Background:
Comprehending the subjects and concepts of chemistry requires that students understand the related concepts and ideas, which in turn, develops compatible and consistent knowledge structures. In other words, students need to prefer meaningful learning instead of rote learning so that they can build a well-organised conceptual framework.

Material and methods:
Semi-structured interviews were conducted with the participants and the interviews were audio recorded to prevent the loss of data. The data were transcribed and transferred into the computer medium. A flow map was prepared for each participant and then was analysed in terms of quantitative variables.

Results:
In consequence, it was found through flow maps that participants were not very different from each other in terms of cognitive structure and that their cognitive structures were full of inadequacies and misconceptions. Having analysed the statements in the flow maps in terms of the comprehension level, the scope and richness of participants’ cognitive structures were exhibited in more details.

Conclusions:
According to the findings, prospective chemistry teachers use some incomplete knowledge structures while making explanations on covalent and ionic bonding. In other words, they make explanations by setting up connections between some knowledge fragments that can be regarded as nonoperational definitions of chemical bonding.