Reactivity Series (Cambridge (CIE) IGCSE Combined Science): Revision Note

Reactivity series

What is the reactivity series of metals?

• The chemistry of the metals is studied by analysing their reactions with water and acids

• Based on these reactions a reactivity series of metals can be produced

• The series can be used to place a group of metals in order of reactivity based on the observations of their reactions with water and acids

• The non-metals hydrogen and carbon are also included in the reactivity series as they are used to extract metals from their oxides

Reactivity series order

• The order of the reactivity series is:

  • Potassium

  • Sodium

  • Calcium

  • Magnesium

  • Aluminium

  • Carbon (non-metal)

  • Zinc

  • Iron

  • Hydrogen (non-metal)

  • Copper

  • Silver

  • Gold

How to remember the reactivity series

• The order of this reactivity series can be memorised using the following mnemonic 

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Reactivity Series Mnemonic

Reaction of metals with cold water

• Potassium, sodium and calcium react with cold water to form a metal hydroxide and hydrogen gas:

metal + water →  metal hydroxide + hydrogen

• Potassium

  • Reacts violently with cold water

potassium + water →  potassium hydroxide + hydrogen

2K (s) + 2H₂O (l) → 2KOH (aq) + H₂ (g)

• Sodium

  • Reacts quickly with cold water

sodium + water →  sodium hydroxide + hydrogen

2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g)

• Calcium

  • Reacts less strongly with cold water

calcium + water →  calcium hydroxide + hydrogen

Ca (s) + 2H₂O (l) → Ca(OH)₂ (aq) + H₂ (g)

Reactions of metals with steam

• Magnesium does not react much with cold water but reacts with steam to form a metal oxide and hydrogen gas:

magnesium + steam → magnesium oxide + hydrogen

Mg (s) + H₂O (g)  →  MgO (s) + H₂ (g)

Reaction with dilute hydrochloric acid

• Metals above hydrogen in the reactivity series react with dilute hydrochloric acid

  • The more reactive the metal then the more vigorous the reaction will be

  • Metals that are placed high on the reactivity series such as potassium and sodium are very dangerous and react explosively with acids

• Metals below hydrogen in the reactivity series do not react with dilute hydrochloric acid

• When hydrochloric acid reacts with a metal it forms a salt and hydrogen gas:

metal + acid ⟶ salt + hydrogen

Metals reacting with dilute hydrochloric acid

• Metals that do react with dilute hydrochloric acid include:

1. Magnesium

magnesium + hydrochloric acid → magnesium chloride + hydrogen

Mg (s) + 2HCl (aq) → MgCl₂ (aq) + H₂ (g)

2. Zinc

zinc + hydrochloric acid → zinc chloride + hydrogen

Zn (s) + 2HCl (aq) → ZnCl₂ (aq) + H₂ (g)

3. Iron

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

Fe (s) + 2HCl (aq) → FeCl₂ (aq) + H₂ (g)

Metals that do not react with dilute hydrochloric acid

• Metals that do not react with dilute hydrochloric acid include:

1. Copper

copper + dilute hydrochloric acid → no reaction

2. Silver

silver + dilute hydrochloric acid → no reaction

3. Gold

gold + dilute hydrochloric acid → no reaction

• The more reactive the metal, the more vigorous the reaction with dilute hydrochloric acid is

Deducing the order of reactivity

• The order of reactivity of metals can be deduced by making experimental observations

  • The more vigorous the reaction, the more reactive the metal

• If two metals both react with water, the more vigorous reaction shows the more reactive metal

• If metals do not react with water, their order can be deduced from their reactions with dilute hydrochloric acid

• Temperature change can also be used

  • The greater the temperature change in a reaction involving a metal, the more reactive the metal is