Support materials only that illustrate some possible contexts for exploring Science as a Human Endeavour concepts in relation to Science Understanding content.
Forensic science often relies on chemical processes to analyse materials in order to determine the identity, nature or source of the material (ACSCH052). This requires detailed knowledge of both chemical and physical properties of a range of substances as well as the structure of the materials. Analysis techniques include different forms of chromatography to determine the components of a mixture, for example analysis of urine samples to identify drugs or drug byproducts, identification of traces of explosives, or the presence of an unusual substance at a crime scene. Evidence from forensic analysis can be used to explain the nature and source of samples and predict events based on the combination of evidence from a range of sources (ACSCH053). Calculations of quantities, including the concentrations of solutions, are an essential part of forensic chemistry, as is consideration of the reliability of evidence and the accuracy of forensic tests.
Safe scuba diving requires knowledge of the behaviour of gases with reference to volume, pressure and temperature. In particular, divers should understand how the volume of a gas varies with the surrounding pressure, in order to prevent damage to their respiratory, circulatory and nervous system. Diving equipment is designed to reduce the risk of dealing with gases at high pressure, including both the choice of materials used and the design of systems to improve efficiency and safety (ACSCH052). Guidelines and regulations based on understanding of gas compression and expansion due to changes in water pressure enable divers to avoid conditions such as pulmonary barotrauma and decompression sickness (ACSCH053).
Valence Shell Electron Pair Repulsion (VSEPR) theory is based on an understanding of subatomic and molecular structure and is an extremely powerful tool in the prediction of the shapes of molecules. In 1940 Sidgwick and Powell proposed that the shapes of molecules are dependent on the number of valence electrons in atoms within molecules. This idea was developed further by Australian scientist Sydney Nyholm and Canadian Ronald Gillespie in 1957 to describe how electrostatic repulsion between bonding and/or non-bonding pairs of electrons can be used to reliably predict the shapes of molecules (ACSCH049). They were able to demonstrate a relationship between the internal electronic structure of molecules, as predicted by knowledge of chemical bonding, and the overall shape of the molecules, as revealed by methods such as and X-ray crystallography (ACSCH048). Two- and three-dimensional graphical models have been developed and adopted by chemists to represent and communicate the shapes of molecules (ACSCH048).