“Forces and interaction between substances” is the central focus of this unit, including both concepts of chemical bonding and chemical reaction. The goal is to point out and develop the relevance of explaining properties and behaviour of substances as an interaction of the substance in a certain environment.

This principle is not only important for chemists but also for an understanding of phenomena and products in daily-life and industrial contexts. That is why a large number of activities in all of the three subunits deal with everyday substances, such as household cleaners or textiles/clothes. From this students can see that they are able to explain “trivial” processes such as drying their sport jacket on the radiator on a chemical basis.