Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.
Over 80 per cent of all known compounds are organic compounds. Initial work in the area of organic chemistry was based on observational chemistry, with nineteenth century attempts to organise the diversity of organic compounds based on grouping them according to their reactions. This theory was primarily based on empirical observations of reactivity, and did not consider the structure of the compounds. The theory of chemical structure was initially evident in work describing the concept of the interatomic bond, as formulated independently and simultaneously by Kekulé and Couper in 1858 (ACSCH121). Further advances in understanding of the chemical structure of carbon-based molecules led to a classification based on functional groups. The chemical behaviour of the molecule can now be predicted based on known chemistry of the functional groups it contains. Developments in computer modelling have enabled more accurate visualisation and prediction of three dimensional organic structures, such as proteins, which is critical in drug design and biotechnology (ASCSH120).
Polymers are common in daily life due to their extraordinary range of properties, and include natural polymeric materials such as wool, silk and natural rubber, and synthetic polymers such as synthetic rubber, neoprene, nylon, polystyrene and polypropylene. Contemporary applications of polymers include their use in organic light emitting diodes (OLEDs) to develop television, computer and mobile phone screens that are lighter, more flexible and more energy efficient than previous materials. Synthetic polymers often have large “ecological footprints” as they are synthesised from fossil fuels and do not biodegrade. There is significant research and development directed towards sustainable polymers, produced from renewable sources such as plants, waste products and waste gases (ACSCH126). While there have been significant advances in this field, issues remain regarding the economic viability of this means of production, and use of food crops for the production of polymer materials rather than food (ACSCH122).
Organochlorine compounds, such as DDT, chlordane and lindane, were identified as powerful insecticides in the 1950s and their use was credited with reducing malaria and increasing agricultural productivity. Their structure makes them chemically unreactive, so they are stable in soils and in the fatty tissues of animals. As such, they are persistent organic pollutants (POPs), accumulating in food chains and posing a risk of causing adverse effects to human health and the environment. The detrimental environmental effects of DDT were first hypothesised by scientists in the 1940s; when they were popularised through a best-selling book, Silent Spring, in 1962, public reaction was sufficiently large to prompt a government investigation (ACSCH123). Consequently DDT was banned by the United States in 1972, and in 1995 POPs were identified as an issue requiring global action by the United Nations, resulting in a range of organochlorine compounds being banned for agricultural use worldwide under the Stockholm Convention in 2001 (ACSCH125). However some organochlorine compounds are still licensed for use under strict guidelines. For example, they are used to control fire ants, which are a serious social, economic and environmental threat in Australia, the Philippines, Taiwan and parts of New Zealand (ACSCH125).