ABSTRACT
Chemistry is fundamentally the science that studies the properties of substances, including how they interact. Some familiar materials are effectively single substances: diamonds, table salt, baking soda, aluminium foil. The idea of a substance is a concept relating to the theoretical redescriptions of phenomena observed at the macroscopic level: this yellow stuff is the substance sulphur; these white grains are the substance sucrose; those white crystals are the substance sodium chloride; etcetera. The ‘substance’ concept is a prerequisite for understanding other core chemical concepts such as ‘element’ and ‘compound’ and ‘chemical reaction’. By contrast, a well-stocked chemical cupboard may contain a wide range of pure substances, and it is these that are the usual focus of laboratory work in school chemistry. For most of the substances found in chemistry laboratories, preparation involves chemical processes, and the substance is not simply extracted from a complex natural source by separation techniques.
