Chapter 9 · ICSE Class 8 Chemistry (Selina Concise)

Carbon & Its Compounds

Learn about carbon's unique bonding ability, allotropes, and simple carbon compounds like hydrocarbons.

⚫ Chapter 9

Carbon forming four bonds, showing its tetravalent nature A carbon atom at the centre with four bonds extending outward to four hydrogen atoms, illustrating that carbon always forms four bonds, as seen in methane C Carbon (CH₄): 4 bonds — tetravalent
9.1

Allotropes of Carbon

Carbon exists in different forms (allotropes) like diamond (hard, transparent) and graphite (soft, conducts electricity), due to different atomic arrangements.

1

Why are diamond and graphite so different, even though both are pure carbon?

Their atoms are arranged differently — diamond has a rigid 3D structure, while graphite has layers that can slide, giving each very different properties

2

Which allotrope of carbon conducts electricity?

Graphite

9.2

Simple Hydrocarbons

Hydrocarbons are compounds made of only carbon and hydrogen atoms, forming the basis of fuels like methane and petrol.

1

What elements make up a hydrocarbon?

Only carbon and hydrogen

2

Name a simple hydrocarbon used as a fuel.

Methane (CH₄)

Practice

Exercises

1. Name two allotropes of carbon.

2. Which allotrope of carbon is very hard and doesn't conduct electricity?

3. What is a hydrocarbon?

4. Name a simple hydrocarbon.

5. Why can carbon form so many different compounds?

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