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Recent research on the phenomenon of improper proportional reasoning focused on students' understanding of elementary functions and their external representations. So far, the role of basic function properties in students' concept images of functions remained unclear. We add to this research line by investigating how accurate students are in connecting functions to their corresponding properties and how this accuracy depends on function types and representations. A large group of 10th graders evaluated for different function types, represented in either a graphical, a formulaic, or a tabular mode, the correctness of statements about their general properties and behavior. Results show that students succeeded rather well in making the right connections between properties and functions. Errors depended not only on the type of function for which the properties were evaluated but also on the kind of representation in which the function was presented. These results highlight the importance of function properties in students' concept images of functions and suggest positive effects of making these properties explicit to students.