Properties of Non-Metals (NCERT Notes)

Introduction

Non-metals are elements that generally do not exhibit the physical and chemical properties of metals. They play an important role in nature and daily life. Examples of non-metals include oxygen, nitrogen, carbon, sulfur, phosphorus, chlorine, and iodine.

According to NCERT, non-metals are generally poor conductors of heat and electricity and do not possess metallic characteristics.

What are Non-Metals?

Non-metals are elements that gain electrons during chemical reactions.
They are found in solid, liquid, and gaseous states.
Most non-metals are essential for living organisms.
They form acidic or neutral oxides.

Examples of Non-Metals

Non-Metal	Symbol	Common Use
Oxygen	O	Respiration
Nitrogen	N	Fertilizers
Carbon	C	Fuels, graphite
Sulfur	S	Sulfuric acid
Phosphorus	P	Matchsticks
Chlorine	Cl	Water purification
Iodine	I	Medicines

Physical Properties of Non-Metals

1. Poor Conductors of Heat and Electricity

Most non-metals do not conduct heat and electricity.
Exception: Graphite (a form of carbon) conducts electricity.

2. Non-Lustrous

Non-metals generally do not have a shiny surface.
They appear dull.

3. Not Malleable

They cannot be beaten into thin sheets.

4. Not Ductile

They cannot be drawn into wires.

5. Brittle Nature

Solid non-metals break easily when hammered.

6. Low Density

Most non-metals have lower density than metals.

7. Low Melting and Boiling Points

Many non-metals melt and boil at relatively low temperatures.

8. Different Physical States

Non-metals exist in all three states:
- Solid: Sulfur, Carbon
- Liquid: Bromine
- Gas: Oxygen, Nitrogen

Chemical Properties of Non-Metals

1. Reaction with Oxygen

Non-metals react with oxygen to form oxides.
Most non-metal oxides are acidic.

Example:

Carbon + Oxygen → Carbon Dioxide

CO₂ is an acidic oxide.

2. Reaction with Water

Most non-metals do not react with water.

3. Reaction with Acids

Non-metals generally do not react with dilute acids.

4. Gain Electrons

Non-metals tend to gain electrons.
They form negatively charged ions (anions).

5. Form Covalent Compounds

Non-metals usually share electrons to form covalent bonds.

Example:

Water (H₂O)
Carbon dioxide (CO₂)

Comparison Between Metals and Non-Metals

Property	Metals	Non-Metals
Lustre	Shiny	Dull
Conductivity	Good conductor	Poor conductor
Malleability	Malleable	Non-malleable
Ductility	Ductile	Non-ductile
Sonority	Sonorous	Non-sonorous
Electron Tendency	Lose electrons	Gain electrons
Oxides	Basic	Acidic

Importance of Non-Metals

Oxygen

Essential for respiration.

Nitrogen

Used in fertilizers.
Helps plant growth.

Carbon

Present in all living organisms.
Used as fuel.

Chlorine

Used in water purification.

Sulfur

Used in manufacturing sulfuric acid.

Phosphorus

Used in fertilizers and matchsticks.

Exceptions Among Non-Metals

Non-Metal	Exception
Graphite	Conducts electricity
Diamond	Hardest natural substance
Bromine	Only liquid non-metal at room temperature
Iodine	Lustrous non-metal

Key Points to Remember

Non-metals are generally poor conductors of heat and electricity.
They are neither malleable nor ductile.
Most non-metals are brittle in solid form.
Non-metals gain electrons during chemical reactions.
Their oxides are usually acidic.
Oxygen, nitrogen, carbon, sulfur, and chlorine are important non-metals.
Graphite conducts electricity despite being a non-metal.
Bromine is the only liquid non-metal at room temperature.

Practice Questions

Short Answer Questions

1. What are non-metals?

Answer: Non-metals are elements that generally do not show metallic properties and tend to gain electrons during chemical reactions.

2. Why is graphite an exception among non-metals?

Answer: Graphite conducts electricity, whereas most non-metals do not.

