Physical Properties of Metals and Non-Metals (CBSE Class 10 Science)

Understanding the physical properties of metals and non-metals helps us recognize, use, and differentiate these important materials in daily life. Let’s break down each property, provide fun and easy explanations, examples, activities, and end with engaging scenario-based questions!

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Physical Properties of Metals

1. Hardness
2. Lustre
3. Melleability
4. Ductility
5. Good Conductors of Heat and Electricity
6. Sonorous
7. High Melting and Boiling Points
8. High Density

1. Hardness

Explanation:
Most metals are hard. This means they resist being scratched or cut. They can withstand force or pressure.

Important Points:

• Not all metals are equally hard.
• Some metals (like sodium and potassium) are very soft.

Examples:

• Iron (Fe): Very hard; used in buildings and bridges.
• Copper (Cu): Hard, but softer than iron; used in electrical wiring.
• Sodium (Na), Potassium (K): Exception! Can be cut with a knife.

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2. Lustre

Explanation:
Metals have a shiny appearance. This shine is called metallic lustre.

Important Points:

• Metals are often polished for extra shine.

Examples:

• Gold (Au): Bright yellow shine; used in jewellery.
• Silver (Ag): Silvery-white shine; used in mirrors.
• Aluminium (Al): Silvery shine; used in foil.

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3. Malleability

Explanation:
Metals can be hammered or rolled into thin sheets. This is called malleability.

Important Points:

• This property makes metals useful for making sheets and foils.

Examples:

• Gold & Silver: Can be made into very thin leaves for decoration.
• Aluminium: Used for making kitchen foil.

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4. Ductility

Explanation:
Metals can be drawn into thin wires. This property is called ductility.

Important Points:

• Wires are made from the most ductile metals.

Examples:

• Copper: Used for electric wires.
• Aluminium: Used in transmission cables.
• Gold: Can be stretched into the thinnest wires.

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5. Good Conductors of Heat and Electricity

Explanation:
Metals allow heat and electricity to pass through them easily.

Important Points:

• Not all metals conduct equally well.

Examples:

• Silver: Best conductor of electricity.
• Copper: Common in household wiring.
• Aluminium: Used in power lines.

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6. Sonorous

Explanation:
Metals make a ringing sound when hit. This is called sonority.

Examples:

• Copper and Bronze: Used for bells and instruments.
• Iron: Used in gongs and large bells.

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7. High Melting and Boiling Points

Explanation:
Most metals require high temperatures to melt or boil.

Important Points:

• Some metals like mercury are exceptions.

Examples:

• Iron: Melting point about 1538°C.
• Tungsten: One of the highest melting points (around 3400°C).
• Mercury (Hg): A liquid at room temperature (melting point -39°C).

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8. High Density

Explanation:
Metals are usually heavy for their size. Their atoms are closely packed.

Examples:

• Gold: Feels heavy for its size.
• Lead: Another dense, heavy metal.

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Physical Properties of Non-Metals

1. Hardness
2. Lustre
3. Malleability
4. Ductility
5. Poor Conductors of Heat and Electricity
6. Non-sonorous
7. Low Melting and Boiling Points
8. Low Density
9. Color Variety

1. Hardness

Explanation:
Non-metals are mostly soft and can be broken or scratched easily.

Important Points:

• Some exceptions!

Examples:

• Sulphur (S): Soft and powdery.
• Phosphorus (P): Cuts with a knife.
• Iodine (I): Brittle.
• Exception: Diamond (form of carbon) is the hardest natural substance.

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2. Lustre

Explanation:
Non-metals are usually dull, or lack shine.

Examples:

• Sulphur: Yellow, not shiny.
• Coal: Black and dull.
• Exception: Iodine: Looks shiny and crystalline.

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3. Malleability

Explanation:
Non-metals break into powder or smaller pieces if hammered. They cannot be beaten into sheets.

