What is the Reactivity Series of Metals?
The Reactivity Series of Metals is a list of metals arranged in decreasing order of their reactivity (ability to lose electrons and form positive ions).
Metals placed at the top of the series are more reactive, while metals at the bottom are less reactive.
Reactivity Series of Metals
| Order | Metal | Symbol |
|---|---|---|
| 1 | Potassium | K |
| 2 | Sodium | Na |
| 3 | Calcium | Ca |
| 4 | Magnesium | Mg |
| 5 | Aluminium | Al |
| 6 | Zinc | Zn |
| 7 | Iron | Fe |
| 8 | Lead | Pb |
| 9 | Hydrogen* | H |
| 10 | Copper | Cu |
| 11 | Mercury | Hg |
| 12 | Silver | Ag |
| 13 | Gold | Au |
Note: Hydrogen is not a metal but is included in the series for comparison.
Why is the Reactivity Series Important?
The reactivity series helps us predict:
- Which metal is more reactive.
- Which metal can displace another metal.
- How metals react with water.
- How metals react with acids.
- Methods used for extraction of metals.
- Corrosion tendency of metals.
Characteristics of Metals in the Reactivity Series
Highly Reactive Metals
Examples:
- Potassium (K)
- Sodium (Na)
- Calcium (Ca)
Properties:
- React vigorously with water.
- React quickly with oxygen.
- Stored under kerosene oil.
- Never found free in nature.
Moderately Reactive Metals
Examples:
- Magnesium (Mg)
- Aluminium (Al)
- Zinc (Zn)
- Iron (Fe)
Properties:
- React with acids.
- React slowly with water.
- Commonly used in industries.
Least Reactive Metals
Examples:
- Copper (Cu)
- Silver (Ag)
- Gold (Au)
Properties:
- Do not react easily.
- Found in free state in nature.
- Resistant to corrosion.
Metals and Their Reaction with Water
| Metal | Reaction with Water |
|---|---|
| Potassium | Very violent reaction |
| Sodium | Very vigorous reaction |
| Calcium | Reacts readily |
| Magnesium | Reacts with hot water |
| Aluminium | Reacts slowly |
| Zinc | Reacts with steam |
| Iron | Reacts with steam |
| Copper | No reaction |
| Silver | No reaction |
| Gold | No reaction |
Example
Potassium reacts violently with water:
[
2K + 2H_2O \rightarrow 2KOH + H_2 + Heat
]
Metals and Their Reaction with Acids
Metals above hydrogen react with dilute acids and produce hydrogen gas.
General Reaction
Metal + Acid \rightarrow Salt + H_2
Example
[
Zn + H_2SO_4 \rightarrow ZnSO_4 + H_2
]
Observation
- Zinc, Iron, Magnesium react with acids.
- Copper, Silver and Gold do not react with dilute acids.
Displacement Reactions and Reactivity Series
A more reactive metal can displace a less reactive metal from its salt solution.
Example
[
Zn + CuSO_4 \rightarrow ZnSO_4 + Cu
]
Here:
- Zinc is more reactive than Copper.
- Zinc displaces Copper from copper sulphate solution.
Important Rule
More Reactive Metal → Displaces Less Reactive Metal
Less Reactive Metal → Cannot Displace More Reactive Metal
Reactivity Series and Extraction of Metals
The position of a metal in the reactivity series determines how it is extracted.
| Metal Type | Examples | Extraction Method |
|---|---|---|
| Highly Reactive | K, Na, Ca | Electrolysis |
| Moderately Reactive | Zn, Fe, Pb | Reduction with carbon |
| Less Reactive | Cu, Ag, Au | Found free or simple extraction |
Key NCERT Point
- Highly reactive metals cannot be reduced using carbon.
- They are extracted by electrolysis.
- Less reactive metals may occur in native state.
Reactivity Series Mnemonic
Easy Trick
“Please Stop Calling Me A Zebra Instead Try Learning How Copper Saves Gold”
| Word | Metal |
|---|---|
| Please | Potassium |
| Stop | Sodium |
| Calling | Calcium |
| Me | Magnesium |
| A | Aluminium |
| Zebra | Zinc |
| Instead | Iron |
| Try | Lead |
| Learning | Hydrogen |
| How | Copper |
| Copper | Mercury |
| Saves | Silver |
| Gold | Gold |
Applications of Reactivity Series
- Predicting chemical reactions.
- Understanding corrosion.
- Metal extraction processes.
- Industrial chemistry.
- Laboratory displacement reactions.
- Selection of metals for construction and manufacturing.
Quick Revision Table
| Property | Highly Reactive Metals | Less Reactive Metals |
|---|---|---|
| Position | Top | Bottom |
| Water Reaction | Fast | No reaction |
| Acid Reaction | Vigorous | Very little or none |
| Corrosion | High | Low |
| Extraction | Electrolysis | Simple methods |
| Examples | K, Na, Ca | Cu, Ag, Au |
Practice Questions
Short Answer Questions
1. What is the reactivity series?
Answer: The reactivity series is the arrangement of metals in decreasing order of their reactivity.
2. Which metal is the most reactive?
Answer: Potassium (K).
3. Which metal is the least reactive?
Answer: Gold (Au).
4. Why is hydrogen included in the reactivity series?
Answer: Hydrogen is included for comparing the reactivity of metals with acids.
5. What is a displacement reaction?
Answer: A reaction in which a more reactive metal displaces a less reactive metal from its salt solution.
Fill in the Blanks
- Metals are arranged in the reactivity series in ______ order of reactivity.
Answer: decreasing - Potassium is more reactive than ______.
Answer: Sodium - Metals above hydrogen can displace ______ from acids.
Answer: hydrogen - Zinc can displace ______ from copper sulphate solution.
Answer: copper - Gold is one of the ______ reactive metals.
Answer: least
MCQs (Multiple Choice Questions)
1. Which is the most reactive metal?
A) Copper
B) Iron
C) Potassium
D) Gold
Answer: C) Potassium
2. Which metal is placed just above hydrogen?
A) Zinc
B) Lead
C) Iron
D) Copper
Answer: B) Lead
3. Which metal can displace copper from CuSO₄ solution?
A) Gold
B) Silver
C) Zinc
D) Copper
Answer: C) Zinc
4. Which metal is used as a standard for comparison in acid reactions?
A) Oxygen
B) Carbon
C) Nitrogen
D) Hydrogen
Answer: D) Hydrogen
5. Which metal reacts most vigorously with water?
A) Iron
B) Copper
C) Potassium
D) Silver
Answer: C) Potassium
6. Which of the following is a least reactive metal?
A) Calcium
B) Zinc
C) Silver
D) Magnesium
Answer: C) Silver
7. Highly reactive metals are generally extracted by:
A) Filtration
B) Distillation
C) Electrolysis
D) Crystallization
Answer: C) Electrolysis
8. Which metal reacts with steam but not cold water?
A) Gold
B) Iron
C) Silver
D) Copper
Answer: B) Iron
9. Which metal is located below hydrogen?
A) Zinc
B) Magnesium
C) Copper
D) Aluminium
Answer: C) Copper
10. The reactivity series is useful for predicting:
A) Color of metals
B) Density only
C) Chemical reactivity of metals
D) Atomic size only
Answer: C) Chemical reactivity of metals
Key Takeaway
The Reactivity Series of Metals is a fundamental NCERT concept that arranges metals from most reactive (Potassium) to least reactive (Gold). It helps predict reactions with water and acids, understand displacement reactions, and determine suitable methods for metal extraction.
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