Class 12 · Chemistry · English medium · Part 2
Class 12 Chemistry Part 2 companion
An original companion to Chemistry, NCERT Class 12 Chemistry (2026–27 edition). Official textbook ↗ ncert.nic.in
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Chapters
- ENHinglish
Chapter 6: Haloalkanes and Haloarenes
Haloalkanes (, X on an carbon) and haloarenes (, X on a ring carbon) are classified and named, then linked to the polar, weakening-down-the-group C–X bond. - ENHinglish
Chapter 7: Alcohols, Phenols and Ethers
Alcohols (, OH on carbon), phenols () and ethers () are classified and named by IUPAC rules. - ENHinglish
Chapter 8: Aldehydes, Ketones and Carboxylic Acids
Aldehydes (RCHO), ketones (RCOR′) and carboxylic acids (RCOOH) are named by common and IUPAC rules. - ENHinglish
Chapter 9: Amines
Amines are ammonia derivatives with a pyramidal sp3 nitrogen carrying a lone pair. - ENHinglish
Chapter 10: Biomolecules
Carbohydrates are polyhydroxy aldehydes or ketones (or their polymers), classified by hydrolysis as mono-, oligo- and polysaccharides and as
Also in Hinglish
- Chapter 6: Haloalkanes aur Haloarenes (Hinglish)
- Chapter 7: Alcohols, Phenols aur Ethers (Hinglish)
- Chapter 8: Aldehydes, Ketones and Carboxylic Acids (Hinglish)
- Chapter 9: Amines (Hinglish)
- Chapter 10: Biomolecules (Hinglish)
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acetalऐसीटैलA compound with two –OR groups on one carbon, made from an aldehyde and two alcohol molecules (from a ketone: a ketal).Ch 8 · Aldehydes, Ketones and Carboxylic AcidsacylationऐसिलनReplacing a hydrogen on nitrogen (or oxygen) by an acyl group, RCO-, using an acid chloride or anhydride.Ch 9 · Aminesalcoholऐल्कोहॉलA compound with an –OH group bonded to an sp³ carbon, R-OH.Ch 7 · Alcohols, Phenols and Ethersaldehydeऐल्डिहाइडA carbonyl compound with at least one hydrogen on the carbonyl carbon, RCHO.Ch 8 · Aldehydes, Ketones and Carboxylic Acidsaldolऐल्डोलA β-hydroxy aldehyde or ketone formed when an enolate adds to a C=O group.Ch 8 · Aldehydes, Ketones and Carboxylic Acidsambident nucleophileA nucleophile with two different atoms able to attack, such as cyanide (C or N) and nitrite (O or N).Ch 6 · Haloalkanes and HaloarenesamineऐमीनA compound made by replacing one, two or three hydrogens of ammonia with alkyl or aryl groups; the nitrogen keeps a lone pair.Ch 9 · Aminesammonolysisअमोनी-अपघटनBreaking a C–X bond with ammonia, which replaces the halogen by an amino group.Ch 9 · AminesanomerऐनोमरOne of two cyclic forms of a sugar that differ only in configuration at the anomeric carbon (C1 of glucose).Ch 10 · BiomoleculesC
Cannizzaro reactionकैनिज़ारो अभिक्रियाDisproportionation of an aldehyde without α-hydrogen in concentrated alkali into an alcohol and a carboxylate.Ch 8 · Aldehydes, Ketones and Carboxylic Acidscarbocationकार्बधनायनA planar ion with a positively charged, sp² carbon that has only six valence electrons.Ch 6 · Haloalkanes and Haloarenescarbohydrateकार्बोहाइड्रेटAn optically active polyhydroxy aldehyde or ketone, or a compound that hydrolyses to such units.Ch 10 · Biomoleculescarbonyl groupकार्बोनिल समूहA carbon atom doubly bonded to an oxygen atom, >C=O.Ch 8 · Aldehydes, Ketones and Carboxylic Acidscarboxylic acidकार्बोक्सिलिक अम्लA compound containing the carboxyl group, –COOH.Ch 8 · Aldehydes, Ketones and Carboxylic Acidscarbylamine reactionFormation of a foul-smelling isocyanide when a primary amine is heated with CHCl3 and ethanolic KOH; a test for 1° amines.Ch 9 · AmineschiralकिरलNot superimposable on its own mirror image, like a left hand; an object that is superimposable is achiral.Ch 6 · Haloalkanes and Haloarenescoupling reactionयुग्मन अभिक्रियाAttack of a diazonium ion on a phenol or arylamine ring, joining the rings by –N=N– to give a coloured azo compound.Ch 9 · Aminescyanohydrinसायनोहाइड्रिनA compound with –OH and –CN on the same carbon, made by adding HCN to C=O.Ch 8 · Aldehydes, Ketones and Carboxylic AcidsD
