Between 1970 and 1990, the Dutch working group "Empirical Introduction to Chemistry" developed a secondary school chemistry education curriculum based on the educational vision of the mathematicians van Hiele and van Hiele-Geldof. This approach viewed learning as a process in which students must go through discontinuous level transitions characterized by linguistic changes. Transposed to chemistry education, the first transition is from the ground level to the descriptive level, where students learn to describe regularities in chemical phenomena. This transition is followed by a transition to the theoretical level, where students learn the structure of these regularities. In this article, the researchers introduce the qualitative concept of "chemical element", expand it to address quantitative formulas for gases, and explain it using the concept "chemical atom" as an indivisible unity. The researchers qualitatively analyze transcripts of discussions both between students and between students and their teacher to look for evidence of chemistry learning in accordance with the theoretical expectations. The results show the applicability of the Van Hiele theory of level transitions for chemistry learning. In retrospect, more attention should have been paid to necessary idealizations to arrive at the desired chemical concepts.