Think of the reactivity series as a ladder of metals. The higher you are on the ladder, the more eager you are to give up your electrons and form a positive ion. When two metals are in contact with each other in an aqueous solution, the metal higher on the ladder will displace the lower one. 🔬
| Rank | Metal |
|---|---|
| 1 | Magnesium (Mg) |
| 2 | Zinc (Zn) |
| 3 | Iron (Fe) |
| 4 | Copper (Cu) |
| 5 | Silver (Ag) |
A metal higher on the ladder will replace a lower metal in its ion form. Below are some common examples:
\$\text{Mg} + \text{Zn}^{2+} \rightarrow \text{Mg}^{2+} + \text{Zn}\$
\$\text{Mg} + \text{Fe}^{2+} \rightarrow \text{Mg}^{2+} + \text{Fe}\$
\$\text{Mg} + \text{Cu}^{2+} \rightarrow \text{Mg}^{2+} + \text{Cu}\$
\$\text{Mg} + 2\text{Ag}^{+} \rightarrow \text{Mg}^{2+} + 2\text{Ag}\$
\$\text{Zn} + \text{Fe}^{2+} \rightarrow \text{Zn}^{2+} + \text{Fe}\$
\$\text{Zn} + \text{Cu}^{2+} \rightarrow \text{Zn}^{2+} + \text{Cu}\$
\$\text{Zn} + 2\text{Ag}^{+} \rightarrow \text{Zn}^{2+} + 2\text{Ag}\$
\$\text{Fe} + \text{Cu}^{2+} \rightarrow \text{Fe}^{2+} + \text{Cu}\$
\$\text{Fe} + 2\text{Ag}^{+} \rightarrow \text{Fe}^{2+} + 2\text{Ag}\$
\$\text{Cu} + 2\text{Ag}^{+} \rightarrow \text{Cu}^{2+} + 2\text{Ag}\$
| Metal | Can Displace Mg? | Can Displace Zn? | Can Displace Fe? | Can Displace Cu? | Can Displace Ag? |
|---|---|---|---|---|---|
| Mg | ❌ | ?? | ?? | ?? | ?? |
| Zn | ❌ | ❌ | ?? | ?? | ?? |
| Fe | ❌ | ❌ | ❌ | ?? | ?? |
| Cu | ❌ | ❌ | ❌ | ❌ | ?? |
| Ag | ❌ | ❌ | ❌ | ❌ | ❌ |
Remember: The reactivity series is a ladder – the higher the metal, the more likely it is to displace a lower metal from its ion. When answering displacement questions, write the reaction in the form
\$ \text{Metal}\text{higher} + \text{Metal}\text{lower}^{2+} \rightarrow \text{Metal}\text{higher}^{2+} + \text{Metal}\text{lower} \$.
Check the order in the ladder before you write the equation.