5. What drives chemical change?

“What drives chemical change?” is a question of why chemical processes happen. Chemical reactions occur to different extents and at different rates. To what extent reactants will be converted into products depends on the relative potential energy of their submicroscopic components as well as on the relative  configurations these components can adopt. The speed of a process depends on the mechanism of the reaction and on the concentration of those species that limit the reaction rate. Both reaction extent and rate are affected by the temperature of the system. Understanding the drivers of chemical change is critical for predicting, explaining, and controlling processes of interest, from making soap to reducing pollution. 

4. How does structure influence reactivity?

“How does structure influence reactivity?” is a question of connection between chemical structure and behavior. The specific ways in which the submicroscopic particles of matter interact with each other and are transformed into different chemical species depend on their atomic composition and molecular structure. The types of atoms present in a molecule and their relative arrangement  in space affect the distribution of the electrons that can participate in bonding processes with other particles. Understanding how molecular structure affects electron distribution, and how this in turn determines how different particles interact and react with each other is critical to design the synthesis of desired materials and to control chemical processes. 

1. What types of matter are there?

“What types of matter are there?” is a question of classification. Classification is a very important tool for predicting and explaining the properties of substances in our surroundings. For example, classifying a material as a metal versus a nonmetal allows us to predict that it may conduct heat and electricity quite well. Similarly, identifying a substance as an ionic compound allows us to explain why its aqueous solution conducts electricity. Classifications are often loose categories with gray areas, but they support chemical thinking when seeking to synthesize new substances, determine the identity of a material, or control a chemical process.   

3. What properties of matter types emerge?

“What properties of matter types emerge?” is a question of the origin of properties. Predicting or explaining properties of substances often requires analysis of structural rather than compositional aspects of substances, and involves reasoning about emergence rather than arguing based on a central cause. Explaining behaviors of substances involves examining what influences energetic stability and how behaviors on one distance scale emerge from dynamic interactions between structural components on a smaller scale. There are many different scales at which these structure-property relationships are built (from multiple entities in mixtures down to electronic structure). This chemical thinking question is often central to predicting properties of substances, e.g., which oil is best for lubricating a transmission or frying plantains or making soap.

The Rain Puddle

A formative assessment designed by an ACCT cohort member designed to investigate student understanding of chemical mechanism.

Balancing with Legos

A formative assessment designed by an ACCT cohort member designed to investigate student understanding of chemical mechanism.