Predicting chemical reactions

C4.1 Predicting chemical reactions

Summary Models of how substances react and the different types of chemical reactions that can occur enable us to predict the likelihood and outcome of a chemical reaction. The current Periodic Table was developed based on observations of the similarities and differences in the properties of elements. The way that the Periodic Table is arranged into groups and periods reveals the trends and patterns in the behaviour of the elements. The model of atomic structure provides an explanation for trends and patterns in the properties of elements. The arrangement of elements in groups and periods reveals the relationship between observable properties and how electrons are arranged in the atoms of each element. Underlying knowledge and understanding Learners should be familiar with the principles underpinning the Mendeleev Periodic Table; the Periodic Table: periods and groups; metals and non-metals; the varying physical and chemical properties of different elements; the chemical properties of metals and non-metals; the chemical properties of metal and

non-metal oxides with respect to acidity and how patterns in reactions can be predicted with reference to the Periodic Table. Common misconceptions Learners consider the properties of particles of elements to be the same as the bulk properties of that element. They tend to rely on the continuous matter model rather than the particle model. Learners confuse state changes and dissolving with chemical changes. Also, since the atmosphere is invisible to the eye and learners rely on concrete, visible information, this means learners often avoid the role of oxygen in their explanations for open system reactions. Even if the role of oxygen is appreciated, learners do not realise that solid products of an oxidation reaction have more mass than the starting solid.