models/modeling

Measuring Surface Tension to Investigate Intermolecular Forces

Like most concepts in chemistry, intermolecular forces takes a bit of imagination and critical thinking to fully comprehend and apply when explaining a variety of situations. Though demonstrating the presence of these forces in a simple and explicit manner can easily be done, I wanted to change how I introduced IMFs a bit this year by focusing on a more data-to-concepts approach.

Two Simple and Cheap Illustrations of Phase Equilibrium and Vapor Pressure

A favorite demonstration is to boil water by lowering the pressure in a bell jar using a vacuum pump. Unfortunately, purchasing a bell jar, vacuum plate, and vacuum pump can run upwards of $1,000 which poses a hardship for many teachers. Here are two simple and inexpensive demonstrations of phase equilibrium and vapor pressure.

Building Models of Isomers

Students will build models of isomers while the instructor walks around from station to station to critique the models. If the model is incorrect, the students rebuild until they get it right. The paper that accompanies this assignment is very easy to grade. 

Balancing Equations with Molecular Models

I am a very firm believer that the world of physical science can be visualized and is an excellent medium for teaching students to model and to picture what happens at the molecular level. The first topic we decided to explore was balancing chemical equations. This seems like such a simple topic to chemistry teachers but I have found that it can be quite challenging for many of my inner city students. The first thing they ask me for is a list of rules that they can follow. We can discuss the problems of algorithmic teaching in a later post! For the time being let’s talk about how to get students to understand why they need to balance equations and discuss what we can call “Conservation of Atoms”.

Geometric Approach to Lewis Structures

If you look at any chemistry textbook, you will see Lewis structures introduced long before electronic and molecular geometries. This makes sense since you need Lewis structures to determine molecular geometry. Unfortunately, research has shown that students often do not recognize that the purpose of drawing Lewis structures is not to create the structure itself but to use it as tool to understand the properties of the molecule (Cooper, Grove, Underwood & Klymkowsky, 2010).

Integrating Three Types of Chemical Representation

This past summer our conversations turned to, “How can we improve our instruction to try and prevent the initial misunderstanding?” We had all read Dorothy Gabel’s article Improving Teaching and Learning Through Chemistry Education Research: A Look to the Future. We were intrigued by the author's description of the three fold system of representing concepts in chemistry.