Cultivating Conceptual Chemical Thinking: Can You Visualize It? Scott A. Sinex & Barbara A. Gage Department of Physical Sciences Prince George’s Community College Presented at the Middle Atlantic Regional Meeting of the American Chemical Society held at George Mason University in Fairfax, VA on May 2002.

Microscopic – the particulate nature of matter Macroscopic - observations or results of an experiment Symbolic – mathematical equation or chemical equation Building A Conceptual Understanding The atomic level (abstract) How we represent itThe visible world or How we SEE it

What we want students to do Model data with algebra Use graphical approach with simulations Use science process Understand concepts Visualize at an atomic/molecular level Think critically!!

Modified from Barry Adams, Apple Computer

The following is a text of the emergency chemistry instruction system. This is only a test!

Three shooters with three arrows each to shoot. Can you hit the bull's-eye? Both accurate and precise Precise but not accurate Neither accurate nor precise How do they compare? Can you define accuracy and precision based on the graphics above?

How does the mass influence the vibration? H2H2 I2I2 MM = 2 g/mole MM = 254 g/mole The greater the mass - the lower the wavenumber 4111 cm cm -1 Estimate the wavenumber for the HI stretch.2919 cm -1

pH Volume of titrant (mL NaOH) HCl + NaOH  NaCl + H 2 O The slope between each pair of data points. How is the slope changing? increasing slope decreasing slope 7 inflection point - changed from increasing to decreasing Have you ever tried explaining the derivative to students?

How about intramolecular interactions? Movie produced in Spartan ‘02 di-t-butyl peroxide Discovering Intramolecular Interactions Discovering Intramolecular Interactions – html activity (Click on image to load movie- slow, big file)

Can vibrations change the dipole of a molecule? Movie produced in Spartan ‘02 CH 2 Cl 2 Dipole moment Cl-C-Cl bond angle (Click on image to load movie- slow, big file) Studying Vibrations in Molecules Studying Vibrations in Molecules – html activity

The tools of conceptual visualization Animation in PowerPoint XP Spartan ’02 computational chemistry softwareSpartan Stella modeling and simulation softwareStella Interactive Excel spreadsheets Chime molecular rendering freewareChime Netlogo simulation freewareNetlogo Flash animation software (future effort) Click on links above for information/download of software.

Interactive Excel: Weak Acid Behavior Weak Acid Behavior Weak Acid Behavior Beers Law Simulator Beers Law Simulator (pdf activity using simulator) (pdf activity using simulator) Stella model for crystal violet kinetics Stella model for crystal violet kinetics Structure and Bonding – Structure and Bonding – a series of Chime activities a series of Chime activities Netlogo gas particle motion Netlogo gas particle motion

What are our outcomes? Web-based interactive assignments – both in and out of class More student involvement in class and lab – they are engaged! More integration of mathematics Can ask higher-order questions Let’s look at an example

How does the measured voltage, E, vary with pH? E = E’ – pH E pH E ’ A higher-order thinking example: For the calibration of pH electrode: Slope = How does the graph change if the glass membrane ages with time? What is influenced by a change in temperature? new E ’ new slope E ’ is function of temperature too!

Department of Physical Sciences – downloadable resources at Scott Sinex see teaching and publications list Barb Gage see courses taught