form ionic bonds.
b) Students know chemical bonds between atoms in molecules
such as H2 , CH4 , NH3 , H2 CCH2 , N2 , Cl2 , and many
large biological molecules are covalent.
c) Students know how to draw Lewis dot structures.
d) * Students know how to predict the shape of simple
molecules and their polarity from Lewis dot structures.
e) * Students know how electronegativity and ionization energy
relate to bond formation.
Pre-Requisite Knowledge
Students should already have covered general concepts in atoms,
molecules, chemical reactions, atomic structure and periodicity, and
bonding.
Learning Objectives
Students should be able to draw Lewis dot structures and should know
how to use the periodic table to determine the number of the electrons
for each element. Also students should know how to predict the shape
of molecules.
Materials List
Handout, pencils, molecular model kit, computer, projector, video
clips, paper.
Introduction / Motivation
The brain is made up of billions of cells called neurons. These neurons
communicate with each other with molecules called neurotransmitters
(see/show video of neurons). These neurotransmitters (chemicals in
the brain) allow for everyday functions (movement, vision, learning,
memory, decision making, etc). In a part of the brain called the
hippocampus, learning of new information (facts and events) occurs. If
the hippocampus is damaged in a human, they can no longer learn any
new information (they are stuck in the time when the damage
occurred!). Glutamate is the neurotransmitter in the hippocampus that
makes this happen! Glutamate functions by binding to other molecules
(receptors) on neuron surfaces
.
Procedure
1) Balloon Demo:
Explain the VSEPR theory and explain its relationship to the shape of
molecules using balloons to visualize the following shapes: linear,
trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral.
Inflate a number of balloons together as tightly as you can using piece
of string. Each balloon represents a pair of electrons.
2) Show that the shape of a given molecule will depend on the number
of bonding and nonbonding electron pairs around the central atom.
3) Show video clips on 3D molecular structure.
Make predictions about how the shapes of these molecules will affect
their function. Like CH3 vs. Ch4 how would that change it’s function
4) Discuss Bonding and Molecular structure and how it relates to the
Brain. Molecules in the brain are called neurotransmitters. Show video
of a neurotransmitter binding to a neuron receptor in the brain.
5) Challenge Activity: Build a Neurotransmitter (Glutamate)
Students will work in groups to build and identify all the shapes within
the molecular structure of the Glutamate molecule. Within each group,
pairs of students can work on different parts of the molecule.
6) Chemistry in the Brain: How does the Brain Learn?
Give brief 15 minutes lecture on the brain and how cells use chemicals
to communicate with each other. Specifically discuss neurotransmitters
dopamine and glutamate. Dopamine is involved in reward and
pleasure. Glutamate is involved in learning and memory. Discuss how
caffeine affects the neurotransmitter dopamine and alcohol affects
glutamate.
Attachments
N/A
Safety Issues
Not provided.
Troubleshooting Tips
Not provided.
Investigating Questions
N/A
Assessment
Pre-Activity Assessment
1) Hand out materials: In groups of 3-4, students fill in sheet by
building the different shapes of these molecules using
marshmallows and toothpicks.
Student Handouts:
Molecule
Draw
Lewis
Structure
# of
bondin
g pairs
# of
nonbondi
ng pairs
electron
pair
shape
geometry
polarit
y
# of
bondin
g pairs
# of
nonbondi
ng pairs
electron
pair
shape
geometry
polarit
y
BeH2
BH3
SO2
CH4
BH3
Answer Key:
Molecule
Draw
Lewis
Structure
BeH2
2
0
BH3
3
0
SO2
2
1
CH4
4
0
BH3
(check)
3
1
linear
linear
trigonal
planar
trigonal
planar
tetrahedr
al
trigonal
planar
nonpol
ar
nonpol
ar
bent
Polar
tetrahedr
al
tetrahedr nonpol
al
ar
trigonal
pyramida Polar
l
Activity Extensions
Not provided.
Activity Scaling
Not provided.
Additional Multimedia Support
Not provided.
References
Zumdahl & Zumdahl Chemistry, 7th edition; Houghton Mifflin Company
(2007)
http://scienceteacherprogram.org/chemistry/Gamper99.html
http://www.youtube.com/watch?v=cWx6RbBVTnA
Tang, Y., Shimizu, E., Rampon, C., Zhuo, M., Liu, G. & Tsien, J.Z.
(1999) Genetic enhancement of learning and memory in mice. Nature,
401, 63–69.
Parker, J. (1997) “VSEPR Theory Demo,”Journal of Chemical
Education,Vol. 74, No. 7, p: 776
http://www.meta-synthesis.com/webbook/45_vsepr/balloon1.jpg
Owner
Nanthia Suthana, UCLA Science and Engineering of the Environment of
Los Angeles, NSF GK12
Contributors
This activity has been classroom tested in the AP Chemistry
classrooms at University High School within the Los Angeles Unified
School District California.
Copyright