We investigated students’ knowledge constructions of basic quantum chemistry concepts, namely, atomic orbitals, the Schrφdinger equation, molecular orbitals, hybridization, and chemical bonding. The theory of meaningful learning provided the theoretical framework and phenomenography the method of analysis. The semi-structured interview with nineteen second-year chemistry students supplied the data. We identified four levels of explanations in the students’ answers. In addition, the scientific knowledge claims reflected three main levels of models. By combining levels of explanations with levels of models, we derived four categories. Two of the categories are two shades of variation in the rote-learning edge of a continuum, while the other two categories are in the meaningful-learning edge.