Class 10 Science - Chapter 4: Carbon and Its Compounds

Quick Revision Notes & Important Formulas (MP Board)

1. Introduction & Bonding in Carbon

Atomic Number of Carbon (C) = 6
Electronic Configuration = 2, 4 (Tetravalent)
Covalent Bond (सहसंयोजी बंध): A chemical bond formed by the sharing of electron pairs between two atoms to achieve a stable octet configuration.
Carbon cannot gain 4 electrons ($C^{4-}$) or lose 4 electrons ($C^{4+}$) due to energy considerations. Hence, it forms covalent bonds.

2. Versatile Nature of Carbon (कार्बन की सर्वतोमुखी प्रकृति)

Catenation (श्रृंखलन): The unique property of carbon to form bonds with other carbon atoms, giving rise to long straight chains, branched chains, or ring structures.
Tetravalency (चतुःसंयोजकता): Carbon has a valency of 4; it can bond with four other mono-valent atoms (like Hydrogen) or atoms of other elements (Oxygen, Nitrogen, Sulphur, Chlorine).

3. Allotropes of Carbon (कार्बन के अपररूप)

Elements existing in different physical forms having similar chemical properties:

Diamond (हीरा): Each carbon atom is bonded to 4 other carbon atoms in a rigid 3D structure. Hardest natural substance; non-conductor of electricity.
Graphite (ग्रेफाइट): Each carbon atom is bonded to 3 other carbon atoms in hexagonal layers held by weak Van der Waals forces. Soft, slippery, and a good conductor of electricity (due to free electrons).
Buckminsterfullerene ($C_{60}$): Carbon atoms arranged in the shape of a football.

4. Classification of Hydrocarbons (हाइड्रोकार्बन)

Hydrocarbons are compounds containing only Carbon and Hydrogen.

Parameter	Saturated Hydrocarbons (संतृप्त)	Unsaturated Hydrocarbons (असंतृप्त)
Bonds	Carbon-Carbon Single Bond (C–C)	Carbon-Carbon Double (C=C) or Triple (C≡C) Bond
Family	Alkanes	Alkenes & Alkynes
Flame	Clean blue flame	Yellow smoky flame
Reactivity	Less reactive	Highly reactive

5. Chemical Formulas of Hydrocarbons

Hydrocarbon Series	General Formula	Functional Group / Bond	Example (n = 2)
Alkane (ऐल्केन)	`C_n H_{2n+2}`	Single Bond (`-C-C-`)	Ethane (`C_2 H_6`)
Alkene (ऐल्कीन)	`C_n H_{2n}`	Double Bond (`>C=C<`)	Ethene (`C_2 H_4`)
Alkyne (ऐल्काइन)	`C_n H_{2n-2}`	Triple Bond (`-C≡C-`)	Ethyne (`C_2 H_2`)

Note: n = number of carbon atoms.

IUPAC Naming Prefixes based on Number of Carbon Atoms:

1 Carbon = Meth-
2 Carbons = Eth-
3 Carbons = Prop-
4 Carbons = But-
5 Carbons = Pent-
6 Carbons = Hex-

6. Homologous Series (समजातीय श्रेणी)

A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain.

Key Characteristics:

Adjacent members differ by a -CH2- group.
Molecular mass differs by 14 u.
Similar chemical properties, but physical properties (melting point, boiling point) show a gradual gradation.

7. Functional Groups (प्रकार्यात्मक समूह)

Functional Group	Formula	Prefix / Suffix	Example
Halo (Chloro/Bromo)	`-Cl`, `-Br`	Prefix: `Chloro-` / `Bromo-`	Chloroethane (`C_2 H_5 Cl`)
Alcohol (ऐल्कोहॉल)	`-OH`	Suffix: `-ol`	Ethanol (`C_2 H_5 OH`)
Aldehyde (ऐल्डिहाइड)	`-CHO`	Suffix: `-al`	Ethanal (`CH_3 CHO`)
Ketone (कीटोन)	`>C=O`	Suffix: `-one`	Propanone (`CH_3 COCH_3`)
Carboxylic Acid (कार्बोक्सिलिक अम्ल)	`-COOH`	Suffix: `-oic acid`	Ethanoic acid (`CH_3 COOH`)

8. Chemical Properties of Carbon Compounds

A. Combustion Reaction (दहन)

Carbon compounds burn in oxygen to produce $CO_2$, water, heat, and light.

