MHT-CET Chemistry · Teaching notes

Basic Principles of Organic Chemistry — MHT-CET Chemistry

Basic Principles of Organic Chemistry is a Class 11 chapter and a light one on the MHT-CET paper — about one question a sitting, one in seven HARD. It is the grammar the organic chapters are written in: IUPAC names and the priority order of functional groups, the heterocycles by their heteroatom, the kinds of isomerism and how to spot a chiral carbon, and the electronic effects that rank carbocations and sort groups into donors and withdrawers. Three pages, ten cards, and every PYQ tagged. Read this before the Halogen Derivatives and Alcohols chapters, which assume all of it.

Every subtopic, worked example, formula and trap in one printable document — answers shown, ready to share.

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Subtopic notes

PYQ weightage by concept

10 concepts · 38 PYQs — where the marks actually sit, so you know what to drill first

IUPAC Nomenclature, Functional Groups and Homologous Series18 PYQs · 47%

Concept	PYQs	Share
Heterocyclic Compounds by Heteroatom	5	13%
Priority Order of Functional Groups	5	13%
Naming From a Structure, and Reading Bond-Line Formulas	5	13%
Homologous Series: One CH₂ at a Time	3	8%

Isomerism and Stereochemistry9 PYQs · 24%

Concept	PYQs	Share
Enantiomers and the Fischer Projection	4	11%
Chiral Carbons and Optical Activity	3	8%
Structural Isomerism: Chain, Position, Functional, Metamerism	2	5%

Electronic Effects, Hybridisation, Intermediates and General Reactions11 PYQs · 29%

Concept	PYQs	Share
Hybridisation of Carbon and Counting From a Formula	5	13%
Inductive and Resonance Effects; Carbocation Stability	3	8%
Grignard Reagent, Dry Ice and the Clemmensen Reduction	3	8%

Formula & revision sheet

8 formulas · 2 reference tables · 10 gotchas across all subtopics — the exam-eve cheat-sheet

IUPAC Nomenclature, Functional Groups and Homologous Series

Formulas (2)

Homologous Series: One CH₂ at a Time · Homologous step $M(\text{C}_{n+1}\text{H}_{2n+4}) - M(\text{C}_n\text{H}_{2n+2}) = 14\ \text{g mol}^{-1}$
Naming From a Structure, and Reading Bond-Line Formulas · Naming order $\text{locants: principal group} \to \text{C=C / C≡C} \to \text{substituents (lowest set)};\quad \text{prefixes alphabetical}$

Reference tables (2)

Heterocyclic Compounds by Heteroatom6 rows

Compound	Ring size	Heteroatom	Aromatic?
Pyrrole	5	N	Yes
Furan	5	O	Yes
Thiophene	5	S	Yes The only sulphur ring in the list.
Pyridine	6	N	Yes
Piperidine	6	N	No — saturated Piperidine has N, not S; it is the reduced form of pyridine.
Pyran	6	O	No Pyran contains NO nitrogen.

Pyr- names carry nitrogen except pyran; fur- is oxygen; thio- is sulphur.

Priority Order of Functional Groups11 rows

Rank	Group	Suffix
1	−COOH	-oic acid
2	−SO₃H	-sulphonic acid Above esters and acid chlorides — the 2025 paper keys it over −COCl.
3	−COOR	-oate
4	−COCl	-oyl chloride
5	−CONH₂	-amide
6	−CN	-nitrile
7	−CHO	-al
8	>C=O	-one Lowest of the carbonyl family.
9	−OH	-ol
10	−NH₂	-amine
11	C=C, C≡C	-ene, -yne Never principal over a heteroatom group.

Acid first, then its derivatives in the order ester, chloride, amide, then nitrile, aldehyde, ketone, alcohol, amine.

Watch out for (4)

Taking the difference as 12 or 2
→ Homologous Series: One CH₂ at a Time
Reading 'pyran' as a nitrogen ring
→ Heterocyclic Compounds by Heteroatom
Putting the acid chloride above the ester
→ Priority Order of Functional Groups
Numbering from the substituent-rich end
→ Naming From a Structure, and Reading Bond-Line Formulas

Isomerism and Stereochemistry

Formulas (3)

Structural Isomerism: Chain, Position, Functional, Metamerism · Kinds of structural isomerism $\text{chain} \;|\; \text{position} \;|\; \text{functional group} \;|\; \text{metamerism (alkyls about the group)}$
Chiral Carbons and Optical Activity · Chirality test $\text{C}abcd \text{ with } a \neq b \neq c \neq d \Rightarrow \text{chiral centre}$
Enantiomers and the Fischer Projection · Fischer convention $\text{vertical bonds away from the viewer;}\quad \text{horizontal bonds towards the viewer}$

Watch out for (3)

Calling ether-versus-alcohol pairs metamers
→ Structural Isomerism: Chain, Position, Functional, Metamerism
Checking only the carbon that carries the halogen
→ Chiral Carbons and Optical Activity
Marking 'same chemical properties' as the false statement
→ Enantiomers and the Fischer Projection

Electronic Effects, Hybridisation, Intermediates and General Reactions

Formulas (3)

Hybridisation of Carbon and Counting From a Formula · Hybridisation from bonding $4\ \sigma \Rightarrow sp^3;\qquad 3\ \sigma + 1\ \pi \Rightarrow sp^2;\qquad 2\ \sigma + 2\ \pi \Rightarrow sp$
Inductive and Resonance Effects; Carbocation Stability · Carbocation order $3^\circ > 2^\circ > 1^\circ > \text{CH}_3^+ \quad (\text{+I and hyperconjugation})$
Grignard Reagent, Dry Ice and the Clemmensen Reduction · Grignard with dry ice $\text{R-MgX} \xrightarrow{\ \text{(i) CO}_2\text{, dry ether; (ii) H}_3\text{O}^+\ } \text{R-COOH}$

Watch out for (3)

Hearing 'isopentane' as an alkene
→ Hybridisation of Carbon and Counting From a Formula
Calling −OH a withdrawer because oxygen is electronegative
→ Inductive and Resonance Effects; Carbocation Stability
Forgetting the extra carbon from CO₂
→ Grignard Reagent, Dry Ice and the Clemmensen Reduction