The reactivity series
The reactivity series
- The reactivity series ranks metals by how reactive they are (carbon and hydrogen included for comparison):
K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au
- The higher a metal, the more easily it forms positive ions:
- K, Na, Ca react with cold water,
- Mg reacts with steam,
- Mg, Zn, Fe react with dilute acid; Cu, Ag, Au do not.
Practice
Which metal is the most reactive?
Potassium is near the top of the reactivity series; gold and copper are near the bottom.
Practice
Which metal does NOT react with dilute hydrochloric acid?
Copper is below hydrogen, so it does not react with dilute acid; Mg, Zn and Fe do.
Displacement & aluminium
- A more reactive metal displaces a less reactive one from a solution of its ions (e.g. zinc displaces copper from copper(II) sulfate).
- Aluminium seems unreactive because a thin, strong oxide layer protects the metal underneath.
Practice
Aluminium seems less reactive than expected because a strong oxide layer protects it.
The thin, tough aluminium oxide layer stops other substances reaching the metal underneath.
You've got it
Key idea
- reactivity series: K Na Ca Mg Al C Zn Fe H Cu Ag Au (most → least reactive)
- higher metal = forms ions more easily (reacts with water/steam/acid)
- displacement: a more reactive metal pushes out a less reactive one; aluminium is protected by an oxide layer