Examples:

• Sulphur, Phosphorus: Break easily.
• Coal: Crumbles.

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4. Ductility

Explanation:
Non-metals cannot be stretched into wires. They are brittle and snap easily.

Examples:

• No wires possible from sulphur, phosphorus, or coal.

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5. Poor Conductors of Heat and Electricity

Explanation:
Most non-metals do not carry heat or electricity.

Important Points:

• There are exceptions!

Examples:

• Sulphur, Phosphorus: Poor conductors.
• Exception: Graphite (carbon): Good conductor; used in electrodes.

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6. Non-sonorous

Explanation:
Non-metals do not ring when hit.

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7. Low Melting and Boiling Points

Explanation:
Most non-metals turn into gases or melt at low temperatures.

Examples:

• Oxygen, Nitrogen: Gases at room temperature.
• Sulphur: Melting point is just 115°C.
• Exception: Diamond: Very high melting point.

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8. Low Density

Explanation:
Atoms of non-metals are loosely packed. They are light.

Examples:

• Gases like hydrogen, oxygen: Very light.

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9. Color Variety

Explanation:
Non-metals come in many different colors.

Examples:

• Sulphur: Yellow.
• Chlorine: Greenish gas.
• Bromine: Reddish-brown liquid.
• Iodine: Violet solid.

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Fun Activities: Exploring Physical Properties

Activity 1: Testing Malleability and Ductility

Materials Needed:

• Small pieces of copper, iron, sulphur, and coal.
• Hammer.
• Steel wire.

Steps:

1. Place a piece of copper on a hard surface. Hit it gently with a hammer.
2. Place a coal piece and hit gently.
3. Try stretching a copper wire. Then, try the same with a thin piece of sulphur.

Observations:

• Copper: Flattens without breaking (shows malleability); stretches (ductile).
• Coal/Sulphur: Breaks into pieces or powder (not malleable/ductile).

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Activity 2: Testing Conductivity

Materials Needed:

• Electric circuit set-up (simple battery, bulb, wires)
• Samples: copper wire, graphite (pencil lead), sulphur piece

Steps:

1. Complete the circuit using the copper wire as a connection; observe the bulb.
2. Replace copper wire with graphite rod; observe.
3. Replace with sulphur piece; observe.

Observations:

• Bulb glows with copper and graphite (copper = metal, graphite = non-metal exception).
• Bulb does not glow with sulphur (non-metal).

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Scenario-Based Questions

1. Scenario: You need to build a bridge that can support a lot of weight.

   • Question: Why should you choose iron instead of sulphur?
   • Answer: Iron is a hard, strong metal that can withstand heavy loads, while sulphur is a soft, brittle non-metal that would break easily.

2. Scenario: You are asked to make wires for electrical wiring at home.

   • Question: Which material would you select: copper, sulphur, or coal? Why?
   • Answer: Copper, because it is metal, highly ductile (can be made into wires), and is an excellent conductor of electricity.

3. Scenario: You are making a bell for a temple.

   • Question: Would you use bronze or graphite? Support your answer.
   • Answer: Bronze, because it is a metal and sonorous (rings when struck), while graphite (a non-metal) is not sonorous.

4. Scenario: Your science project asks you to collect colorful elements.

   • Question: Will you choose only metals? Why/why not?
   • Answer: No. Many non-metals are colorful (e.g., sulphur is yellow, bromine is reddish-brown, iodine is violet), while most metals are greyish or silver.

5. Scenario: Your friend says “All metals are hard and all non-metals are soft.” Do you agree?

   • Answer: No. Exceptions exist! Sodium and potassium (metals) are soft; diamond (a non-metal) is very hard.

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Final Fun Tip

When you handle a wire, use a spoon, collect air in a balloon, or use foil, remember you’re using either a metal or non-metal. What makes your balloon float and your spoon strong? Now you know!

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Remember: Always mention exceptions and give examples for full marks in exams!

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