CBSE Class 10 Science Chapter 4 Carbon & Its Compounds Notes

Carbon and Its Compounds is Chapter 4 of NCERT Class 10 Science and an important Chemistry chapter for CBSE board exam preparation. This chapter explains why carbon forms a large number of compounds, how covalent bonds are formed, how carbon compounds are named, and how compounds like ethanol, ethanoic acid, soaps, and detergents are used in daily life.

These Carbon and Its Compounds Class 10 Notes are written in simple language to help students revise the chapter quickly. The notes cover complete CBSE Class 10 Science Chapter 4 topics, covalent bonding, electron dot structures, tetravalency, catenation, saturated and unsaturated hydrocarbons, homologous series, functional groups, IUPAC nomenclature, chemical properties of carbon compounds, ethanol, ethanoic acid, esterification, saponification, soaps, detergents, and micelle formation.

Students can use these CBSE Class 10 Science notes for school exams, pre-board exams, CBSE board revision, MCQs, assertion-reason questions, previous year questions, case-based questions, and long-answer questions.

Class 10 Science Chapter 4 Carbon & Its Compounds Notes: Overview

Carbon and Its Compounds Class 10 Notes PDF Download

Students can download the Carbon and Its Compounds Class 10 Notes PDF for offline revision. The PDF is useful for quick revision before tests and board exams because it includes definitions, formulas, chemical reactions, diagrams, tables, and exam-focused questions.

Why is Carbon Important?

Carbon is an important element because it forms a very large number of compounds. Most substances found in living organisms, fuels, medicines, plastics, soaps, detergents, food materials, and natural products contain carbon.

Carbon forms many compounds mainly because of two properties:

1. Tetravalency
2. Catenation

Due to these properties, carbon can form straight chains, branched chains, ring structures, single bonds, double bonds, triple bonds, and compounds with different functional groups.

Covalent Bond in Carbon Compounds

Carbon has atomic number 6. Its electronic configuration is 2, 4. This means carbon has four electrons in its outermost shell.

To become stable, carbon needs four more electrons. However, carbon does not easily lose or gain four electrons. Instead, carbon shares electrons with other atoms and forms covalent bonds.

Why Does Carbon Form Covalent Bonds?

Carbon forms covalent bonds because:

• Carbon has four valence electrons.
• Losing four electrons to form C⁴⁺ requires a large amount of energy.
• Gaining four electrons to form C⁴⁻ is difficult because the nucleus cannot strongly hold ten electrons.
• Carbon completes its octet by sharing electrons with other atoms.

Properties of Covalent Compounds

Electron Dot Structure Class 10

Electron dot structures show valence electrons as dots around the symbols of atoms. They help students understand how atoms share electrons in covalent compounds.

Electron Dot Structure of Methane

Methane has one carbon atom and four hydrogen atoms. Carbon shares one electron with each hydrogen atom and forms four single covalent bonds.

Formula: CH₄

Structure:

Electron Dot Structure of Ethane

Ethane has two carbon atoms and six hydrogen atoms.

Formula: C₂H₆

Simple structural formula:

CH₃—CH₃

Electron Dot Structure of Ethene

Ethene has a double bond between two carbon atoms.

Formula: C₂H₄

Simple structural formula:

CH₂=CH₂

Electron Dot Structure of Ethyne

Ethyne has a triple bond between two carbon atoms.

Formula: C₂H₂

Structure:

H — C ≡ C — H

Simple structural formula:

HC≡CH

Tetravalency of Carbon

Tetravalency means the ability of carbon to form four covalent bonds. Since carbon has four valence electrons, it shares these electrons with atoms such as hydrogen, oxygen, nitrogen, chlorine, and carbon.

Example

In methane, carbon forms four covalent bonds with four hydrogen atoms.

CH₄

This tetravalent nature helps carbon form a wide variety of compounds.

Catenation in Carbon

Catenation is the ability of carbon atoms to form bonds with other carbon atoms. Due to catenation, carbon can form long chains, branched chains, and ring structures.

Examples of Carbon Chains

Why Does Carbon Show Catenation?

Carbon shows strong catenation because the carbon-carbon bond is strong and stable. This allows carbon atoms to form large and complex molecules.

Allotropes of Carbon

Allotropes are different physical forms of the same element. Carbon exists in different allotropic forms because carbon atoms can arrange themselves in different ways.

Common Allotropes of Carbon

Diamond vs Graphite

Hydrocarbons Class 10

Hydrocarbons are compounds made up of only carbon and hydrogen.

