Exploring Tertiary Students' Understanding of Covalent Bonding

There has been little research into learners' mental models of chemical bonding at any level, let alone the tertiary level. Undergraduate and graduate students encounter a plethora of sophisticated and highly abstract mental models for chemical bonding, and this study sought to investigate if there are preferred mental models for the concept of covalent bonding for secondary, undergraduate, and graduate chemistry learners. In particular, it was of interest to see whether exposure to increasingly sophisticated mental models at different points in a chemistry education showed up in patterns of preference and use of models in interpreting common physical properties and phenomena. The study revealed that, despite evidencing expertise in a number of highly complex and mathematically sophisticated mental models, tertiary students, including graduates (MSc and PhD), show a strong preference for simple realistic mental models. Furthermore, the students struggled to use their mental models to explain the physical properties of covalently bonded substances.