C + O2 → CO2 + Heat + Light
CH4 + 2 O2 → CO2 + 2 H2O + Heat + Light

B. Oxidation Reaction (ऑक्सीकरण)

Alcohols are oxidized to carboxylic acids using oxidizing agents like alkaline $KMnO_4$ or acidified $K_2Cr_2O_7$.

CH3-CH2OH + 2[O] --(Alkaline KMnO4 + Heat)--> CH3COOH + H2O

C. Addition Reaction (योगात्मक अभिक्रिया)

Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as Nickel (Ni) or Palladium (Pd) to give saturated hydrocarbons (Hydrogenation of vegetable oils).

R2C = CR2 + H2 --(Ni / Pd Catalyst)--> R2CH - CHR2

D. Substitution Reaction (प्रतिस्थापन अभिक्रिया)

In the presence of sunlight, chlorine is added to saturated hydrocarbons fast.

CH4 + Cl2 --(Sunlight)--> CH3Cl + HCl

9. Important Carbon Compounds

A. Ethanol ($C_2H_5OH$)

Physical state: Liquid at room temperature, soluble in water in all proportions.
Reaction with Sodium: 2 C2H5OH + 2 Na → 2 C2H5ONa (Sodium Ethoxide) + H2 ↑
Dehydration Reaction: Heating ethanol at $443 \text{ K}$ with excess concentrated $H_2SO_4$ gives ethene. C2H5OH --(Conc. H2SO4 at 443 K)--> CH2=CH2 + H2O

B. Ethanoic Acid ($CH_3COOH$ / Acetic Acid)

5–8% solution of acetic acid in water is called Vinegar (सिरका).
Pure ethanoic acid has a melting point of $290 \text{ K}$ ($17^\circ\text{C}$), so it often freezes in winter, giving it the name Glacial Acetic Acid.

Important Reactions of Ethanoic Acid:

Esterification Reaction (एस्टरीकरण): Reaction with alcohol in the presence of acid catalyst produces sweet-smelling Esters. CH3COOH + C2H5OH --(Acid)--> CH3COOC2H5 (Ethyl Ethanoate) + H2O
Saponification (साबुनीकरण): Conversion of ester back into alcohol and sodium salt of carboxylic acid using an alkali ($NaOH$). Used to prepare soap. CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
Reaction with Base: CH3COOH + NaOH → CH3COONa + H2O
Reaction with Carbonates & Hydrogen Carbonates: 2 CH3COOH + Na2CO3 → 2 CH3COONa + H2O + CO2 ↑ CH3COOH + NaHCO3 → CH3COONa + H2O + CO2 ↑

10. Soaps and Detergents (साबुन और डिटर्जेंट)

Structure of a Soap Molecule:

Ionic End (Head): Hydrophilic (Water-loving / जलरागी) - Soluble in water.
Hydrocarbon End (Tail): Hydrophobic (Water-hating / जलविरागी) - Soluble in oil/dirt.

Micelle Formation (मिसेल निर्माण):

When soap is on the surface of water, the hydrophobic tails align along dirt/oil particles, while the hydrophilic heads stay in water, forming a spherical cluster called a Micelle.
Micelles help in pulling dirt out from clothes into the water.

Difference Between Soap and Detergent:

Property	Soap (साबुन)	Synthetic Detergent (डिटर्जेंट)
Chemical Composition	Sodium or Potassium salts of long-chain fatty acids.	Ammonium or Sulphonate salts of long-chain fatty acids.
Action in Hard Water	Forms insoluble precipitate called Scum (ineffective).	Does not form scum; works effectively in both hard and soft water.
Biodegradability	Biodegradable (Eco-friendly).	Mostly non-biodegradable (Causes water pollution).

Key Formulas & Symbols Summary

Methane: CH4
Ethane: C2H6
Ethene: C2H4
Ethyne: C2H2
Ethanol: C2H5OH
Ethanoic Acid: CH3COOH
Ester: R-COO-R'
General Alkane Formula: C_n H_{2n+2}
General Alkene Formula: C_n H_{2n}
General Alkyne Formula: C_n H_{2n-2}

Carbon and its Compounds

📐 Formula & Cheat Sheet (English)