Reactions of Metals (AQA GCSE Chemistry)
Metals undergo a variety of chemical reactions depending on their position in the reactivity series. More reactive metals react vigorously with oxygen, water and acids, while less reactive metals react more slowly or not at all. Understanding these reactions is essential for AQA GCSE Chemistry examinations.
What Determines Metal Reactivity?
A metal reacts by losing electrons and forming positive ions. Metals that lose electrons easily are more reactive.
Metal Reactivity Series
| Most Reactive | Least Reactive |
|---|---|
|
Potassium Sodium Lithium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead |
Hydrogen Copper Silver Gold Platinum |
Reactions of Metals with Oxygen
Most metals react with oxygen to produce metal oxides.
Example: Magnesium
Magnesium burns with a bright white flame and forms a white powder of magnesium oxide.
Example: Iron
Iron reacts more slowly with oxygen and eventually rusts in the presence of water.
Reactions of Metals with Water
The reaction depends on the metal's position in the reactivity series.
| Metal | Reaction with Cold Water |
|---|---|
| Potassium | Very violent reaction |
| Sodium | Very rapid reaction |
| Calcium | Steady reaction |
| Magnesium | Very slow reaction |
| Zinc, Iron, Copper | No reaction |
Example: Sodium and Water
Sodium floats on water, moves rapidly across the surface and releases hydrogen gas.
Reactions with Steam
Some metals that do not react significantly with cold water react with steam.
Magnesium and Steam
Iron and Steam
Reactions of Metals with Acids
Reactive metals react with dilute acids to produce a salt and hydrogen gas.
Magnesium and Hydrochloric Acid
Zinc and Sulfuric Acid
Displacement Reactions
A more reactive metal can displace a less reactive metal from its compound.
Example
Zinc is more reactive than copper, so zinc displaces copper from copper sulfate solution.
Observations in Metal Reactions
| Observation | Possible Cause |
|---|---|
| Bubbles | Hydrogen gas produced |
| Temperature increase | Exothermic reaction |
| Colour change | Displacement reaction |
| Bright flame | Rapid oxidation |
Required Practical Connection
Students may investigate how different metals react with acids by measuring:
- Hydrogen production
- Temperature change
- Rate of reaction
- Relative reactivity of metals
AQA Exam Tips
- More reactive metals lose electrons more easily.
- Metal + Oxygen → Metal Oxide.
- Metal + Water → Metal Hydroxide + Hydrogen.
- Metal + Acid → Salt + Hydrogen.
- A more reactive metal displaces a less reactive metal.
- Hydrogen is below lead and above copper in the reactivity series.
Exam Question
Why does magnesium react more vigorously with hydrochloric acid than copper?
Answer: Magnesium is more reactive than copper and loses electrons more readily, so it reacts rapidly with the acid to produce hydrogen gas.
Exam Question
Predict whether iron will displace copper from copper sulfate solution.
Answer: Yes. Iron is more reactive than copper and displaces it from solution.
Quick Revision Summary
- More reactive metals lose electrons more easily.
- Reactive metals react vigorously with water and acids.
- More reactive metals displace less reactive metals.
- Metals below carbon can be extracted using carbon reduction.
- Metals above carbon require electrolysis.
- Rusting requires both oxygen and water.
- Galvanising protects iron from corrosion.
Summary
The reactions of metals depend upon their reactivity. Reactive metals readily react with oxygen, water and acids, while less reactive metals show limited reactions. The reactivity series allows chemists to predict reaction outcomes, displacement reactions and methods of metal extraction.