Teacher Trainees’ Interpretations of Chemical Stability and Chemical Reactivity Ruby Hanson University of Education, Winneba, Ghana Abstract This paper reveals teacher trainees’ over- reliance on the octet model. It assesses the nature and possible origins of these conceptions. One hundred and thirty-eight teacher trainees in a teaching university, who were purposely selected, participated in this case study. Instruments used in gathering data were worksheets and focus group interviews. Data obtained were analysed quantitatively and qualitatively. Records of the interviews were transcribed after thematic descriptions. Findings showed that majority of the trainees relied heavily on the full shell concept model, which they imbibed from teachers, and so confused the chemical reactivity framework with that of chemical stability. This led them to pay attention to irrelevant features to the negligence of other authentic reasons in their assigned task. The octet model also led the trainees to reduce the relevant number of propositions that they could have considered as possibilities in differentiating between models. These findings will add to existing knowledge among the science learning community as they are relevant to educators interested in conceptual development and students’ learning progressions. Remediation was recommended to enable the trainees to form proper mental models of the concept of chemical stability and its application through innovative constructivist teaching strategies. 1. Introduction Chemistry, as a discipline, is found in almost all other science-related programmes and vocations such as nursing, medicine, pharmacy, agronomy, chemical engineering, research and many more. Yet, students shy away from the study of chemistry because of a few basic, but abstract rule-governed principles [1] that must necessarily be well understood for further higher learning. Research shows that students struggle to comprehend how chemical reactions occur, even in laboratory practice settings where they are exposed to tangible substances [2, 3, 4, 5]. Helping students to relate among the macroscopic, and tangible properties of matter, as well as their chemical compositions, and structures at the sub-microscopic levels in a practical manner, is a vital goal in the teaching of chemistry. Students often experience learning challenges when they have to deal with visualisations of these sub- microscopic structural models such that they develop alternative conceptions about them, and particulate matter in general. They prefer to live in a world where they can see and feel. Thus, when they have to deal with chemical reactivity, where reacting species cannot really be ‘seen’ in their microscopic forms, they think of the phenomenon as a situation where species merely undergo changes in their systems to attain ‘stability’ [6]. Students’ perception of ‘stability’ is one about matter that is at ‘rest’ and ‘chemically inactive’ because it has attained a full ‘outer shell’, ‘orbital’ or ‘configuration’. In other words, a system which is deemed to be ‘stable’ would not be prone to ‘attach’ itself or be ‘involved’ in further chemical reaction. Students perceive the stability of compounds as the need of atoms to fill their ‘electron shells’; that is, the full electron shell configuration or octet model [1]. This suggests that teachers must provide opportunities through practice, for learners to acquire scientific knowledge alongside their own activities through purposeful interactive discussions. They must create situations that can enable learners to apply other acquired knowledge to reinforce new knowledge. This would enable them to hold discussions and reflect on their discursive discourses in a minimal corrective and crosscutting environment [7]. Students in the high school exhibit in their answers to questions on chemical stability that chemical species with octet or full outer shell presentations are more stable than those with other configurations. Species with octet presentations actually tend to dominate in discussions that concern molecules, ionic lattices, and metallic lattices [6]. Students therefore extend this idea to believe that species with structures such as Mg 6- and Na 7- all carry the octet and so are stable, without due consideration to feasibility on the basis of thermodynamic requirements. It must be noted that the octet framework has pedagogic values as it could be used to explain how some common alternative conceptions are epistemologically related. Chemical stability is a concept that describes the tendency of a chemical system to ‘resist’ change due to its thermodynamic stability. In terms of energy factors, what this implies is that a system will preferably be in its lowest energy state with its International Journal for Cross-Disciplinary Subjects in Education (IJCDSE), Volume 9, Issue 4, December 2018 Copyright © 2018, Infonomics Society 3906