Students’ Conceptions about the Sub-Microscopic Approach to Explanations in Chemistry Throughout their BSc Degree Course

Abstract

The main objective of this study was to test chemistry students’ competence, throughout the entire BSc course at North-West University (Mafikeng Campus), in the use of the important and widely applicable strategy of explaining the facts, principles and laws of chemistry in terms of the properties of the  constituent sub-microscopic particles. Seventeen questions were used for systematically testing all  basic aspects of chemistry. The aspects tested included the following: the types of particles present and
their properties in various types of matter (e.g. metals, non-metals, ionic compounds, covalent  compounds, mixtures, gases, liquids, solids, solutions); the changes in the nature, arrangement and properties of the particles during both physical and chemical changes; the explanation of physical and chemical properties of substances in terms of the properties of the constituent particles. Student performance was consistently bad and it did not improve as they progressed from year to year in their BSc course. More than half of them (average performance in all questions) had difficulty in answering the questions. Analysis of students’ answers suggested that most students’ difficulties were due to their not identifying clearly the problem that had to be solved and their not using the relevant principles and reasoning to solve the problems. Instead, most students tried to solve problems by recalling knowledge, procedures and solutions they had learnt. The lack of improvement from year to year indicates the need for continuously training students in the sub-microscopic approach to interpretations and explanations throughout the BSc course, and not just in the first year as is done presently.

KEYWORDS: Sub-microscopic particles, sub-microscopic approach, properties of matter, explanations in chemistry.