130 Chem. Educ. Res. Pract., 2013, 14, 130--146 This journal is c The Royal Society of Chemistry 2013 Cite this: Chem. Educ. Res. Pract., 2013, 14, 130 Exploring conceptual frameworks of models of atomic structures and periodic variations, chemical bonding, and molecular shape and polarity: a comparison of undergraduate general chemistry students with high and low levels of content knowledge Chia-Yu Wang* a and Lloyd H. Barrow b The purpose of the study was to explore students’ conceptual frameworks of models of atomic structure and periodic variations, chemical bonding, and molecular shape and polarity, and how these conceptual frameworks influence their quality of explanations and ability to shift among chemical representations. This study employed a purposeful sampling technique and used three diagnostic instruments for conceptual understanding to determine the students’ level of content knowledge of the related concepts. Six student interviews were analyzed to portray students’ conceptual frameworks in high and low content knowledge (HCK and LCK, respectively) groups. The study’s major findings revealed that moving from a high toward a low level of content knowledge, the quality of students’ explanations declined, as did their ability to reconcile new information to their existing knowledge frameworks. Three essential concepts – models of atomic structure, effective core charge and principles of electrostatic force, and quantum mechanics descriptions – were identified that may explain students’ failure to learn the necessary aspects of molecular geometry and polarity. This study provides empirical evidence of how students’ content knowledge influences their understanding about molecular polarity. The findings have implications for college chemistry education with respect to teaching concepts about molecular polarity. Introduction Stevens et al. (2010) considered that traditional instruction and assessments often address learning using a piecemeal approach of isolated knowledge and urged future studies to examine how students incorporate and connect ideas in their conceptual frameworks. The present study explored undergraduate general chemistry students’ framework of conceptions and propositions regarding models of atomic structure, periodic trends, chemical bonding, and molecular shape and polarity. These concepts represent a significant portion of the major ideas in the grade 7–12 curricula (Stevens et al., 2010). Also, these concepts involve several unifying concepts (e.g., matter and energy, interactions, models as explanations, evidence, and representations) that the College Board Standards for College Students: Science (a US document published by College Board, 2009) specifies as rigorous knowledge students need to develop for college and their future careers. An understanding of these concepts is also a prerequisite for learning more advanced concepts, including intermolecular forces, properties of solutions, acids and bases, and organic chemistry. Stevens et al. (2010) described learning progression as how students can move towards more sophisticated understanding of the big ideas of science. The move towards expertise requires building a more complex idea upon the understanding of some underpinning knowledge, and incorporating more ideas and connecting to ideas of other related topics. However, previous research has indicated that many students are at a low level in the learning progression and do not possess an adequate understanding required for post- secondary chemistry courses (e.g. Taber, 2003a; Stevens et al., 2010). Although various diagnostic instruments have been developed to investigate students’ alternative conceptions, these alternative ideas or lack of some essential concepts are often addressed as isolated concepts among discrete topics, neglecting the interrelated relationships among the concepts. a Institute of Education, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu, Taiwan. E-mail: cwg25@mail.nctu.edu.tw b Science Education Centre, University of Missouri-Columbia, 321 Townsend Hall, Columbia, MO, USA. E-mail: barrowl@missouri.edu Received 24th August 2012, Accepted 13th December 2012 DOI: 10.1039/c2rp20116j www.rsc.org/cerp Chemistry Education Research and Practice PAPER Published on 03 January 2013. Downloaded on 28/04/2014 01:56:01. View Article Online View Journal | View Issue