IS THE ATOM REAL OR BUILT? OR IS IT AN INTERMEDIATE BETWEEN THESE TWO? A WITTGENSTEINIAN APPROACH. Jackson Gois 1,2 and Marcelo Giordan 2 1 Department of Chemistry – Universidade Federal do Paraná – Brasil 2 Faculty of Education – Universidade de São Paulo – Brasil Abstract: The question about whether the atom is real or built is still among us despite the scientific and philosophical efforts already made. In this work we propose a solution to this question based on the philosophy of Wittgenstein, looking on how we use language. Wittgenstein’s thought is considered of crucial importance in twenty century philosophy. Despite the importance of his philosophy, which helps us to think about concepts, language and meaning, nowadays there are few contributions of Wittgenstein’s ideas in science education. We challenge the idea of asking questions directly about the atom out of a model and try to put real and building in the right place in scientific practice. We discuss about models, data and natural phenomena, and try to understand them in terms of real and built. Instead of trying to answer this question, we dissolve it, remembering what exists and what is built in scientific practice. Wittgenstein’s philosophy, as an exercise to a closer look on how we use language, is useful to understand philosophical aspects of chemistry and science education. We must not fear or be angry with either existence or building. It is only necessary to put each one of them in their right place. We think it is an interesting educational solution to this problem, as students will start to see that some usual questions may be illusory. Keywords: Wittgenstein, Science Teaching, realism, constructivism, philosophy of language INTRODUCTION It is quite clear by now that Wittgenstein (2001) wrote about philosophy, more specifically the language illusions that philosophers had been chasing for some centuries thinking it were big truths. Wittgenstein’s thought is considered of crucial importance in twenty century philosophy. His contribution has influenced the linguistic turn in philosophy and also many other disciplines. These contributions, like his anti-essencialist approach and his methods of pointing to language illusions where philosophers have been trying to find grounds, are still a challenge to those dedicated to an in deep understanding of his thought. His important philosophy helps us to think about concepts, language and meaning, and nowadays the contributions of Wittgenstein’s ideas in Science Education research can be found in influential epistemologies inspired on his philosophy (Wickman and Östman, 2004). The questions about the existence of the atom are important in chemistry courses and teacher training courses. Our main focus is to present a contribution on this subject based on Wittgenstein’s philosophy. As well as the philosopher, we want to show that some expressions in Chemistry and Science Education are misleading, and have guided us to ask