Class 10 Science - Chapter 4: Carbon and Its Compounds

Quick Revision Notes & Important Formulas (MP Board)

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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.

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

1. 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.
2. 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).

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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.

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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

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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-

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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.

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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)

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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

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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:

1. Esterification Reaction (एस्टरीकरण): Reaction with alcohol in the presence of acid catalyst produces sweet-smelling Esters. CH3COOH + C2H5OH --(Acid)--> CH3COOC2H5 (Ethyl Ethanoate) + H2O
2. 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
3. Reaction with Base: CH3COOH + NaOH → CH3COONa + H2O
4. Reaction with Carbonates & Hydrogen Carbonates: 2 CH3COOH + Na2CO3 → 2 CH3COONa + H2O + CO2 ↑ CH3COOH + NaHCO3 → CH3COONa + H2O + CO2 ↑

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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).

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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}