Students' Visualization of Metallic Bonding and the Malleability of Metals

Abstract

This study investigated the mental representations of metallic bonding and the malleability of metals held by three male students aged 14-15 (Year 10) who were attending a Hong Kong school. One student was selected by their chemistry teacher as representing each of the highest, the medium, and the lowest level of attainment in chemistry in a school that admitted students of average general attainment. The students were interviewed and their understandings probed through their provision of drawings and their interpretation of the diagrams that had been previously used by their teacher. Dual coding theory was used to interpret the relative significance of visual and verbal input and the interaction between the two for their understanding. There was evidence that students relied on verbal recall in providing their initial understandings and showed an appreciation of the nature of the structural components of the electron-sea model of metallic bonding. However, they varied in terms of their appreciation of the electrostatic force which was responsible for the malleability of metals. The study suggests that a clearer understanding of the electrostatic force involved can be attained when students experience visual and verbal representations simultaneously, a conclusion supported by dual coding theory. Principles for good practice in using diagrams in teaching are discussed.

The Use of Representations and Argumentative and Explanatory Situations

“…Furthermore, the use of different representational modes, both by the students and the teacher, supported communication in the classroom, allowing for mutual understanding and the negotiation of meanings. This result was seen to be in line with other studies that highlight the fact that different resources for communication are common and necessary in science, especially in the case of chemistry (Adadan, 2013;Cheng & Gilbert, 2014;Gilbert, 2005;Kozma & Russell, 2005).…”

Understanding metallic bonding: Structure, process and interaction by Rasch analysis

“…Previous studies have suggested that students face many challenges in learning this model (de Posada, 1997;Taber, 2003b;Coll & Treagust, 2003). In an interview study, Cheng and Gilbert (2014) postulated that the learning was challenging because it involved a conceptual change from the focus on structure (in the simple particle model) to a focus on the intangible electrostatic force also (in the free electron model). We sought to extend their work by examining a larger population of students to determine whether learning the electrostatic force was more challenging than learning it as a structure.…”

“…The learning of the free electron model of metallic bonding based on the existing knowledge of the simple particle model arguably involves an ontological shift. It has been shown that such a shift might present a big challenge to students (Cheng & Gilbert, 2014).…”

“…However, the process understanding of chemical bonding has been prevalent among some students and has even been suggested in curriculum documents. Also, some students could describe the sequential process of forming the electron sea without indicating the electrostatic force between electrons and cations (Cheng & Gilbert, 2014). It is thus important that such a category of understanding be conceptualized as a possible student understanding.…”

Unpacking students' atomistic understanding of stoichiometry

“…The advantage of using visual cues in combination with verbal cues during chemistry instruction and problem solving has been pointed out in previous research (Cheng & Gilbert, 2014;Sanger & Greenbowe, 2000). Whereas words are coded verbally, students are more likely to code diagrams both verbally and visually.…”