Many studies of college chemistry students have found a gap between students' success in solving computational chemistry problems and their success in solving conceptual chemistry problems. This paper examines college students' understanding of the concept of stoichiometry, the particulate nature of matter, and chemistry problem solving. This study closely examined student learning and application of chemistry knowledge, both conceptual and computational, in an attempt to closely examine the disparity between conceptual and computational understanding. The results of this study have implications for science education at all levels, but specifically apply to undergraduate chemical education. Science educators must help students make the connections between the concepts of science and applications of those concepts. This study highlighted areas where those connections can be reinforced; an understanding of the particulate nature of matter and the models used to illustrate that nature; connections between the macroscopic, microscopic, and symbolic levels of chemistry; and completing the cycle of understanding by emphasizing conceptual understanding in the course assignments and assessments. (CCM)