| This study explored general chemistry students' thinking processes about molecular polarity and related concepts. The study employed a mixed-method design to reveal how general chemistry students use their conceptual frameworks and mental models to solve problems about molecular polarity. In the quantitative phase, I collected student background information (gender, the number of previous chemistry courses) and scores of course exams. Also, three diagnostic instruments were used to gather information in terms of students' understanding and misconceptions about concepts of molecular geometry, polarity, and prerequisite concepts. The design and implementation of the qualitative phase was guided by a theoretical framework of personal constructivism and a case study methodology. The primary data sources were video-taped interviews using a combination of think-aloud protocol and interview-about-events to elicit students' explanations and thinking processes. The secondary data sources were students' artifacts constructed during the interviews and their responses to the items on the three diagnostic instruments. Grounded theory approach, employing a constant comparative method, was used for data analysis.;The quantitative phase involved 159 students. The results of one-way ANOVAS indicated that there were no statistically significant differences for mean scores between male and female students on scores for Chemical Bonding (CB) Instrument (Jang, 2003; Peterson, Treagust, & Garnett, 1989), Geometry and Polarity (GP) Instrument (Furio, Calatayud, Barcenas, & Padilla, 2000; Peterson et al., 1989), exams, or course grade. Only on Electronegativity (EN) Instrument (Taber, 2002b) were scores of male students significantly higher than scores of female students. Also, the results of one-way ANOVA showed that the effect of the number of previous chemistry courses was not statistically significant for students' scores on instruments EN, CB, and GP, four course exams, or course grade. Misconceptions associated with concepts of electronegativity, chemical bonding, bond polarity, molecular shape, polarity of molecules, intermolecular force, and ionic lattices are reported.;For findings from the qualitative phase, I characterized high-, moderate-, and low-scoring students' mental-modeling ability, conceptual frameworks, and features of mental models while solving problems about molecular geometry and polarity. The major finding is that there is a positive interdependent relationship between an individual's level of content knowledge and mental-modeling ability, where one may facilitate or hinder the other.;Findings on comparisons of each student's conceptual framework indicated three prerequisite concepts that may explain students' failure to learn about molecular geometry and polarity. The analyses of students' conceptual frameworks confirmed that when studying student learning about an advanced concept, the scope of the research needs to go beyond examining student understanding about a single concept. Instead, the study needs to incorporate prerequisite concepts to explore students' conceptual frameworks. I also found that metacognitive ability played a significant role in successful mental-modeling process. However, metacognition has not been discussed in research on students' mental models or model-based reasoning.;This study provided empirical evidence for how students' content knowledge, mental-modeling ability, and construction and use of mental models influence their understanding about molecular polarity. The findings have implications for college chemistry education of molecular polarity. |
