The Reactivity Series

Your loss is my gain

Rust forms on iron and steel as a result of a redox reaction between iron and oxygen.

Oxidation and reduction reactions are very commonplace. When a element combines with oxygen that element is said to have been oxidised.

When the oxygen is removed from an oxide of an element to leave the element on its own, the oxide is said to have been reduced.

Here we will use broader definition of oxidation and reduction which considers the loss and gain of electrons.

Oxidation Is the Loss (of electrons) Reduction Is the Gain (of electrons) 

f. Students will be assessed on their ability to:

2.29 understand that metals can be arranged in a reactivity series based on the reactions of the metals and their compounds: potassium, sodium, lithium,calcium, magnesium, aluminium, zinc, iron, copper, silver and gold
2.30 describe how reactions with water and dilute acids can be used to deduce the following order of reactivity: potassium, sodium, lithium, calcium,magnesium, zinc, iron and copper
2.31 deduce the position of a metal within the reactivity series using displacement reactions between metals and their oxides, and between metals and their salts in aqueous solutions
2.32 understand oxidation and reduction as the addition and removal of oxygen respectively
2.33 understand the terms redox, oxidising agent, reducing agent
2.34 describe the conditions under which iron rusts
2.35 describe how the rusting of iron may be prevented by grease, oil, paint,plastic and galvanising
2.36 understand the sacrificial protection of iron in terms of the reactivity series

A helpful mnemonic. Remember it refers to loss and gain of electrons!

A simple displacement reaction 

This video explains the reaction when copper metal is displaced from solution by the more reactive metal iron. An iron nail is placed in a solution of copper sulphate.

  • iron is more reactive than copper
  • iron displaces the copper from solution
  • copper ions are reduced ( gain electrons)  to become copper atoms
  • iron atoms are oxidised to iron ions
Iron atoms are more reactive than copper. Iron displaces copper ions from the solution.

A question of reactivity 

You can use the reactivity series to predict what will happen when a solid sample of one metal is placed in a solution of another metal

Give and take... 

 Half equations can be used to show what happens to each type of particle involved:

Iron atoms lose electrons and are therefore oxidised to ions
Copper ions gain electrons and are therefore reduced to atoms

Video Exercise: Metal displacement reactions close up..

This video shows a number of metal displacement reactions magnified and speeded up. For each reaction in turn:

  • decide which metal is oxidised
  • decide which metal is reduced
  • write two half equations to represent these changes
  • use these equations to decide the order of reactivity of lead, silver, copper and zinc