From the Beginnings to the Nineteenth Century

Abstract

AbstractIn addition to the development of the terms “atom”, “element” and “molecule” this chapter is devoted to the fundamental chemical and physical laws which, from the seventeenth century onwards, eventually led to Avogadro's hypothesis. The conclusions culminate in the universal gas equation. Explanations of the origin of the term “mole” close the chapter.It was a long way until Avogadro came on the scene with his hypothesis (compare Sect. 2.2.10) and until atoms were recognised as real entities. Thus Goethe lets his Faust say in Chap. 4 of the first part of the tragedy: „Dass ich nicht mehr mit saurem Schweiß // Zu sagen brauche, was ich nicht weiß // Dass ich erkenne, was die Welt // Im Innersten zusammenhält.“ (“That I no longer need in sour sweat // To say what I do not know // That I recognize what holds the world // Together in its innermost.”).And many naturalists felt the same way as Faust. They wanted to understand, recognize, experience “the innermost of things”. With the Greek philosophers, this was still done purely by thinking, but in later times, targeted experiments and measurements were added.Let’s first look at how the concepts of atom, molecule and element have evolved. After that you will learn important regularities so as to finally arrive at the Avogadro constant.