Chemistry students' explanations of ionisation energy phenomena often involve a number of non-scientific or inappropriate ideas being used to form causality arguments. Research has attributed this to many science teachers using these ideas themselves (Tan and Taber, in J Chem Educ 86(5): [623][624][625][626][627][628][629] 2009). This research extends this work by considering which atomic models are used in pre-service teachers' explanations and how that relates to the causality ideas expressed. Thirty-one pre-service teachers were interviewed. Each was asked to describe and explain four different atomic representations (Rutherford, Electron cloud micrograph, Bohr and Schrödinger types) in as much detail as they could. They also provided an explanation for the subsequent ionisation energy values for an oxygen atom and identified which representations were helpful in explaining the values. Significantly, when preservice teachers only used Bohr type representations, they did not use repelling electron ideas in their explanations. However, arguments that were based on electron-electron repulsion used features from Schrödinger type atoms. These findings suggest that many pre-service teachers need to develop their atomic modelling skills so that they select and use models more expertly and that subsequent ionisation explanations offer a context in which to explore different atomic models' limitations and their deployment as explanatory resources.

The effect of intervention activities on the chemistry content knowledge of 92 preservice chemistry teachers (PSCT) was examined via a pre and post true/false with confidence level test focusing on ionisation energy values and the use of a common alternative conception (AC). Data were collected from three cohorts of PSCT each engaged in a one year full-time universitybased teacher education programme. Comparison of pre-and post-test responses and discrimination differences between responses for each PSCT were used to identify the use of the AC and hence the efficacy of the intervention activities. Interviews with 14 of these PSCT allowed triangulation of the data. Findings suggest that the activities allow 71% of PSCT to identify this AC as non-scientific or become more confident in doing so. Interview data indicate that this rejection of this AC is sustained for 9 of the 11 PSCT whose test data indicated improvement. These data have implications for teacher education such that 2 hour intervention sessions can offer the opportunity for PSCT to develop their subject matter knowledge. As the accurate application of electrostatic concepts to electrons has wider application to bonding, these interventions offer PSCT more accurate chemical subject knowledge resources to draw on in their teaching. ARTICLE HISTORY

No abstract

Background: Currently there are international concerns over teacher recruitment and attrition rates, especially in mathematics and the physical sciences. Much has been written about the recruitment of student teachers and the reasons people give for going into teaching, but little on the broader context of these people's lives and the complex influences on their career decisions.Purpose: The narrative approach used in this study is a complement to larger scale quantitative studies into teacher recruitment as it seeks to consider the wider picture of a person's life and, through a defended participant perspective, expose influences that may not have been obvious to the participants themselves. Sample: Eight current UK chemistry teachersDesign and methods: Stories of becoming teachers are told through interviews and these narratives examined to consider the key influences upon their becoming chemistry teachers. Two analytic lenses were used: inductive thematic analysis and deductive analysis considering psychoanalytical defences. These lenses were used to both exemplify and challenge each other, providing triangulation of interpretation to determine participants' trajectories into chemistry teaching.Results: Family background and interest in, and utility of, studying chemistry were found to influence career life decisions. Some participants experienced moments where their career trajectory changed towards teaching whereas others followed a smooth path towards this end. For two, changes in their relationship with chemistry resulted in a teaching career. Particularly influential appears to be prior teaching experience which led to changes of trajectory for half of the participants in this study. Conclusion:The chemistry teachers' relationship with the subject discipline and prior teaching experience were important in them entering the profession, whilst the influence of their own teachers is more nuanced than wider larger scale quantitative studies suggest. Findings suggest that increasing the opportunity for classroom experience for undergraduates may improve teacher recruitment.