3. Name the only liquid non-metal.

Answer: Bromine.

4. Give two examples of gaseous non-metals.

Answer: Oxygen and Nitrogen.

5. What type of oxides do non-metals generally form?

Answer: Acidic oxides.

Fill in the Blanks

Non-metals are generally ______ conductors of electricity.
Answer: poor
Bromine is a ______ non-metal.
Answer: liquid
Graphite is a form of ______.
Answer: carbon
Non-metals usually ______ electrons.
Answer: gain
Oxygen is necessary for ______.
Answer: respiration

Multiple Choice Questions (MCQs)

1. Which of the following is a non-metal?

A. Iron
B. Copper
C. Sulfur
D. Aluminium

Answer: C. Sulfur

2. Which non-metal conducts electricity?

A. Sulfur
B. Oxygen
C. Graphite
D. Nitrogen

Answer: C. Graphite

3. Which is the only liquid non-metal?

A. Mercury
B. Bromine
C. Chlorine
D. Sulfur

Answer: B. Bromine

4. Non-metals are generally:

A. Malleable
B. Ductile
C. Sonorous
D. Brittle

Answer: D. Brittle

5. Oxygen is used for:

A. Respiration
B. Jewellery
C. Wiring
D. Construction

Answer: A. Respiration

6. Non-metals usually form:

A. Basic oxides
B. Acidic oxides
C. Neutral alloys
D. Metallic oxides

Answer: B. Acidic oxides

7. Which non-metal is used in water purification?

A. Carbon
B. Sulfur
C. Chlorine
D. Nitrogen

Answer: C. Chlorine

8. Non-metals tend to:

A. Lose electrons
B. Gain electrons
C. Share protons
D. Lose neutrons

Answer: B. Gain electrons

9. Which non-metal is hardest in nature?

A. Sulfur
B. Diamond
C. Bromine
D. Iodine

Answer: B. Diamond

10. Which property is NOT shown by non-metals?

A. Brittleness
B. Poor conductivity
C. Malleability
D. Dull appearance

Answer: C. Malleability

Conclusion

Non-metals are an important group of elements that differ significantly from metals in their physical and chemical properties. They are generally dull, brittle, poor conductors of heat and electricity, and tend to gain electrons during reactions. Understanding the properties of non-metals helps explain their uses in respiration, fertilizers, water purification, fuels, and various industrial processes. These concepts form an essential part of NCERT Science studies.Introduction

Non-metals are elements that generally do not exhibit the physical and chemical properties of metals. They play an important role in nature and daily life. Examples of non-metals include oxygen, nitrogen, carbon, sulfur, phosphorus, chlorine, and iodine.

According to NCERT, non-metals are generally poor conductors of heat and electricity and do not possess metallic characteristics.

What are Non-Metals?

Non-metals are elements that gain electrons during chemical reactions.
They are found in solid, liquid, and gaseous states.
Most non-metals are essential for living organisms.
They form acidic or neutral oxides.

Examples of Non-Metals

Non-Metal	Symbol	Common Use
Oxygen	O	Respiration
Nitrogen	N	Fertilizers
Carbon	C	Fuels, graphite
Sulfur	S	Sulfuric acid
Phosphorus	P	Matchsticks
Chlorine	Cl	Water purification
Iodine	I	Medicines

AI Image Prompt 1

File Name: properties-of-non-metals-overview.png

Alt Text: Various non-metals including oxygen, sulfur, carbon, phosphorus, and chlorine

Description: Educational NCERT-style infographic showing common non-metals with symbols, physical forms, and everyday uses on a clean white background.

AI Image Prompt:
“NCERT style educational infographic showing common non-metals such as oxygen, nitrogen, carbon, sulfur, phosphorus, chlorine and iodine with labels, symbols, and daily life uses, clean textbook illustration, white background, colorful educational design, high resolution”

Physical Properties of Non-Metals

1. Poor Conductors of Heat and Electricity

Most non-metals do not conduct heat and electricity.
Exception: Graphite (a form of carbon) conducts electricity.

