Metals are important substances found in nature and are widely used in our daily life. According to the NCERT Science syllabus, metals have several physical and chemical properties that make them useful for making machines, utensils, vehicles, wires, buildings, and many other objects.
Introduction to Metals
Metals are generally hard, shiny, strong, and good conductors of heat and electricity. Examples of common metals are:
- Iron (Fe)
- Copper (Cu)
- Aluminium (Al)
- Gold (Au)
- Silver (Ag)
- Zinc (Zn)
Most metals are found in the Earth’s crust in the form of minerals and ores.
What are The Physical Properties of Metals?
1. Lustrous Nature
Metals have a shiny surface called metallic lustre.
- Example: Gold and silver shine brightly.
- Metals can be polished easily.
Uses
- Jewellery
- Decorative items
- Mirrors
2. Hardness
Most metals are hard substances.
- Iron is very hard.
- Sodium and potassium are soft metals and can be cut with a knife.
Uses
- Construction work
- Machines
- Tools
3. Malleability
Metals can be beaten into thin sheets.
This property is called malleability.
- Gold and silver are highly malleable metals.
- Aluminium foil is made due to this property.
4. Ductility
Metals can be drawn into thin wires.
This property is known as ductility.
- Copper wires are used in electrical wiring.
- Gold can be drawn into very thin wires.
Uses
- Electric wires
- Cable industries
5. Conductivity of Heat and Electricity
Metals are good conductors of heat and electricity.
- Copper and aluminium are used in electric wires.
- Iron is used in cooking utensils.
Exception
Lead and mercury are comparatively poor conductors of heat.
6. Sonorous Nature
Metals produce a ringing sound when struck.
This property is called sonority.
Uses
- School bells
- Musical instruments
7. High Melting and Boiling Points
Most metals have high melting and boiling points.
- Tungsten is used in electric bulb filaments due to its high melting point.
Exception
- Gallium and cesium melt at low temperatures.
What Are The Chemical Properties of Metals?
1. Reaction with Oxygen
Metals react with oxygen to form metal oxides.
Example
2Mg + O2 –> 2MgO
Magnesium burns with a bright white flame and forms magnesium oxide.
2. Reaction with Water
Some metals react with water to form metal hydroxide and hydrogen gas.
Example
2Na + 2H2O ->2NaOH + H2
- Sodium reacts violently with water.
- Iron reacts slowly with steam.
3. Reaction with Acids
Metals react with dilute acids to produce salt and hydrogen gas.
Example
Zn + 2HCl \rightarrow ZnCl_2 + H_2
Observation
- Bubbles of hydrogen gas are produced.
4. Reaction with Bases
Some metals react with bases.
Example
- Zinc reacts with sodium hydroxide.
Important Exceptions in Metals
| Property | Exception |
|---|---|
| Liquid metal | Mercury |
| Soft metals | Sodium, Potassium |
| Low melting metals | Gallium, Cesium |
| Poor conductor | Lead |
| Non-sonorous metal | Mercury |
Uses of Metals in Daily Life
| Metal | Uses |
|---|---|
| Iron | Bridges, machines, tools |
| Copper | Electric wires |
| Aluminium | Utensils, aeroplanes |
| Gold | Jewellery |
| Silver | Decorative items |
| Zinc | Galvanization |
Difference Between Metals and Non-Metals
| Metals | Non-Metals |
|---|---|
| Lustrous | Generally dull |
| Good conductors | Poor conductors |
| Malleable | Brittle |
| Ductile | Non-ductile |
| Sonorous | Non-sonorous |
Practice Questions
Very Short Answer Questions
1. What is malleability?
Answer: The property by which metals can be beaten into thin sheets is called malleability.
2. Name a liquid metal.
Answer: Mercury.
3. Which metal is used in electric wires?
Answer: Copper.
4. Which gas is produced when metals react with acids?
Answer: Hydrogen gas.
5. Which property allows metals to make sound?
Answer: Sonority.
Fill in the Blanks
- Metals are good conductors of ______ and electricity.
Answer: heat - The property of making thin wires is called ______.
Answer: ductility - ______ is a liquid metal.
Answer: Mercury - Metals react with oxygen to form ______.
Answer: metal oxides - Gold and silver are highly ______ metals.
Answer: malleable
Multiple Choice Questions (MCQs)
1. Which metal is liquid at room temperature?
A. Iron
B. Mercury
C. Copper
D. Zinc
Answer: Mercury
2. Which property allows metals to be drawn into wires?
A. Malleability
B. Hardness
C. Ductility
D. Sonority
Answer: Ductility
3. Which metal is commonly used in electrical wiring?
A. Copper
B. Sodium
C. Sulphur
D. Phosphorus
Answer: Copper
4. Metals are generally:
A. Soft
B. Brittle
C. Poor conductors
D. Lustrous
Answer: Lustrous
5. Which gas is released when zinc reacts with hydrochloric acid?
A. Oxygen
B. Nitrogen
C. Hydrogen
D. Carbon dioxide
Answer: Hydrogen
6. Which property makes metals suitable for making utensils?
A. Poor conductivity
B. Heat conductivity
C. Brittleness
D. Transparency
Answer: Heat conductivity
7. Which of the following is a soft metal?
A. Iron
B. Sodium
C. Copper
D. Zinc
Answer: Sodium
8. Metals produce sound due to:
A. Ductility
B. Sonority
C. Hardness
D. Brittleness
Answer: Sonority
9. Which metal is used in bulb filaments?
A. Iron
B. Aluminium
C. Tungsten
D. Copper
Answer: Tungsten
10. Metals react with oxygen to form:
A. Acids
B. Bases
C. Metal oxides
D. Salts
Answer: Metal oxides
Conclusion
Metals are extremely useful materials because of their unique physical and chemical properties. Their strength, conductivity, malleability, ductility, and sonorous nature make them essential in industries, transportation, construction, and household applications. Understanding the properties of metals helps students learn how materials are selected for different purposes in science and everyday life.
