The Reactivity Series (AQA GCSE Chemistry: Combined Science)

• Based on how they react with other substances, a reactivity series can be produced in which the metals are placed in order of their reactivity
• Metal atoms form positive ions by loss of electrons when they react with other substances
• The tendency of a metal to lose electrons is a measure of how reactive the metal is
• A metal that is high up on the series loses electrons easily and is thus more reactive than one which is lower down on the series
• Note that although carbon and hydrogen are non-metals, they are included in the series as they are useful in extracting metals from their oxides by reduction processes

Diagram of the reactivity series of metals

• There are several reactivity series mnemonics to help you remember the order of the metals
• One that we like goes as follows: “Please send lions, cats, monkeys and cute zebras into hot countries signed Gordon”

Reactivity series mnemonic table

Metal	Abbreviation
Most reactive
Potassium	P - Please
Sodium	S- Send
Lithium	L - Lions
Calcium	C - Cats
Magnesium	M - Monkeys
Aluminium	A - And
Carbon	C - Cute
Zinc	Z - Zebras
Iron	I - Into
Hydrogen	H - Hot
Copper	C - Countries
Silver	S - Signed
Gold	G - Gordon
Least reactive

You can learn the reactivity series with the help of a silly phrase

Chemical properties of metals

• The chemistry of metals is studied by analysing their reactions with water and dilute acid

Metals reacting with water

• Some metals react with water
• Metals above hydrogen in the reactivity series will react with water
  • For some metals such as iron, the reaction may be very slow
  • For other metals such as the alkali metals, the reaction may be quick and potentially hazardous because of their reactivity
• Metals that react with cold water form a metal hydroxide and hydrogen gas:

metal + water → metal hydroxide + hydrogen

• For example, calcium:

Ca       +    2H₂O     → Ca(OH)₂      +      H₂

calcium + water → calcium hydroxide + hydrogen

• Magnesium reacts very slowly with cold water when finely divided
• Magnesium reacts with gaseous water to form a metal oxide and hydrogen gas:

Mg       +    H₂O     → MgO      +      H₂ 

magnesium + water → magnesium oxide + hydrogen

Reactions of metal with cold water summary table

Metal	Reaction with water
Most reactive
Potassium	Reacts violently
Sodium	Reacts quickly
Lithium	Reacts less strongly
Calcium	Reacts less strongly
Magnesium
Zinc
Iron	Slow rusting
Copper
Least reactive

The Group 1 metals are reactive with water, Group 2 metals are less reactive and other metals are generally unreactive with water

Metals reacting with acid

• Most metals react with dilute acids such as HCl
• Only the ones below hydrogen in the reactivity series will not react with acids
• When acids and metals react, the hydrogen atom in the acid is replaced by the metal atom to produce a salt and hydrogen gas:

metal + acid → metal salt + hydrogen

• For example iron:

Fe    +     2HCI    →    FeCl₂    +    H₂

iron + hydrochloric acid   →  iron(II)chloride + hydrogen

• In both these types of reactions (water and acids) the metals are becoming positive ions
• The reactivity of the metals is related to their tendency to become an ion
• The more reactive the metal the more easily it becomes an ion (by losing electrons)

Reactions of metal with dilute acid summary table

Metal	Reaction with dilute acid
Most reactive
Potassium	Reacts violently
Sodium	Reacts violently
Lithium	Reacts vigorously
Calcium	Reacts vigorously
Magnesium	Reacts vigorously
Zinc	Reacts less strongly
Iron	Reacts less strongly
Copper
Least reactive

The Group 1 metals are reactive with water, Group 2 metals are less reactive and other metals are generally unreactive with water

• The reactivity of metals decreases going down the reactivity series.
• This means that a more reactive metal will displace a less reactive metal from its compounds
• Two examples are:
  • Reacting a metal with a metal oxide (by heating)
  • Reacting a metal with an aqueous solution of a metal compound

• For example, it is possible to reduce copper(II) oxide by heating it with zinc.
• The reducing agent in the reaction is zinc:

Zn    +     CuO    →    ZnO    +    Cu

zinc + copper oxide → zinc oxide + copper

Metal oxide displacement table

Mixture	Products	Equation for Reaction
Iron(III) oxide and aluminium - thermite reaction	Iron and aluminium oxide	Fe2O3 + 2Al  → 2Fe + Al2O3
Sodium oxide and magnesium	No reaction as sodium is above magnesium	-----
Silver oxide and copper	Silver and copper(II) oxide	Ag2O + Cu → 2Ag + CuO
Zinc oxide and calcium	Zinc and calcium oxide	ZnO + Ca → Zn + CaO
Lead(II) oxide and silver	No reaction as lead is more reactive than silver	------
Iron nail and copper(II) chloride	Copper and iron(II) chloride	Fe + CuCl2 → FeCl2 + Cu

Thermite

• The thermite reaction is a highly exothermic reaction that occurs when iron(III) oxide is reacted with aluminium metal
• As aluminium is more reactive than iron, the iron in iron(III) oxide is displaced 

iron(III) oxide + aluminium → iron + aluminium oxide

Fe₂O₃ + 2Al → 2Fe + Al₂O₃

• The reaction releases so much heat that the iron formed is molten so this process is used in welding and incendiary devices

Displacement reactions between metals & aqueous solutions of metal salts

• The reactivity between two metals can be compared using displacement reactions in salt solutions of one of the metals
• This is easily seen as the more reactive metal slowly disappears from the solution, displacing the less reactive metal
• For example, magnesium is a reactive metal and can displace copper from a copper sulfate solution:

Mg + CuSO₄  →  MgSO₄ + Cu

• The blue colour of the CuSO₄ solution fades as colourless magnesium sulfate solution is formed.
• Copper coats the surface of the magnesium and also forms solid metal which falls to the bottom of the beaker

Diagram showing the colour change when magnesium displaces copper from copper sulfate

Other displacement reactions

Metal solutions displacement table

Mixture	Products	Equation for Reaction
Magnesium and iron(II) sulfate	Magnesium sulfate and iron	Mg + FeSO4 → MgSO4 + Fe
Zinc and sodium chloride	No reaction as sodium is above zinc	------
Lead and silver nitrate	Lead(II) nitrate and silver	Pb + AgNO3 → Pb(NO3)2 + Ag
Copper and calcium chloride	No reaction as calcium is above copper	-------
Iron and copper(II) sulfate	Iron(II) sulfate and copper	Fe + CuSO4 → FeSO4 + Cu