Forging Chemical Connections
among the Symbolic, Macroscopic,
and Microscopic Realms: Getting
Students to Visualize and
Understand Using Technology
Scott A. Sinex
Barbara A. Gage
Prince George’s Community College
Presented at the Middle Atlantic Regional Meeting of the American Chemical
Society held at Princeton University, Princeton, NJ, 9-11 June 2003
A World of Symbolism
N2(g) +
N2 & H2
3H2(g) 
2NH3(g)
NH3
What is the difference between the contents of the two
boxes?
What happens if the substances in the first box react?
What if one substance occurs in excess?
As chemists,
we employ models
• Physical models – wooden
ball & stick or the syringe
• Conceptual models –
“molecules in the box”
V
• Mathematical models –
Boyle’s Law or Beer’s Law
P
PV = k
Beer’s Law – How do they grasp?
Calibration Curve
A = mc
Absorbance
1.00
0.80
0.60
0.40
0.20
0.00
0.00
0.10
0.20
0.30
0.40
0.50
0.60
Concentration (M)
Beer’s Law Simulator
N2 (g) + O2 (g)  2NO (g)
What happens
if you get
this?
The Three Realms of Chemistry
Microscopic –
the particulate
nature of matter
The atomic level
is the
mental
(abstract)
What
model
that our students have?
Symbolic –
mathematical
equation or
chemical equation
Macroscopic observations or
results of an
experiment
How we represent it
The visible world or
How we SEE it
Building an
understanding…
• Conceptual
– static  dynamic
• Mathematical (using algebra)
– discover relationships from data
• Connecting the realms
– macroscopic, microscopic, symbolic
…and following national standards!
The chemist’s toolbox…
• Graphing calculator/Excel – data handling,
analysis, and modeling
• Chime – interactive molecular models in webbased activities
• Spartan – model building, animations
• Stella/Interactive Excel – mathematical
simulations
• Netlogo/Java applets – particle/reaction
simulations
• PowerPoint – animated discussion/elaboration
and interactive tutorials
Support documents for
students…
•
•
•
•
•
•
Chime - HTML interactive online
TI-83 Graphing Calculator – pdf file
Excel – pdf file
PowerPoint – pdf file
Stella – for using simulations – pdf file
Spartan – on organic lab manual CD
http://academic/pgcc.edu/psc
A journey into molecular geometry…
Styrofoam balls and toothpicks
Construct and discover
Ball & stick models
Ideal geometries
Chime molecules
Ideal geometries
Lone pair distortion
Molecular polarity
Boiling Point Trends
200
BoilingMolar
Point (oC)
Mass
250
200
150
150
100100
50
Boiling
Points of Homologous
alkane
alcohol Series
thiol
50
0
-50
0
-100
0
-150
0
-200
CH3SH
CH3OH
CH4
2
2
4
6
Number of Carbon in Chain
8
4
6
8
Number
in Chain thiol
alkane of Carbon
alcohol
10
10
Molecular polarity activity
Advantages of Chime
• Freeware – plug-in for Internet
Explorer or Netscape
• Use freestanding in web browser
software or web pages
• Interactive – positioning and
measurements (distances, angles)
• Multiple representations of molecules
• Electrostatic potentials maps - polarity
• Animations – reaction mechanisms or
vibrations
Compare and contrast the internal
rotation of the O-O bond in
di-t-butyl peroxide
The wooden
ball and stick
model
Dance of the Molecule
Computergenerated model
(Spartan 02)
What does technology
provide…
•
•
•
•
•
•
Interactive and dynamic visualization
Mathematical modeling and simulations
Measurements – bond distances and angles
Multiple representations
Animations of vibrations
Illustration of reaction
mechanisms
Avoiding this
mental model
• Examination of more
complicated molecules
The classroom…
• Becomes more learner-centered
• Models discovery learning and science
process
• Involves investigative learning activities
that strengthen problem solving skills
through data-driven modeling and use of
the WWW
• Promotes more discussion and elaboration
and utilizes less lecture
• Provides more connections to biological
molecules
Contact information
College Pathways to the Science
Education Standards (NSTA, 2001)
Scott Sinex
ssinex@pgcc.edu
http://academic.pgcc.edu/~ssinex
Barbara Gage
bgage@pgcc.edu
http://academic.pgcc.edu/~bgage