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 28-30 May 2002.

Building A Conceptual Understanding

Microscopic – the particulate nature of matter The atomic level (abstract) 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

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!!

Integrating Technology as a Learning Enhancement Tool

TEACHING Bloom’s Taxonomy TECHNOLOGY Instructional Uses

Evaluation Synthesis Analysis Application Comprehension Knowledge

Modeling & Simulations Animations Data Collection and Graphing Web Searches Drill & Practice Or “Drill and Kill”

Integration Enrichment Automation Modified from Barry Adams, Apple Computer

The following is a text of the emergency chemistry instruction system.

This is only a test!

Can you hit the bull's-eye?

Three shooters with three arrows each to shoot .

How do they compare?

Both accurate and precise Precise but not accurate Neither accurate nor precise

Can you define accuracy and precision based on the graphics above?

How does the mass influence the vibration?

H 2 I 2 MM = 2 g/mole 4111 cm -1 MM = 254 g/mole 365 cm -1 The greater the mass - the lower the wavenumber Estimate the wavenumber for the HI stretch.

2919 cm -1

Have you ever tried explaining the derivative to students?

HCl + NaOH  NaCl + H 2 O The slope between each pair of data points.

pH inflection point changed from increasing to decreasing decreasing slope 7 increasing slope How is the slope changing?

Volume of titrant (mL NaOH)

How about intramolecular interactions?

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

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

The tools of conceptual visualization

• Animation in PowerPoint XP • Spartan ’02 computational chemistry software • • Interactive Excel spreadsheets • • Stella Chime modeling and simulation software molecular rendering freeware Netlogo simulation freeware • Flash animation software (future effort) Click on links above for information/download of software.

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

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

A higher-order thinking example: For the calibration of pH electrode: E = E’ – 0.0591 pH How does the measured voltage, E, vary with pH?

How does the graph change if the glass membrane ages with time?

E ’ What is influenced by a change in temperature?

new E ’ E Slope = -0.0591

E ’ is function of temperature too!

new slope pH

Department of Physical Sciences – downloadable resources at http://academic.pg.cc.md.us/psc Scott Sinex ( [email protected]

) http://academic.pg.cc.md.us/~ssinex see teaching and publications list Barb Gage ( [email protected]

) http://academic.pg.cc.md.us/~bgage see courses taught