dehydrationनिर्जलीकरणRemoval of a water molecule, for example from an alcohol to give an alkene or an ether.Ch 7 · Alcohols, Phenols and EthersdenaturationविकृतीकरणLoss of a protein's folded shape and activity through heat, pH change or chemicals; the sequence stays intact.Ch 10 · Biomoleculesdenaturation of alcoholMaking ethanol unfit to drink by adding substances such as copper sulphate and pyridine.Ch 7 · Alcohols, Phenols and Ethersdiazonium saltडाइऐज़ोनियम लवणA salt ArN2+ X- made from a primary aromatic amine; stable only in cold solution.Ch 9 · Aminesdiazotisationडाइऐज़ोटीकरणConversion of a primary aromatic amine into a diazonium salt with NaNO2 and acid at 273–278 K.Ch 9 · AminesE
enantiomerOne of a pair of stereoisomers that are non-superimposable mirror images of each other.Ch 6 · Haloalkanes and Haloarenesenzymeएंज़ाइमA biological catalyst, almost always a globular protein, specific for its substrate and reaction.Ch 10 · Biomoleculesessential amino acidआवश्यक ऐमीनो अम्लAn amino acid the body cannot make in enough amount, so it must come from food.Ch 10 · Biomoleculesesterificationएस्टरीकरणForming an ester from an alcohol or phenol and a carboxylic acid, acid chloride or anhydride.Ch 7 · Alcohols, Phenols and Ethersesterificationएस्टरीकरणFormation of an ester and water from a carboxylic acid and an alcohol, catalysed by acid.Ch 8 · Aldehydes, Ketones and Carboxylic AcidsetherईथरA compound with an oxygen atom bonded to two carbon groups, R-O-R'.Ch 7 · Alcohols, Phenols and EthersF
fermentationकिण्वनBreakdown of sugars by enzymes from microbes such as yeast, without air, giving ethanol and carbon dioxide.Ch 7 · Alcohols, Phenols and EthersG
Gabriel phthalimide synthesisA route to pure primary amines: potassium phthalimide is alkylated by R-X and the product is hydrolysed.Ch 9 · Aminesglycosidic linkageग्लाइकोसाइडी बंधThe C–O–C bridge joining two sugar units, formed with loss of water.Ch 10 · BiomoleculesGrignard reagentAn alkyl- or arylmagnesium halide, RMgX, made from a halide and magnesium in dry ether; its carbon is strongly basic.Ch 6 · Haloalkanes and HaloarenesH
haloalkaneहैलोऐल्केनA compound in which a halogen atom is bonded to an sp³ carbon of an alkyl group, R-X.Ch 6 · Haloalkanes and HaloareneshaloareneहैलोऐरीनA compound in which a halogen atom is bonded directly to an sp² carbon of an aromatic ring, Ar-X.Ch 6 · Haloalkanes and Haloareneshaloform reactionहैलोफॉर्म अभिक्रियाConversion of a methyl ketone by a hypohalite into CHX3 and the salt of an acid with one carbon fewer.Ch 8 · Aldehydes, Ketones and Carboxylic AcidshemiacetalहेमीऐसीटैलA compound with –OH and –OR on the same carbon, from one alcohol molecule adding to an aldehyde.Ch 8 · Aldehydes, Ketones and Carboxylic AcidsHinsberg's reagentBenzenesulphonyl chloride, C6H5SO2Cl, used to distinguish and separate 1°, 2° and 3° amines.Ch 9 · AminesHoffmann bromamide degradationConversion of a primary amide by Br2 and NaOH into a primary amine with one carbon fewer.Ch 9 · Amineshormoneहॉर्मोनA chemical messenger made by an endocrine gland and carried in the blood to target cells.Ch 10 · Biomoleculeshydroboration–oxidationAdding BH3 to an alkene, then H2O2 and NaOH, to give an alcohol with –OH on the less substituted carbon.Ch 7 · Alcohols, Phenols and Ethershydrogen bondहाइड्रोजन आबंधAn attraction between a hydrogen bonded to O, N or F and a lone pair on another such atom.Ch 7 · Alcohols, Phenols and EthersI
