Cultivating Conceptual Chemical Thinking: Can You

Visualize It?Scott A. Sinex & Barbara A. GageDepartment 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.

Microscopic – the particulate

nature of matter

Macroscopic - observations or results of an

experiment

Symbolic – mathematical equation or chemical equation

  Building A Conceptual Building A Conceptual UnderstandingUnderstanding

The atomic level(abstract)

How we represent it

The visible world orHow 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!!

I ntegrating Technology as a Learning Enhancement Tool

TECHNOLOGYI nstructional Uses

TEACHI NGBloom’s Taxonomy

Automation

Enrichment

I ntegration

Knowledge

Comprehension

Application

Analysis

Synthesis

Evaluation

LEARNI NGLEARNI NG

Drill & PracticeOr

“Drill and Kill”

Modeling & Simulations

Web Searches

Data Collection and Graphing

Animations

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?

H2 I2

MM = 2 g/mole MM = 254 g/mole

The greater the mass - the lower the wavenumber

4111 cm-1365 cm-1

Estimate the wavenumber for the HI stretch. 2919 cm-1

pHpH

Volume of titrant (mL NaOH)Volume of titrant (mL NaOH)

HCl + NaOH HCl + NaOH NaCl + H NaCl + H22OOThe slope between each pair of data points.The slope between each pair of data points.

How is the slope changing?How is the slope changing?

increasing slopeincreasing slope

decreasing slopedecreasing slope

77

inflection pointinflection point - - changed changed from increasing to decreasingfrom 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 – html activity

(Click on image to load movie- slow, big file)

Can vibrations change the dipole of a molecule?

Movie produced in Spartan ‘02

CH2Cl2

Dip

ole

mom

ent

Cl-C-Cl bond angle

(Click on image to load movie- slow, big file)

Studying Vibrations in Molecules – html activity

The tools of conceptual visualization

• Animation in PowerPoint XP• Spartan ’02 computational chemistry

software• Stella modeling and simulation

software• Interactive Excel spreadsheets• Chime molecular rendering freeware• Netlogo simulation freeware • Flash animation software (future effort)

Click on links above for information/download of software.

Interactive Excel: Interactive Excel: Weak Acid Behavior

Beers Law Simulator

(pdf activity using simulator)

Stella model for Stella model for crystal violet crystal violet

kineticskinetics

Structure and Bonding –Structure and Bonding –a series of Chime a series of Chime

activitiesactivities

Netlogo gas Netlogo gas particle particle motionmotion

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 questionsLet’s look at an example

How does the measured voltage, E, vary with pH?

E = E’ – 0.0591 pH

EE

pHpH

E ’E ’

A higher-order thinking example:For the calibration of pH electrode:For the calibration of pH electrode:

Slope = -0.0591

How does the graph change if the glass membrane ages with time?What is influenced by

a change in temperature?new E ’new E ’

new slope

E ’ is function of temperature too!

Department of Physical Sciences – downloadable resources at http://academic.pg.cc.md.us/psc

Scott Sinex (sinexsa@pg.cc.md.us)

http://academic.pg.cc.md.us/~ssinex

see teaching and publications list

Barb Gage (gageba@pg.cc.md.us)

http://academic.pg.cc.md.us/~bgage

see courses taught