This phenomologic study was carried out in order to determine how 63 pre-service chemistry teachers graduated from Chemistry Branch of Science Faculty in the pedagogical training program during 2013-2015 academic years defined the concepts of density and melting and boiling points and how they interpreted the data in micro levels. A diagnostic instrument for measurement consisting of six open-ended questions was prepared. Content analysis was performed and the results were given in frequency and percentage distribution category. Below 50% of participants gave significant and correct answers to all of the questions about density, melting and boiling points and they interpreted the concepts of underlying data and units in micro levels correctly. It was established that most of the students could not go beyond formulas especially in the concept of density and they had misconceptions about the definitions of this concept and interpretation of the data related to density, melting and boiling points. Given the students' answers, it can be stated that the misconceptions that were associated with the research concepts resulted from the misconceptions of preservice teachers about particle size, particle mass and intermolecular forces. It can be quite useful to present the practices of employing data and units for significant science education to students' attention during all stages of teaching.