Reactivity series (AQA GCSE Chemistry): Revision Notes
Reactivity series
What is the reactivity series?
The reactivity series is a fundamental concept in chemistry that shows metals arranged in order of how easily they react.
When metals react, they lose electrons to become positive ions. The easier it is for a metal to form positive ions, the more reactive that metal is.
Scientists work out this order by testing how metals react with water and dilute acids. This experimental approach allows us to compare the relative reactivity of different metals under controlled conditions.
The reactivity series order
Here are the metals in order from most reactive to least reactive:
Most reactive:
- Potassium - fizzes violently with water and acid
- Sodium - fizzes quickly with water and acid
- Lithium - fizzes steadily with water and acid
- Calcium - fizzes with water, bubbles quickly with acid
- Magnesium - fizzes very slowly with water, bubbles quickly with acid
Less reactive:
- Carbon - no reaction with water or acid
- Zinc - no reaction with water, fizzes with acid
- Iron - no reaction with water, fizzes very slowly with acid
- Hydrogen - included for comparison
- Copper - no reaction with water or acid
Least reactive
The metals at the top are much more dangerous to handle than those at the bottom due to their violent reactions with water and acids.
How metals react with water and acids
Reactive metals follow two main patterns when they undergo chemical reactions:
With water:
- Metal + water → metal hydroxide + hydrogen gas
- Example:
With dilute acids:
- Metal + acid → metal salt + hydrogen gas
- Example:
The hydrogen gas produced makes the fizzing or bubbling you see during these reactions. This gas can be collected and tested - it makes a squeaky pop when lit with a burning splint.
Displacement reactions
A more reactive metal can push out (displace) a less reactive metal from its compound. This is one of the most important applications of the reactivity series.
The rule: More reactive metals displace less reactive metals.
Worked Example: Displacement Reactions
Example 1: Zinc displaces copper
Example 2: Magnesium displaces hydrogen
Example 3: Carbon displaces zinc
This happens because the more reactive metal forms positive ions more easily. The less reactive metal is forced out of its compound and appears as the pure metal.
Key Points to Remember:
- Metals are arranged by reactivity - how easily they form positive ions
- Most reactive metals are at the top - potassium, sodium, lithium
- Least reactive metals are at the bottom - copper is very unreactive
- More reactive metals displace less reactive ones from compounds
- All metal reactions with acids produce hydrogen gas - this causes the fizzing