A concept commonly used by both teachers and students is the term "chemical." Many students and teachers think of chemicals as artificial, poisonous, and dangerous. The purpose of the study was to investigate science teachers' ideas about "chemicals," along with their awareness of students' alternative conceptions and teaching practices that attempt to address alternative conceptions. Two main data sources were used: chemical surveys completed by 43 science teachers and interviews with nine chemistry teachers. Both surveys and the interviews were analyzed qualitatively to discern themes in teachers' conceptions of "chemicals" and its teachability. Survey analysis yielded four categories for teachers' conceptions: (a) sound understanding; (b) coherent alternative conception; (c) inconsistent views; or (d) vague ideas. A most prominent finding from interviews was that, except for one teacher, all chemistry teachers either provided a correct definition of the term "chemical" from the beginning or eventually articulated it as the interview progressed, with three teachers changing their statements during the interview. All of the teachers except one were aware that their students have some kind of alternative conceptions. The teachers suggested a few possible sources of students' alternative conceptions, such as lack of relevancy of material in chemistry courses, insufficient expositions to chemistry courses, and faulty usage of the term in everyday language and the media. The teachers' suggestions for addressing alternative students' conceptions were varied. The nature of teachers' conceptions is discussed as dynamic. Implications such as the use of dialog and word reflection for problematic scientific terms by teachers are presented and discussed. (Contains 1 figure, 2 tables and 2 notes. Appended are: (1) Interview Guide I; and (2) Interview Guide II.)