Examples of Hydrocarbons

Hydrocarbons are of two main types:

1. Saturated hydrocarbons
2. Unsaturated hydrocarbons

Saturated Hydrocarbons

Saturated hydrocarbons contain only single bonds between carbon atoms. They are also called alkanes.

General Formula of Alkanes

CₙH₂ₙ₊₂

Examples of Alkanes

Saturated hydrocarbons are generally less reactive than unsaturated hydrocarbons.

Unsaturated Hydrocarbons

Unsaturated hydrocarbons contain at least one double or triple bond between carbon atoms.

They are of two types:

1. Alkenes
2. Alkynes

Alkenes

Alkenes contain at least one carbon-carbon double bond.

General formula:

CₙH₂ₙ

Example:

Ethene = C₂H₄

Structural formula:

CH₂=CH₂

Alkynes

Alkynes contain at least one carbon-carbon triple bond.

General formula:

CₙH₂ₙ₋₂

Example:

Ethyne = C₂H₂

Structural formula:

HC≡CH

Difference Between Saturated and Unsaturated Hydrocarbons

Alkanes, Alkenes and Alkynes

Homologous Series

A homologous series is a family of organic compounds that have the same functional group and similar chemical properties. Two consecutive members of a homologous series differ by a —CH₂ group.

Characteristics of Homologous Series

• Members have the same functional group.
• Members have the same general formula.
• Consecutive members differ by —CH₂.
• Consecutive members differ in molecular mass by 14 u.
• Chemical properties are similar.
• Physical properties change gradually with molecular mass.

Example: Alkane Homologous Series

Isomerism in Carbon Compounds

Isomers are compounds that have the same molecular formula but different structural arrangements.

Isomers of Butane

Molecular formula:

C₄H₁₀

Butane has two structural isomers.

1. n-Butane

CH₃—CH₂—CH₂—CH₃

2. Isobutane

CH₃ | CH₃ — CH — CH₃

Isomers of Pentane

Pentane, C₅H₁₂, has three structural isomers:

1. n-Pentane
2. Isopentane
3. Neopentane

Functional Groups Class 10

A functional group is an atom or group of atoms that gives specific chemical properties to a carbon compound.

Important Functional Groups

IUPAC Nomenclature Class 10

IUPAC nomenclature is the systematic method of naming carbon compounds. Students often find this topic difficult, so it should be revised step by step.

Simple Rules for Naming Carbon Compounds

1. Identify the longest carbon chain.
2. Count the number of carbon atoms.
3. Select the correct word root.
4. Check whether the compound has single, double, or triple bonds.
5. Identify the functional group.
6. Add the correct suffix or prefix.
7. Number the carbon chain when required.

Word Roots Based on Carbon Atoms

Suffix Based on Bond Type

Examples of IUPAC Names

Chemical Properties of Carbon Compounds

The main chemical properties of carbon compounds in Class 10 are:

1. Combustion
2. Oxidation
3. Addition reaction
4. Substitution reaction

These reactions are very important for CBSE board exams because they are often asked in short-answer, long-answer, reasoning, and application-based questions.

Important Reactions in Carbon and Its Compounds Class 10

Students should revise these important reactions from Carbon and Its Compounds Class 10 Notes because they are frequently asked in board exams, MCQs, reasoning questions, and application-based questions.

Combustion Reactions of Carbon Compounds

Carbon compounds burn in oxygen to form carbon dioxide, water, heat, and light. This reaction is known as combustion.

Combustion of Methane

Equation:

CH₄ + 2O₂ → CO₂ + 2H₂O + heat + light

Explanation:
Methane burns in oxygen to form carbon dioxide and water. A large amount of heat and light is released during this reaction.

Combustion of Ethanol

Equation:

C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat

Explanation:
Ethanol burns in oxygen to form carbon dioxide and water with the release of heat.

Remember:
Saturated hydrocarbons usually burn with a clean blue flame, while unsaturated hydrocarbons may burn with a yellow smoky flame due to incomplete combustion.

Oxidation of Ethanol

Ethanol can be oxidised to ethanoic acid in the presence of strong oxidising agents such as alkaline potassium permanganate or acidified potassium dichromate.

Equation:

CH₃CH₂OH + 2[O] → CH₃COOH + H₂O

Word equation:

Ethanol + Oxygen → Ethanoic acid + Water

Oxidising agents used:

• Alkaline KMnO₄
• Acidified K₂Cr₂O₇

Exam Tip:
In this reaction, ethanol changes into ethanoic acid. This is why oxidising agents are important in converting alcohols into carboxylic acids.

