Understanding the nature and purpose of models, including mathematical models, is critical to enabling undergraduate chemistry students to use models to predict and explain phenomena. However, students often do not have systematic conceptions about different kinds of models. To gain a sense of how students understand different models in the general chemistry curriculum, we developed a survey to examine students' reasoning about models generally and in some specific contexts within the general chemistry curriculum. The findings suggest that students have some productive ideas about what kinds of representations are scientific models and the characteristics of those models; however, students may not recognize these characteristics in models which are mathematical or graphical in nature.