virtual and tactile molecular models: their complimentary nature in discovery-based general...
TRANSCRIPT
Virtual and tactile molecular models:Their complimentary nature in
Discovery-based general chemistry
Scott A. Sinex and Barbara A. GagePrince George’s Community College
Presented at the 228th American Chemical Society National Meeting in Philadelphia, PA
on 22-26 August 2004.
Are students still in flatland?
CH2CH2CH3
CH2CH3
Where are our students in this world?H
H
H C
H
H
H
C
H
H
C
H
H
C
H
H
C
the computer tools we use…
• ChemSketch – 2D chemical structure drawing (freeware)
• Chime/RasMol – molecular rendering (freeware) great for developing web-based activities
• Spartan – computational (expensive software)
All available in open computer labs !
discovering molecular polarity…
H20 H2S OF2 SF2
CH20 SO3
Use of electrostatic
potential maps in Chime
discovering molecular distortions…Measure the bond angle (H-N-H) and explain any difference
Measure and explain the non-ideal bond angles in each
discovering molecular flexibility…
Are bond lengths and bond angle constant in a molecule?
Can the nitro
groups on ONC rotate around the C-N bond?
discovering intramolecular interactions…With model in hand, ask students how the two chlorine atoms would like to be oriented?
uncovering molecular complexity…
hemoglobin molecule
Type of protein structure?
How many helical chains?
Hydrogen bonding
the tactile model...
shows connectivity displays the real 3D in ideal state possibility of illustrating some
intramolecular interactions (internal rotation)
can test superposition of isomers can generate possible conformer
structures by internal rotation
the tactile model…
is rigid (set bond lengths and angles)
true molecule size and shape not possible
can fall apart! (at least some)
the virtual model…shows true arrangement plus distortions can change orientation and mode of
display including complicated molecules allows measurements provides flexibility – animated vibrations can generate animated reaction
mechanismscan display electrostatic potential maps
A GREAT DISCOVERY TOOL!!!
the virtual model…
may encounter incorrect structure files
may not grasp the 3D nature on flat computer screen
tactilemodels
virtualmodels
Enhanced understanding of molecular structure in general chemistry and
fosters a smooth transition into organic chemistry
in the end…
For further information see our course webpages plus-
Scott Sinex – http://academic.pgcc.edu/~ssinex
Barbara Gage – http://academic.pgcc.edu/~bgage
CONFCHEM Fall 2004 – Teaching Computing in Chemistry Courses Paper #5: Empowering Student Learning with Molecular Visualization Tools in Discovery-based General Chemistry
Thanks to MDL for Chime and ACD for ChemSketch!!!