NEET Physics: Waves – NCERT Masterclass & 100 MCQ Quiz

ORGANIC CHEMISTRY: BASIC PRINCIPLES & TECHNIQUES

NCERT Masterclass & NEET Study Module (GOC)

1. Tetravalence of Carbon & Hybridisation

Carbon has a unique property called Catenation (ability to form long chains/rings). It is tetravalent (forms 4 bonds).

• $sp^3$ hybridisation: Single bonds only (e.g., Alkanes). Geometry: Tetrahedral ($109.5^\circ$).
• $sp^2$ hybridisation: One double bond (e.g., Alkenes). Geometry: Trigonal Planar ($120^\circ$).
• $sp$ hybridisation: One triple bond or two double bonds (e.g., Alkynes). Geometry: Linear ($180^\circ$).

Counting $\sigma$ and $\pi$ bonds:
A single bond is $1\sigma$. A double bond is $1\sigma + 1\pi$. A triple bond is $1\sigma + 2\pi$.

2. IUPAC Nomenclature & Functional Groups

The name of an organic compound consists of: Prefix + Word Root + Primary Suffix + Secondary Suffix.

Priority Order of Functional Groups (For NEET):
$-COOH > -SO_3H > -COOR > -COCl > -CONH_2 > -CN > -CHO > > C=O > -OH > -NH_2 > > C=C < > -C \equiv C-$

3. Isomerism in Organic Compounds

Two or more compounds having the same molecular formula but different properties are called isomers.

• Structural Isomerism: Chain, Position, Functional, Metamerism (different alkyl chains on either side of polyvalent functional group like -O-, -S-), Tautomerism (Keto-enol).
• Stereoisomerism: Same structural formula but different relative arrangement of atoms in space (Geometrical and Optical).

4. Fundamental Concepts in Organic Reaction Mechanism

• Nucleophiles: Electron rich species ($OH^-, CN^-, H_2O, NH_3$). They seek positive centers.
• Electrophiles: Electron deficient species ($H^+, NO_2^+, BF_3, AlCl_3$). They seek negative centers.

Stability of Intermediates:
Carbocations & Free Radicals: $3^\circ > 2^\circ > 1^\circ > \text{Methyl}$ (Due to +I effect and Hyperconjugation).
Carbanions: $\text{Methyl} > 1^\circ > 2^\circ > 3^\circ$ (Due to +I effect destabilizing the negative charge).

5. Electron Displacement Effects in Covalent Bonds

• Inductive Effect (I Effect): Permanent polarization of a $\sigma$-bond due to electronegativity difference.
  -I groups (Electron Withdrawing): $-NO_2 > -CN > -COOH > -F > -Cl > -Br > -I$
  +I groups (Electron Donating): Alkyl groups ($-CH_3, -C_2H_5$).
• Electromeric Effect (E Effect): Temporary complete transfer of $\pi$-electrons in the presence of an attacking reagent.
• Resonance (Mesomeric) Effect (R or M Effect): Delocalization of $\pi$-electrons or lone pairs. Extremely stabilizing.
• Hyperconjugation (No-bond resonance): Delocalization of $\sigma$-electrons of a C-H bond adjacent to an empty p-orbital or $\pi$-bond. More $\alpha$-hydrogens = More hyperconjugation = More stability.

6. Methods of Purification and Analysis

Purification: Sublimation (for sublimable substances), Crystallisation, Distillation (Fractional for close boiling points, Steam for steam volatile, Reduced pressure for liquids that decompose at BP), Chromatography (based on differential adsorption/partition).

Qualitative Analysis:

• Carbon & Hydrogen: Heating with $CuO$. C oxidizes to $CO_2$ (turns lime water milky). H oxidizes to $H_2O$ (turns anhydrous $CuSO_4$ blue).
• Lassaigne's Test (N, S, Halogens): Fusion with Sodium metal. Nitrogen forms $NaCN$, gives Prussian Blue color $[Fe_4[Fe(CN)_6]_3]$. Sulphur gives violet color with sodium nitroprusside.

Quantitative Analysis: Dumas & Kjeldahl methods for Nitrogen. Carius method for Halogens & Sulphur.

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🚀 NEET GOC MEGA QUIZ (100 MCQ)

Solve the 5 parts below to master Nomenclature, Electronic Effects, Isomerism, and Analysis.

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