Here you can read a description of the Chemical Control thread of the Chemical Thinking framework.
Here you can read a description of the Chemical Identity thread of the Chemical Thinking framework.
Here you can learn about the Chemical Thinking Learning Progression (CTLP) project that spawned the Assessing for Change in Chemical Thinking (ACCT) project.
Read about our rationale for the development of the Chemical Thinking framework here.
Access formative assessments developed by the Sevian research group past ACCT cohort participants according to the chemical thinking questions that they uncover.
Categories of ways that students think about the concept of chemical identity.
“What are the effects of using and producing different matter types?” is a question of consequence evaluation, because chemistry depends on context and affects the human experience. The life cycles of materials, including production, consumption, and disposal, have benefits, costs, and risks in many dimensions. These include social, economic, political, ethical, environmental, and ecological consequences. While the ultimate aim of chemistry is to improve the human condition, the design of chemical processes involves making decisions based on limiting consumption of energy, using renewable resources, and reducing or eliminating production of toxic byproducts. This chemical thinking question is often central to sustainable action work, such as evaluating which refrigerants are better than Freon, or designing a greener battery.
“How can the effects be controlled”? Is a question that involves making choices about which internal and external parameters to modify to maximize benefits and minimize costs and risks. While outcomes can be predicted based on models, in real processes there are often many variables which cannot be easily controlled, and many conditions that constrain the processes. Feedback loops of testing and refining are often used, resulting in design processes that converge on a desired outcome (maximizing, minimizing, or stabilizing output), usually making tradeoffs among different properties (such as price, quality, safety, and environmental impact). This chemical thinking question is often central to design activities, such as producing biomass or reducing the toxicity of combustion exhaust fumes.
“How can chemical changes be controlled?” is a question that involves understanding how changes in conditions affect the relative stability of the species involved in a chemical process. Control can be achieved by selecting reactants with structural features that change their energetic stability, varying the concentrations of reactants or capturing and removing products, adding substances which react with intermediates to facilitate or inhibit different mechanistic steps, changing temperature to activate chemical species,, or choosing solvents that facilitate or inhibit certain interactions. For example, controlling the replication of a virus may involve tuning conformations of a substance involved in the replication to block one pathway in the process. This chemical thinking question is often central to chemical process design and analysis activities, such as improving solar cell operation, analysis of battery efficiency, or characterizing the degradation of a dye.
“What affects chemical change?” is a question of identification of internal and external variables that affect the extent and rate of chemical processes. The extent to which reactants are transformed into products and the rate at which the transformation occurs depend on internal factors such as the composition and structure of the particles involved and their concentration in the system, as well as on external factors such as temperature, pressure, and the nature of the environment in which the reaction takes place (e.g., type of solvent, pH). Identifying these factors and their effects on reaction extent and rate allows us to design and control chemical processes for particular purposes.