A Common Core to Chemical Conceptions: Learners’ Conceptions of Chemical Stability, Change and Bonding

Abstract

It is widely acknowledged both that students experience learning difficulties when taught about the submicroscopic structural models that are central to the theoretical basis of modern chemistry, and that students commonly develop alternative conceptions in this topic. This chapter reviews the claim that learners commonly acquire an alternative conceptual framework for thinking about the molecular world from secondary school chemistry teaching. This conceptual framework is based around the notion that chemical processes are driven by the needs of atoms to fill their electron shells. This ‘full-shells explanatory principle’ appears to be the core element around which students develop an understanding of chemical bonding, stability and ionisation, and what occurs during chemical reactions. That is, a range of common alternative conceptions can be seen to form part of a coherent way of making sense of teaching about chemistry at the submicroscopic scale. This octet alternative conceptual framework acts as an impediment to progression in learning chemistry. The chapter outlines the conceptual framework as it was originally characterised in the English curriculum context and reviews evidence from studies in other parts of the world that suggest that this alternative conceptual framework is a significant learning impediment in diverse educational contexts. The chapter considers the nature, and likely origins, of this common core to student conceptions and suggests that implicit knowledge elements, which inform student thinking at preconscious levels, are significant in the genesis of this way of thinking. Further research is needed to better understand the development of student thinking about the molecular world, but our current understanding of the origins of ‘octet thinking’ among students indicates that common teaching approaches need to be modified.