In this deck, we'll explore chemical changes. You'll learn about the reactivity of metals and how this determines how they are extracted from their ores. We'll cover the reactions of acids, the meaning of the pH scale, and the difference between strong and weak acids. Finally, we'll investigate electrolysis, a process that uses electricity to break down compounds. This deck also covers the methods for two required practicals: making a soluble salt and the electrolysis of aqueous solutions.

Some metals are much more reactive than others. For example, potassium reacts explosively with water, while gold can be found unreacted in the ground for thousands of years. Scientists have arranged metals in order of their reactivity, from most reactive to least reactive. This is called the reactivity series. A simple version to remember is: Potassium, Sodium, Calcium, Magnesium, Aluminium, Carbon, Zinc, Iron, Lead, Hydrogen, Copper, Silver, Gold. Notice that carbon and hydrogen are included, as they are useful comparison points for metal extraction and acid reactions.

The reactivity series allows us to predict what will happen when a metal is placed in a solution containing the salt of another metal. A more reactive metal will displace, or push out, a less reactive metal from its compound. For example, if you place a piece of iron into a solution of blue copper sulfate, the more reactive iron will displace the copper. You would see the iron get coated with brown copper metal, and the blue solution would fade as iron sulfate is formed.