Students' conceptions of chemical stability:

One of my publications is

Taber, K. S. (2009) College students' conceptions of chemical stability: The widespread adoption of a heuristic rule out of context and beyond its range of application. International Journal of Science Education, 31(10), 1333-1358. doi: 10.1080/09500690801975594.

Download the author's manuscript version of the paper

Abstract

This paper reports evidence that learners commonly develop a notion of chemical stability that, whilst drawing upon ideas taught in the curriculum, is nevertheless inconsistent with basic scientific principles. A series of related small-scale studies show that many college-level students consider a chemical species with an octet structure, or a full outer shell, will necessarily be more stable than a related species without such an electronic configuration. Whilst this finding is in itself consistent with previous research, the present paper shows how students commonly apply this criterion without consideration of chemical context, or other significant factors such as net charge. Species that would seem highly unstable and non-viable from chemical considerations, such as Na^7-, C⁴⁺ and even Cl^11- , are commonly judged as being stable. This research shows that many college-level students are privileging a simple heuristic (species with full outer shells will be stable) when asked about the stability of chemical species at the submicroscopic level, to the exclusion of more pertinent considerations. Some students will even judge an atom in an excited state as more stable than when in the ground state, when an electron is promoted from an inner shell to 'fill' the outer shell. It is suggested that the apparently widespread adoption of a perspective that is so at odds with the science in the curriculum is highly significant for the teaching of chemistry, and indicates the need for more detailed studies of how such thinking develops and can be challenged.

Introduction: Chemical reactions in school science
- An 'Explanatory Vacuum' at School Level
- The Octet Heuristic and Octet Thinking
Student Ideas about Chemical Stability
- A Surprising Finding
- A Probe to Explore Student Thinking about Chemical Stability
Purposes of the Present Research
- Testing Generalisation across Student Samples
- Checking the Significance of 'Stability' Judgements
- Testing Generalisation across Chemical Examples
Methodology
- Principles of Instrument Design and Analysis
- Sampling of Learners
Study 1: Replication in a new institutional context
Study 2: The significance of relative stability
- Results from the Stability/Reactivity Probe
Study 3: Range of application of students' chemical stability concept
- Responses to the Variegated Chemical Stability Probe
Discussion
- Judging Stability in Context
- Alternative Conceptions
- Implications for Teaching
- The Next Swing of the Methodological Pendulum