(abstract and paper still missing)

In this paper, one student's learning process in a course on quantum atomic physics in grade 13 of a German gymnasium (secondary school) is described. The course lasted 16 weeks for a total of approximately 80 lessons. The aim of the present study is to elaborate the student's cognitive system for atomic physics as a hypothetical pragmatic model to describe, analyse and explain his thinking and learning sequence of several meta-stable conceptions of the atom, starting from a planetary model.