More reactive metals displace less reactive metals from their compounds in aqueous solutions.
For example, when Fe is placed in a solution of CuSO4 it replaces Cu from the solution.
Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
On the other hand if you place a silver wire in a solution of CuSO4, no reaction occurs because silver is less reactive than copper.
Ag (s) + CuSO4 (aq) → No reaction
However, when a copper wire is dipped in AgNO3 solution, silver is replaced and deposited on copper wire.
Cu (s) + 2 AgNO3 (aq) → 2Ag (s) + Cu(NO3)2 (aq)
This indicates that copper is more reactive than silver. In general, a more reactive metal displaces a less reactive metal from its salt solution.
If we take solution of different metals and place other metals in these solutions, we can compare the reactivity of metals with respect to each other. The arrangement of metals in the decreasing order of their activity is known as activity or reactivity series. It is also known as electrochemical series.
Most reactive metal to Least reactive metal: