Topic 1 What is a Chemical reaction?

A chemical reaction is the process of rearranging atoms between substances to form new compounds with different properties. When compounds or elements react, they are transformed into one or more different substances.

The substances that react are called reactants and the substances that are generated are called products. The chemical reaction is represented by a chemical equation, where the reactants are placed to the left of an arrow followed by the products to the right.

How do we know that reactions occur?

We can tell that a reaction is taking place because we see a change in the environment:

  • Bubbles appear
  • There is a heat exchange (It cools or heats).
  • Light appears
  • A solid appears
  • A smell appears
  • There is a colour change