2. Non-Lustrous

Non-metals generally do not have a shiny surface.
They appear dull.

3. Not Malleable

They cannot be beaten into thin sheets.

4. Not Ductile

They cannot be drawn into wires.

5. Brittle Nature

Solid non-metals break easily when hammered.

6. Low Density

Most non-metals have lower density than metals.

7. Low Melting and Boiling Points

Many non-metals melt and boil at relatively low temperatures.

8. Different Physical States

Non-metals exist in all three states:
- Solid: Sulfur, Carbon
- Liquid: Bromine
- Gas: Oxygen, Nitrogen

AI Image Prompt 2

File Name: physical-properties-of-non-metals.png

Alt Text: Physical properties of non-metals showing brittleness and lack of lustre

Description: Science diagram comparing physical properties of non-metals such as brittleness, dull appearance, and poor conductivity.

AI Image Prompt:
“Educational science chart showing physical properties of non-metals including brittle nature, dull appearance, poor conductivity, non-malleability, and non-ductility, NCERT textbook style, labeled illustrations, classroom learning poster”

Chemical Properties of Non-Metals

1. Reaction with Oxygen

Non-metals react with oxygen to form oxides.
Most non-metal oxides are acidic.

Example:

Carbon + Oxygen → Carbon Dioxide

CO₂ is an acidic oxide.

2. Reaction with Water

Most non-metals do not react with water.

3. Reaction with Acids

Non-metals generally do not react with dilute acids.

4. Gain Electrons

Non-metals tend to gain electrons.
They form negatively charged ions (anions).

5. Form Covalent Compounds

Non-metals usually share electrons to form covalent bonds.

Example:

Water (H₂O)
Carbon dioxide (CO₂)

Comparison Between Metals and Non-Metals

Property	Metals	Non-Metals
Lustre	Shiny	Dull
Conductivity	Good conductor	Poor conductor
Malleability	Malleable	Non-malleable
Ductility	Ductile	Non-ductile
Sonority	Sonorous	Non-sonorous
Electron Tendency	Lose electrons	Gain electrons
Oxides	Basic	Acidic

Importance of Non-Metals

Oxygen

Essential for respiration.

Nitrogen

Used in fertilizers.
Helps plant growth.

Carbon

Present in all living organisms.
Used as fuel.

Chlorine

Used in water purification.

Sulfur

Used in manufacturing sulfuric acid.

Phosphorus

Used in fertilizers and matchsticks.

AI Image Prompt 3

File Name: uses-of-non-metals.png

Alt Text: Uses of oxygen, nitrogen, chlorine, carbon and sulfur

Description: Educational poster showing important uses of major non-metals in daily life and industries.

AI Image Prompt:
“Colorful educational infographic showing uses of oxygen for respiration, nitrogen in fertilizers, chlorine in water purification, carbon in fuels, sulfur in industries, NCERT science diagram, labeled and easy to understand”

Exceptions Among Non-Metals

Non-Metal	Exception
Graphite	Conducts electricity
Diamond	Hardest natural substance
Bromine	Only liquid non-metal at room temperature
Iodine	Lustrous non-metal

AI Image Prompt 4

File Name: exceptions-of-non-metals.png

Alt Text: Graphite, diamond, bromine and iodine showing exceptions among non-metals

Description: NCERT-style science illustration highlighting important exceptions in the properties of non-metals.

AI Image Prompt:
“Educational science diagram showing graphite conducting electricity, diamond hardness, liquid bromine, and lustrous iodine as exceptions among non-metals, labeled NCERT textbook illustration”

Key Points to Remember

Non-metals are generally poor conductors of heat and electricity.
They are neither malleable nor ductile.
Most non-metals are brittle in solid form.
Non-metals gain electrons during chemical reactions.
Their oxides are usually acidic.
Oxygen, nitrogen, carbon, sulfur, and chlorine are important non-metals.
Graphite conducts electricity despite being a non-metal.
Bromine is the only liquid non-metal at room temperature.