Building chemistry one atom at a time: An investigation of the effects of two curricula in students' understanding of covalent bonding and atomic size.

摘要

Chemists have to rely on models to aid in the explanation of phenomena they experience. Instruction of atomic theory has been used as the introduction and primary model for many concepts in chemistry. Therefore, it is important for students to have a robust understanding of the different atomic models, their relationships and their limitations. Previous research has shown that students have alternative conceptions concerning their interpretation of atomic models, but there is less exploration into how students apply their understanding of atomic structure to other chemical concepts. Therefore, this research concentrated on the development of three Model Eliciting Activities to investigate the most fundamental topic of the atom and how students applied their atomic model to covalent bonding and atomic size. Along with the investigation into students' use of their atomic models, a comparison was included between a traditional chemistry curriculum using an Atoms First approach and Chemistry, Life, the Universe and Everything (CLUE), a NSF-funded general chemistry curriculum. Treatment and Control groups were employed to determine the effectiveness of the curricula in conveying the relationship between atoms, covalent bonds and atomic size. The CLUE students developed a Cloud representation on the Atomic Model Eliciting Activity and maintained this depiction through the Covalent Bonding Model Eliciting Activity. The traditional students more often illustrated the atom using a Bohr representation and continued to apply the same model to their portrayal of covalent bonding. During the analysis of the Atomic Size Model Eliciting Activity, students had difficulty fully supporting their explanation of the atomic size trend. Utilizing the beSocratic platform, an activity was designed to aid students' construction of explanations using Toulmin's Argumentation Pattern. In order to study the effectiveness of the activity, the students were asked questions relating to a four-week long investigation into the identity of an inorganic salt during their laboratory class. Students who completed the activity exhibited an improvement in their explanation of the identity of their salt's cation. After completing the activity, another question was posed about the identity of their anion. Both groups saw a decrease in the percentage of students who included reasoning in their answer; however, the activity group maintained a significantly higher percentage of responses with a reasoning than the control group.