Addition Reaction

Unsaturated hydrocarbons contain double or triple bonds. They undergo addition reactions because atoms can be added across these multiple bonds.

Hydrogenation of Ethene

Equation:

CH₂=CH₂ + H₂ → CH₃—CH₃

Word equation:

Ethene + Hydrogen → Ethane

Condition:
Nickel is used as a catalyst.

Use:
Hydrogenation is used to convert vegetable oils into solid or semi-solid fats.

Substitution Reaction

Saturated hydrocarbons generally undergo substitution reactions. In this reaction, one atom or group of atoms is replaced by another atom or group.

Chlorination of Methane

Equation:

CH₄ + Cl₂ → CH₃Cl + HCl

Word equation:

Methane + Chlorine → Chloromethane + Hydrogen chloride

Condition:
Sunlight is required.

Common Mistake:
Do not call this an addition reaction. Methane is a saturated hydrocarbon, so it undergoes substitution reaction.

Addition Reaction vs Substitution Reaction

Ethanol Class 10

Ethanol is an alcohol with the molecular formula C₂H₅OH. It is a colourless liquid and mixes with water.

Properties of Ethanol

• Colourless liquid
• Pleasant smell
• Soluble in water
• Burns with a clean flame
• Reacts with sodium metal
• Can be oxidised to ethanoic acid

Uses of Ethanol

• Used as a solvent
• Used in medicines and laboratory preparations
• Used in perfumes
• Used as a fuel
• Used in sanitising solutions

Reactions of Ethanol

Reaction of Ethanol with Sodium

Equation:

2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂

Word equation:

Ethanol + Sodium → Sodium ethoxide + Hydrogen

Observation:
Bubbles of hydrogen gas are produced.

Oxidation of Ethanol

Equation:

CH₃CH₂OH + 2[O] → CH₃COOH + H₂O

Word equation:

Ethanol + Oxygen → Ethanoic acid + Water

Condition:
Alkaline KMnO₄ or acidified K₂Cr₂O₇ is used as the oxidising agent.

Ethanoic Acid Class 10

Ethanoic acid is a carboxylic acid with the formula CH₃COOH. It is commonly known as acetic acid. A dilute solution of acetic acid in water is called vinegar.

Properties of Ethanoic Acid

• Sour taste
• Soluble in water
• Turns blue litmus red
• Reacts with bases
• Reacts with carbonates and hydrogen carbonates
• Forms esters with alcohols

Why is Pure Ethanoic Acid Called Glacial Acetic Acid?

Pure ethanoic acid freezes at a temperature close to room temperature and forms ice-like crystals. Therefore, it is called glacial acetic acid.

Reactions of Ethanoic Acid

Reaction with Sodium Hydroxide

Equation:

CH₃COOH + NaOH → CH₃COONa + H₂O

Word equation:

Ethanoic acid + Sodium hydroxide → Sodium ethanoate + Water

Reaction type:
Neutralisation reaction

Reaction with Sodium Carbonate

Equation:

2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂

Word equation:

Ethanoic acid + Sodium carbonate → Sodium ethanoate + Water + Carbon dioxide

Observation:
Brisk effervescence is seen due to the evolution of CO₂ gas.

Reaction with Sodium Hydrogen Carbonate

Equation:

CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

Word equation:

Ethanoic acid + Sodium hydrogen carbonate → Sodium ethanoate + Water + Carbon dioxide

Observation:
Brisk effervescence is produced because carbon dioxide gas is released.

Esterification Reaction

Esterification is the reaction between a carboxylic acid and an alcohol to form an ester and water.

Reaction Between Ethanoic Acid and Ethanol

Equation:

CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Word equation:

Ethanoic acid + Ethanol → Ethyl ethanoate + Water

Condition:
Concentrated H₂SO₄ is used.

Observation:
A sweet, fruity smell is produced due to the formation of ester.

Remember:
Esters are commonly recognised by their pleasant fruity smell.

Saponification Reaction

Saponification is the reaction in which an ester reacts with a base to form alcohol and the sodium or potassium salt of a carboxylic acid.

Saponification of Ethyl Ethanoate

Equation:

CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH

Word equation:

Ethyl ethanoate + Sodium hydroxide → Sodium ethanoate + Ethanol

General equation:

Ester + Base → Salt of carboxylic acid + Alcohol

Important:
In soap preparation, long-chain esters react with sodium hydroxide or potassium hydroxide to form soap and alcohol.

Esterification vs Saponification

Soaps and Detergents Class 10

Soaps and detergents are cleansing agents. They help remove dirt, oil, and grease from clothes and skin.

