Since the summer of 1999, groups of modeling teachers have worked at Arizona State University to try to organize the topics students ordinarily study in high school chemistry around a series of particle models of increasing complexity. In 2005 we began an effort to develop a Modeling Workshop for chemistry with a design parallel to that used in the Modeling Workshop in mechanics. In June 2005 we conducted a pilot workshop in chemistry at ASU. By summer’s end in 2013, 975 teachers have taken Modeling Chemistry workshops nationwide.
The curriculum design was influenced by the CHEM-Study approach which first appeared in the early 60’s. Our work makes the particle models used to describe matter and the treatment of the role of energy in change more explicit. The three questions that guide our approach to understanding chemistry are:
- How do we view matter? (Answer in terms of the particle model you are using to describe matter)
- How does it behave? (Provide an explanation of the behavior using this particle model)
- What is the role of energy in the changes we observe?
In traditional chemistry curricula, students are introduced right away to the modern model of the atom and asked to accept all its complexities as a matter of faith. By contrast, our approach is to start with a simple model of the atom and show students that our model evolves as the need for a better one arises. In each of the instructional units we move from examining phenomena to the patterns we impose on the phenomena to the models we build to help us explain phenomena. Our treatment of the role of energy in both physical and chemical change is sufficiently different from the piecemeal approach found in most curricula that you will want to review it pretty thoroughly before you attempt to teach it. We have also included two evaluation instruments. The Matter Concept Inventory is an assessment of student understanding of the particle nature of matter. It was originally intended for use with an 8th-9th grade physical science course. The Assessment of Basic Chemistry Concepts (ABCC) is adapted from the Chemical Concepts Inventory developed by Doug Mulford (JChemEd-2002). We have modified it to make it more appropriate for use with high school students. What follows is the story line we have used to uncover chemistry. The curriculum materials have undergone testing at our high schools for ten years and have been used in workshops since 2005. Major contributors include Joy Shrode, Brenda Royce, Larry Dukerich, Ray Howanski, Tammy Gwara and Dr. Guy Ashkenazi. If you have any questions, comments or concerns, you should direct them to Larry Dukerich or Brenda Royce.
Article describing Modeling Instruction in chemistry
Outline of curricular materials
- Simple Particle Every substance (element or compound) can be represented as a simple particle (BB) with no internal structure (Democritus model). Addresses concepts of conservation of mass, density of solids, liquids and gases.
- Particles in Motion: Particles are in constant, random, thermal motion. Addresses concepts of temperature as measure of thermal energy, gas pressure, Kinetic Molecular Theory.
- Particles store and transfer energy: The particles exert attractions on one another. Metaphor of energy as conserved substance-like quantity. Addresses concepts of unitary energy concept, energy storage and transfer rather than “forms” of energy and conservation of energy.
- Compound particles: The particles that make up substances can be compounded from smaller particles. (Dalton model) Addresses concepts of laws of definite and multiple proportions, Avogadro’s Hypothesis.
- Atoms/molecules have definite masses: Counting/weighing particles too small to see. Addresses concepts of Avogadro’s Hypothesis and molar mass.
- Atoms with Internal Structure: Development of Thomson model of atom to account for electrical interactions, molecular vs ionic compounds, nomenclature.
Because many chemistry teachers report that they need to address the internal workings of the atom in the first semester (due to district tests), we suggest that they could do units 10 & 11 (in Chemistry-Beyond Core) right after Unit 6. They could then return to Units 7 – 9.
- Atoms in compounds can rearrange: Chemical reactions involve rearrangement of atoms in molecules to form new molecules. Addresses concepts of balanced equations, chemical and thermal energy.
- Introduction to Stoichiometry: Equations representing chemical reactions relate numbers of particles (molecules or formula units) to weighable amounts of these particles.
- Further Applications of Stoichiometry: Equations representing chemical reactions can also relate numbers of particles (molecules or formula units) to volumes of gases, solutions and to the change in chemical potential energy.
Download Progression of Models in Chemistry