Within this topic, students can consider the strengths and weaknesses of the models used to describe different types of bonding. As part of their study of electron-pair repulsion theory, students can see how chemists can make generalisations and use them to make predictions.

Within this topic, students can consider how oxidation number provides a more considered route for the process of balancing chemical equations.

Within this topic, students can consider how data can be used to make predictions based on patterns and relationships, for example, by predicting properties of Group 7 elements.

Within this topic, students first encounter core practicals and can consider ideas of measurement uncertainty, evaluating their results in terms of systematic and random errors. They can also consider how the concept of atom economy is useful to help chemists make decisions so that reactions can be made more efficient regarding resources.

Within this topic, students can consider how the polymer industry provides useful solutions for many modern applications but poses questions about resource sustainability and the feasibility of recycling. They will also encounter practical organic chemistry, which will show them how chemists work safely with potentially hazardous chemicals by managing risks.

Within this topic, students can consider how different instrumental methods can provide evidence for analysis. They can see how accurate and sensitive analysis methods can be applied to the study of chemical changes and detect drugs such as in blood or urine testing in sport.

Within this topic, students can consider how Hess’s Law can facilitate the study of energy changes in reactions that are not directly measureable. They can also consider the value of a general chemical concept, such as mean bond enthalpy, and why the use of a simplification such as this has some benefits as well as some shortcomings.

Within this topic, students can consider how the use of models in chemistry is illustrated by how the Maxwell-Boltzmann distribution and collision theory can account for the effects of changing variables on the rate of a chemical reaction.

Within this topic, students can consider how an appreciation of equilibrium processes and kinetics can lead chemists to redevelop manufacturing processes to make them more efficient.

Within this topic, students can consider how chemists can use equilibria to predict the direction and extent of chemical change quantitatively.

Within this topic, students can consider how the historical development of theories explaining acid and base behaviour shows that scientific ideas change due to new evidence and fresh thinking. They can also relate their study of buffer solutions to various applications in living cells, medicines, foods and the natural environment.

Within this topic, students can consider how chemists evaluate theoretical models by comparing the real and ideal properties of chemicals, for example, in studying theoretical and experimental lattice energies. The study of entropy shows students how chemists use formal, abstract thinking to answer fundamental questions about the stability of chemicals and the direction of chemical change.

Within this topic, students can consider how ideas developed in different contexts within chemistry can be shown to be related to a major explanatory principle. Here, cell EMFs and equilibrium constants are related to the fundamental criterion for the feasibility of a chemical reaction: the total entropy change. Students can also consider how chemists continue to search for alternative sources of energy through the development of fuel cells.

Within this topic, students can consider the model for filling electron orbitals encountered in Unit 1 and see how limitations in that model indicate the need for more sophisticated explanations. They can also appreciate that catalyst research is a frontier area and one which provides an opportunity to show how the scientific community reports and validates new knowledge.

Students can consider different methods used to measure reaction rates and collect valid data on this topic. Through the analysis of this data and knowledge of rate equations, they can see how chemists can propose models to describe the mechanisms of chemical reactions.

In this topic, students can consider how organic synthesis can produce various important materials, such as esters for solvents, flavourings, and perfumes. They will also continue their study of reaction mechanisms and see how different mechanisms act as a pattern to describe a range of organic reactions.

Within this topic, students can consider how the model for benzene structure has developed in response to new evidence. By this stage, their continuing practical experience should enable them to use techniques to conduct reactions and purify products efficiently and safely.

Within this topic, students can consider a wider range of instrumental methods used for analysis, such as NMR; and see how this technique is used in medicine through MRI scans. They can also see a wide range of applications that rely on various analytical techniques.