What is Soap?

Soap is the sodium or potassium salt of a long-chain carboxylic acid.

What is Detergent?

Detergents are synthetic cleansing agents, usually made from ammonium or sulphonate salts of long-chain hydrocarbons.

Structure of Soap Molecule

A soap molecule has two parts:

1. Hydrophilic head
   This part is attracted to water.
2. Hydrophobic tail
   This part is attracted to oil and grease.

Simple Soap Molecule Diagram

Water-loving head Oil-loving tail O -------------------------------

Cleansing Action of Soap

The cleansing action of soap is based on the formation of micelles.

When soap is added to dirty water, the hydrophobic tail of soap dissolves in oil or grease, while the hydrophilic head remains in water. Many soap molecules arrange themselves around the oil droplet and form a spherical structure called a micelle.

The oil droplet is trapped inside the micelle and gets washed away with water.

Micelle Formation Diagram

O O O O O O O O Oil / Dirt O O O O O O O O O = Water-loving head outside Tails point inward towards oil/dirt

Why Do Soaps Not Work Well in Hard Water?

Hard water contains calcium and magnesium ions. These ions react with soap to form an insoluble substance called scum. Due to scum formation, soap does not produce enough lather and its cleansing action becomes weak.

Simple Reaction

Soap + Ca²⁺ / Mg²⁺ ions → Scum

Detergents work better than soaps in hard water because they do not form scum easily.

Soap vs Detergent

Proper Structural Formula Format

Use these formula formats throughout the page so the content looks clean and student-friendly.

Operator-style Equation Formatting Rule

For this page, write formulas directly in proper chemical format:

Carbon and Its Compounds Important Questions

One-mark Questions

1. What is catenation?
2. What is tetravalency?
3. Define covalent bond.
4. What is a homologous series?
5. Name the functional group present in ethanol.
6. What is the formula of ethanoic acid?
7. What is a micelle?
8. Why does carbon form covalent bonds?

Two-mark Questions

1. Write two properties of covalent compounds.
2. Differentiate between saturated and unsaturated hydrocarbons.
3. What is the difference between ethanol and ethanoic acid?
4. Why do soaps not work well in hard water?
5. Write the electron dot structure of methane.
6. Explain hydrogenation with one example.

Three-mark Questions

1. Explain the versatile nature of carbon.
2. Write the rules for naming simple carbon compounds.
3. Explain esterification with a chemical equation.
4. Explain saponification with a chemical equation.
5. Describe the cleansing action of soap.
6. Differentiate between addition and substitution reactions.

Five-mark Questions

1. Explain covalent bonding in carbon compounds with electron dot structures of methane, ethene, and ethyne.
2. Describe the chemical properties of carbon compounds with suitable examples.
3. Explain ethanol and ethanoic acid with important properties and reactions.
4. What are soaps and detergents? Explain the cleansing action of soap with a labelled diagram.
5. Explain homologous series, functional groups, and nomenclature with examples.

Case-based Question on Carbon and Its Compounds

A student takes a small amount of ethanol in a test tube and adds a piece of sodium metal to it. Bubbles of gas are observed. In another experiment, the student heats ethanol with alkaline potassium permanganate and observes that ethanol changes into another compound with acidic properties.

Questions

1. Which gas is evolved when ethanol reacts with sodium?
2. Write the chemical equation for the reaction of ethanol with sodium.
3. Which compound is formed when ethanol is oxidised?
4. Name the functional group present in the oxidised product.
5. Which oxidising agent is used in the second experiment?

Answers

1. Hydrogen gas is evolved.
2. 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂
3. Ethanoic acid is formed.
4. Carboxylic acid group, —COOH.
5. Alkaline potassium permanganate is used.

Assertion and Reason Questions

Question 1

Assertion: Carbon forms a large number of compounds.
Reason: Carbon shows tetravalency and catenation.

Answer: Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Question 2

Assertion: Ethene undergoes addition reaction.
Reason: Ethene is an unsaturated hydrocarbon with a carbon-carbon double bond.

Answer: Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Question 3

Assertion: Soaps are not effective in hard water.
Reason: Calcium and magnesium ions in hard water react with soap to form scum.

Answer: Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

Common Mistakes Students Should Avoid

Carbon and Its Compounds becomes easier when students understand the logic behind structures and reactions instead of memorising everything. Focus on electron dot structures, functional groups, IUPAC names, balanced reactions, ethanol, ethanoic acid, esterification, saponification, and soap micelles. Practise diagrams and reactions repeatedly because they are often asked in board exams.