From Dalton to Lavoisier, the way chemists have represented chemical change has evolved over time.

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Many students have difficulty perceiving a chemical reaction as a dynamic process.

This is sometimes not helped by the way in which they learn about these changes. Often they are presented with chemical formulae before they have fully grasped what might be taking place on an atomic level. Consequently misconceptions can arise.

For example the animation shows carbon dioxide forming from carbon and oxygen:

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Key points

What do you think the key learning is here?

Students need to understand that a chemical equation is a summary of what has been or is taking place.

What might be the benefit of using molecular models or animations?

Students need to be encouraged to think about what is taking place at a molecular/atomic level.

What should we teach students to ensure they understand the steps involved in chemical change?

In order to tackle difficulties encourage pupils to use models to show:

• breaking of bonds
• reorganisation of atoms
• formation of new bonds

What can the chemical equation be used to summarise?

The chemical equation can be used to summarise the changes. This could then be used in parallel with the burning of carbon in the presence of oxygen to encourage links to be made to the sub-microscopic world.

A symbolic tool has been designed to help students shift their thinking between what they can see (macroscopic level) and the explanatory models to understand observations (sub-microscopic level). This is explored further within the Quantitative chemistry course where full examples and formative check questions are provided. To access this you will need to subscribe to it as a separate course.