Class 10 - Carbon and Its Compounds: Important Notes for Boards 2025
1. Introduction to Carbon
• Atomic Number: 6
• Valency: 4 (forms four covalent bonds).
• Unique Properties:
▪ Catenation: Ability to form long chains of carbon atoms.
▪ Tetravalency: Forms stable covalent bonds with other atoms (H, O, N, etc.).
▪ Allotropes: Different forms of carbon (e.g., diamond, graphite, fullerenes).
2. Covalent Bonding
• Carbon compounds are formed by sharing electrons (covalent bonds).
• Example: Methane (CH₄):
▪ Carbon shares one electron with each of the four hydrogen atoms.
3. Hydrocarbons
• Compounds of carbon and hydrogen.
• Types:
▪ Saturated Hydrocarbons (Alkanes): Single bonds only (e.g., methane,
ethane).
• General formula: CₙH₂ₙ₊₂
▪ Unsaturated Hydrocarbons:
• Alkenes: One or more double bonds (e.g., ethene). General formula:
CₙH₂ₙ
• Alkynes: One or more triple bonds (e.g., ethyne). General formula:
CₙH₂ₙ₋₂
4. Functional Groups
• Definition: Atoms or groups of atoms that define the chemical properties of organic
compounds.
Functional Group Formula Example Suffix
Alcohol -OH CH₃OH (Methanol) -ol
Aldehyde -CHO CH₃CHO (Ethanal) -al
Ketone >C=O CH₃COCH₃ (Propanone) -one
Carboxylic Acid -COOH CH₃COOH (Ethanoic Acid) -oic acid
Halogen (Haloalkanes) -X (F, Cl, Br) CH₃Cl (Chloromethane) Prefix: Halo-
5. Homologous Series
• A series of organic compounds having the same functional group and similar
chemical properties.
• Characteristics:
▪ Same general formula.
▪ Differ by a CH₂ unit.
▪ Gradation in physical properties (e.g., boiling points).
Example: Alkane Series
• Methane (CH₄), Ethane (C₂H₆), Propane (C₃H₈), Butane (C₄H₁₀).
6. Important Reactions of Carbon Compounds
1. Combustion:
i. Carbon compounds burn in oxygen to produce CO₂, H₂O, and energy.
ii. Example: CH₄ + 2O₂ → CO₂ + 2H₂O + Heat
2. Oxidation:
i. Alcohols oxidize to acids.
ii. Example: CH₃CH₂OH → CH₃COOH
3. Addition Reaction (Unsaturated hydrocarbons):
i. Example: C₂H₄ + H₂ → C₂H₆ (in presence of Ni catalyst).
4. Substitution Reaction (Saturated hydrocarbons):
i. Example: CH₄ + Cl₂ → CH₃Cl + HCl (in presence of sunlight).
7. Ethanol (C₂H₅OH)
• Physical Properties:
▪ Colorless liquid, pleasant smell.
▪ Soluble in water.
• Chemical Properties:
▪ Combustion: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O.
▪ Reaction with Sodium:
• 2C₂H₅OH + 2Na → 2C₂H₅ONa + H₂↑
• Uses:
▪ Used in alcoholic beverages.
▪ Used as a solvent and fuel.
8. Ethanoic Acid (Acetic Acid, CH₃COOH)
• Physical Properties:
▪ Sour taste.
▪ Freezing point: 16.6°C (glacial acetic acid).
• Chemical Properties:
▪ Reaction with Bases:
• CH₃COOH + NaOH → CH₃COONa + H₂O.
▪ Reaction with Carbonates:
• 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂↑
• Uses:
▪ Used in vinegar (5-8% solution).
▪ Used in food preservation.
9. Soap and Detergents
• Soap: Sodium or potassium salts of fatty acids (e.g., stearic acid).
▪ Example: C₁₇H₃₅COONa.
• Detergents: Synthetic cleaning agents, effective in hard water.
Cleaning Action of Soap:
• Soap molecules have:
▪ Hydrophilic Head: Attracted to water.
▪ Hydrophobic Tail: Attracted to oil/grease.
• Form micelles around grease and wash it away.
10. Important Definitions
1. Catenation: Self-linking property of carbon atoms.
2. Isomerism: Compounds with the same molecular formula but different structures.
i. Example: Butane (C₄H₁₀): n-Butane and Iso-Butane.
11. Practice Questions
1. What is a homologous series? Give an example.
2. Write the balanced chemical equation for the combustion of ethanol.
3. Explain the cleaning action of soap.
4. Differentiate between saturated and unsaturated hydrocarbons.
12. Diagrams to Practice
1. Covalent bonding in methane (CH₄).
2. Structure of ethanoic acid (CH₃COOH).
3. Formation of micelles by soap molecules.
These notes cover all key concepts and ensure a solid foundation for your board exams!
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