This study aimed to examine the impact of years of experience and field of expertise on the development of chemistry knowledge structures from STEM experts comprising 103 professors, 10 postdocs, and 146 doctoral students. Of these participants, 127 were specialized in chemistry and the rest were from various science and engineering disciplines. Although most participants were part of a research university located in Northern California, the pool included a small group of experts from different universities and countries. The main source of the data was a Word Association Test generated with 17 keywords that refer to major topics or concepts commonly introduced in the general chemistry curricula. The knowledge structures were examined to determine if the contents and the orientations of the clusters varied between the expert groups. In addition, their analysis was enriched with the consideration of chemistry triplet designations and central terms identified by eccentricity values on each structure. The overall expert knowledge structure generated in this study was also compared to undergraduate structures determined by using the same instrument and methodology. The investigation of the structures revealed several differences between expert groups and provided insight into the transformation of novices into experts. The paper also presents practical suggestions for educators on how to utilize structures while teaching, informing their instructional practices, and reforming teaching materials.

Concept maps are powerful tools used to reveal challenges in students' learning. However, their use introduces complexities when a large group of students' conceptualizations need to be examined. In this study, concept maps of 344 general chemistry students were analyzed after grouping them based on achievement in chemistry, math proficiency, and gender. The analysis was also expanded with the consideration of eccentricity values and the extended chemistry triplet. Although some similarities exist between the map of high-achieving students in chemistry and that of high-performing students in the Mathematics Placement Test (MPT), the calculated eccentricity values show interesting variations. On the other hand, the analysis of the map of the low-performing students in MPT and that of low-achieving students in chemistry revealed no clear patterns of symbolic, macroscopic, and submicroscopic terms. Practical suggestions were included to increase the use of representative maps in different assessment and teaching scenarios.