Carbon and Its Compounds – Smart & Complete Quick Revision (Class 10)
Carbon is the backbone of life and organic chemistry. Its ability to form strong covalent bonds, long chains, branches, and rings makes it unique among all elements. This chapter explains why carbon forms millions of compounds and how these compounds behave in daily life and exams.
1. Why Carbon Forms So Many Compounds
Carbon shows catenation (self-linking) and tetravalency. Each carbon atom forms four covalent bonds, leading to stable chains and rings.
Example bond formation: $$ \text{Carbon valency} = 4 \Rightarrow \text{forms single, double, or triple bonds} $$
2. Covalent Compounds – Key Properties
Carbon compounds are mostly covalent because carbon does not easily lose or gain electrons.
- Low melting and boiling points
- Poor conductors of electricity
- Generally insoluble in water
3. Hydrocarbons
(a) Saturated Hydrocarbons – Alkanes
Contain only single bonds. General formula: $$ C_nH_{2n+2} $$
Example: Methane ($CH_4$), Ethane ($C_2H_6$)
(b) Unsaturated Hydrocarbons
Alkenes: One double bond, $C_nH_{2n}$
Alkynes: One triple bond, $C_nH_{2n-2}$
4. Homologous Series
A homologous series is a family of organic compounds with:
- Same functional group
- Similar chemical properties
- Successive members differ by $-CH_2$
Example: $$ CH_4,\ C_2H_6,\ C_3H_8 $$
5. Functional Groups (Very High Weightage)
| Group | Formula | Example |
|---|---|---|
| Alcohol | -OH | Ethanol |
| Carboxylic acid | -COOH | Ethanoic acid |
| Aldehyde | -CHO | Ethanal |
| Ketone | >C=O | Propanone |
6. Important Carbon Compounds
Ethanol ($C_2H_5OH$)
Preparation (Fermentation): $$ C_6H_{12}O_6 \xrightarrow{yeast} 2C_2H_5OH + 2CO_2 $$
- Neutral in nature
- Used as solvent, fuel, antiseptic
Ethanoic Acid ($CH_3COOH$)
Acidic in nature, found in vinegar.
Reaction with sodium carbonate: $$ 2CH_3COOH + Na_2CO_3 \rightarrow 2CH_3COONa + H_2O + CO_2 $$
7. Soaps and Detergents
Soap: Sodium or potassium salts of long-chain fatty acids.
Detergent: Ammonium or sulphonate salts.
Soaps fail in hard water due to scum formation: $$ \text{Soap} + Ca^{2+} \rightarrow \text{Insoluble scum} $$
8. High-Yield Exam Checklist
- General formulas of hydrocarbons
- Identification of functional groups
- Difference: soap vs detergent
- Reaction-based MCQs
- Reasoning on properties of covalent compounds
Why This Chapter Is Exam-Critical
Carbon and its compounds contribute heavily to MCQs, case-study questions, and assertion–reason problems. Mastering concepts + reactions ensures accuracy and speed in the exam.
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