Reactivity and Further Chemical Reactions

Some metals are keener than others

Metals do not all react in the same way. Some, like potassium and sodium, react violently even with cold water, while others, like gold, barely react at all. Chemists put metals in order of how eager they are to react, and this list is called the reactivity series. Knowing the order lets you predict a great deal: which metal will react faster, whether one metal can push another out of a compound in a displacement reaction, how quickly a metal will corrode, and even how the metal must be extracted from the ground. This module covers the reactivity series, how reactive and unreactive metals behave, displacement, and how reactivity decides the method used to extract each metal.

Reactivity words

Learn these five terms before you rank and react the metals.

Match each metal behaviour to what happens

Reactive against unreactive metals

Where a metal sits in the series shapes how it behaves and how we use it.

Which metal wins?

A strip of magnesium is placed in a solution of copper sulfate. Magnesium is more reactive than copper. What happens?

• The magnesium displaces the copper from the solution
• The copper displaces the magnesium
• Nothing happens at all
• The solution freezes solid

Reactivity decides how we extract a metal

How a metal is taken from the ground depends entirely on how reactive it is. The most reactive metals hold on to their compounds so tightly that only electricity can pull them apart, which is why metals such as sodium and aluminium are extracted by passing a current through them. Metals in the middle of the series, such as iron, can be freed by heating their ore with carbon, which is cheaper. The least reactive metals, such as gold, react so little that they are often found in the ground already as the pure metal, needing no chemical extraction at all. So before you can say how a metal is obtained, you first have to know where it sits in the reactivity series.

Pick the true facts about reactivity

Select every statement about the reactivity of metals that is true.

• The reactivity series lists metals in order of reactivity
• A more reactive metal can displace a less reactive one
• Very reactive metals are extracted using electricity
• Gold is one of the most reactive metals
• All metals react with water at exactly the same rate

Order these metals by reactivity

Put these metals in order from the most reactive at the top to the least reactive at the bottom.

• potassium
• magnesium
• zinc
• iron
• copper

Complete the reactivity facts

A list of metals in order of how reactive they are is the reactivity _____. A reaction where a more reactive metal takes the place of a less reactive one is a _____ reaction. Getting a metal out of its compound is called _____. A very reactive metal is extracted using _____.

A pecking order in the yard

Think of the pecking order among a flock of hens in a yard. Each hen knows which others it can push aside and which it must give way to, so there is a clear ranking from the boldest bird right down to the meekest. If a bolder hen wants the best feeding spot, it simply moves a timider one out of the way and takes it. Metals behave in much the same way. Some are bold and eager, quick to react and able to shove a quieter metal out of a compound and take its place, while others are so mild they barely react at all. Once you know the ranking, you can predict which metal will come out on top whenever two of them meet, and why the quiet ones are the last to change.

Tap the reactive metals

Tap every metal below that is highly reactive, near the top of the series.

• potassium
• sodium
• magnesium
• gold

The reactivity run

Answer each one correctly to keep your lives. Choose the best answer.

Predict the reaction

Read each situation and choose the best answer.

• You put a strip of iron into a solution of copper sulfate. Iron is more reactive than copper. What happens?
• You need to extract a very reactive metal from its ore. Which method suits it?
• You want a metal for jewellery that will not corrode over time. Which kind is best?

Build a reactivity point

Choose the word for each gap to complete one accurate point about the reactivity of metals.

Explain reactivity and metal reactions

A friend does not see why some metals react so differently from others. Explain the reactivity of metals clearly.

• Explain what the reactivity series is
• Explain how reactive and unreactive metals behave differently
• Explain what a displacement reaction is, with an example
• Explain how reactivity affects the way a metal is extracted
• Explain why unreactive metals are useful for lasting objects