C2.3 Properties of materials
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C2.3 Properties of materials
Mathematical learning outcome:
CM2.3i represent three-dimensional shapes in two dimensions and vice versa when looking at chemical structures e.g. allotropes of carbon
Assessable content statements:
C2.3a recall that carbon can form four covalent bonds
C2.3b explain that the vast array of natural and synthetic organic compounds occur due to the ability of carbon to form families of similar compounds, chains and rings
C2.3c explain the properties of diamond, graphite, fullerenes and graphene in terms of their structures and bonding
C2.3d use ideas about energy transfers and the relative strength of chemical bonds and intermolecular forces to explain the different temperatures at which changes of state occur
C2.3e use data to predict states of substances under given conditions
C2.3f explain how the bulk properties of materials (ionic compounds; simple molecules; giant covalent structures; polymers and metals) are related to the different types of bonds they contain, their bond strengths in relation to intermolecular forces and the ways in which their bonds are arranged
This section deals with the macroscopic properties of materials arising from their structure. Learners should be led to understanding that what we can see or measure in terms of physical shape and properties is a reflection of the nature of the bonding within each substance.
Chemists, in making substances useful to society, exploit these qualities. This is particularly the case with compounds containing carbon. Carbon’s ability to bond to itself and a wide range of other elements using single, double and triple bonds producing a huge range of useful products is the basis of organic chemistry and learners should realise its importance.
Learners should be made aware of the importance of Nanochemistry and the fact that this is not the only preserve of carbon chemistry, that there a wider range of Nano-particles e.g. use of gold and ZnO . They should also be aware not only of the benefits but also the potential dangers of their use. This is such a fast moving area of science that it should be researched by the learners as an activity.
Common misconceptions or difficulties learners may have
The fact that changes of state encompasses both bond breaking and the weakening of intermolecular forces gives rise to confusion, especially when linking changes of state in covalent molecules.
Conceptual links to other areas of the specification – useful ways to approach this topic to set learners up for topics later in the course
Learners with a sound understanding of the nature of changes of state can better explain the differences in boiling point encountered in the fractional distillation of crude oil.
Relating particle size by means of surface area to volume ratios, links to rates of reaction versus surface area of reactant; also the use of Nano-particles as support for catalysts.
Approaches to teaching the content
Learners should be aware from Key Stage 3 that carbon atoms can bond to each other as well as other elements to form up to four bonds per atom of C. This leads not only to a huge range of possible substances but also to a large number of allotropes (C2.3a, C2.3b and C2.3c). The NBC video covers the discovery of the latest two of the latter and some of their impact on materials science (C2.3c).
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