The Reactivity Series
The reactivity series lists metals from most to least reactive: K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au. More reactive metals form positive ions more easily. Metals above hydrogen react with dilute acids; metals above magnesium react with cold water. A more reactive metal displaces a less reactive one from a solution of its compound, e.g. .
Learning objectives
- Recall the reactivity series.
- Describe reactions of metals with water, steam and acids.
- Predict and explain displacement reactions.
Aluminium is high in the reactivity series, yet aluminium pans don't react with water. Why?
Core idea
Potassium bursts into flame in water; gold lies untouched in rivers for millions of years. Ranking metals by reactivity lets you predict reactions you've never seen.
The more easily a metal forms positive ions, the more reactive it is. A more reactive metal will take the place of a less reactive one in its compounds.
1. The series
Carbon and hydrogen are reference points.
Metal A reacts with steam but not cold water. B reacts with neither, nor with dilute acid. C reacts vigorously with cold water.
- Goal
- Order A, B, C.
- Strategy
- Most vigorous reaction first.
- C reacts with cold water; A only with steam.
- B is below hydrogen (no reaction with acid).
2. Displacement
Copper wire is placed in silver nitrate solution.
- Goal
- Observations and ionic equation.
- Strategy
- Copper is above silver.
- Copper loses electrons; silver ions gain them.
- ions are blue.
Why can't you store copper(II) sulfate solution in an iron container?
Summary
- K Na Ca Mg Al C Zn Fe H Cu Ag Au.
- Reactivity = ease of forming positive ions.
- Higher displaces lower.
- Reactivity series
- Metals listed in order of reactivity.
- Displacement
- A more reactive metal replaces a less reactive one in a compound.
- Native metal
- A metal found uncombined in nature.
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