invert sugarअपवृत्त शर्कराThe laevorotatory equimolar mixture of glucose and fructose obtained by hydrolysing sucrose.Ch 10 · BiomoleculesK
ketoneकीटोनA carbonyl compound with two carbon groups on the carbonyl carbon, RCOR′.Ch 8 · Aldehydes, Ketones and Carboxylic AcidsKolbe reactionSodium phenoxide with CO2 under pressure, then acid, giving 2-hydroxybenzoic (salicylic) acid.Ch 7 · Alcohols, Phenols and EthersL
leaving groupThe atom or group that departs with the bonding pair during substitution or elimination; for haloalkanes it is the halide ion.Ch 6 · Haloalkanes and HaloarenesLucas testConc. HCl with ZnCl2: a 3° alcohol turns it cloudy at once, a 2° alcohol within minutes, a 1° alcohol not at room temperature.Ch 7 · Alcohols, Phenols and EthersM
monosaccharideमोनोसैकेराइडA carbohydrate that cannot be hydrolysed into a simpler sugar, such as glucose or fructose.Ch 10 · BiomoleculesN
nucleophileनाभिकस्नेहीAn electron-rich species (an anion or a molecule with a lone pair) that attacks an electron-poor carbon and forms a new bond to it.Ch 6 · Haloalkanes and Haloarenesnucleophilic additionनाभिकस्नेही योगज अभिक्रियाAddition across C=O that starts with a nucleophile attacking the δ+ carbon.Ch 8 · Aldehydes, Ketones and Carboxylic Acidsnucleotideन्यूक्लियोटाइडA base, a pentose sugar and a phosphate joined together; the unit of DNA and RNA.Ch 10 · BiomoleculesO
optical activityध्रुवण घूर्णकताThe ability of a substance to turn the plane of plane-polarised light; clockwise is (+), anticlockwise is (−).Ch 6 · Haloalkanes and HaloarenesP
peptide bondपेप्टाइड आबंधThe amide link –CO–NH– joining two amino acids in a peptide or protein.Ch 10 · Biomoleculesphenolफ़ीनॉलA compound with an –OH group bonded directly to a carbon of an aromatic ring, Ar-OH; also the simplest one, C6H5OH.Ch 7 · Alcohols, Phenols and Ethersphenoxide ionThe anion C6H5O- left when phenol loses a proton; its charge is spread over oxygen and three ring carbons.Ch 7 · Alcohols, Phenols and EtherspKapKa−log Ka; the smaller the pKa, the stronger the acid.Ch 8 · Aldehydes, Ketones and Carboxylic AcidspKb- log Kb, a measure of base strength: the smaller the pKb, the stronger the base.Ch 9 · Aminesprimary, secondary and tertiary aminesप्राथमिक, द्वितीयक और तृतीयक ऐमीनAmines with one, two or three carbon groups on nitrogen: RNH2, R2NH and R3N.Ch 9 · AminesQ
quaternary ammonium saltचतुष्क अमोनियम लवणA salt of the ion R4N+, in which nitrogen carries four carbon groups and no lone pair.Ch 9 · AminesR
racemic mixtureरेसिमिक मिश्रणA 50: 50 mixture of two enantiomers; it shows no optical rotation and is written with a (±) prefix.Ch 6 · Haloalkanes and Haloarenesreducing sugarअपचायी शर्कराA sugar that reduces Tollens' reagent and Fehling's solution because it has, or can open to give, a free carbonyl group.Ch 10 · BiomoleculesReimer–Tiemann reactionPhenol with CHCl3 and aqueous NaOH, then acid, giving 2-hydroxybenzaldehyde.Ch 7 · Alcohols, Phenols and EthersS
Sandmeyer reactionReplacement of -N2+ by Cl, Br or CN using the matching copper(I) salt.Ch 9 · AminesSN1 reactionUnimolecular nucleophilic substitution: slow ionisation to a carbocation, then fast capture; rate = k[RX].Ch 6 · Haloalkanes and HaloarenesSN2 reactionBimolecular nucleophilic substitution: one step, rate = k[RX][Nu-], back-side attack and inversion of configuration.Ch 6 · Haloalkanes and HaloarenessolvationविलायकनStabilisation of a dissolved ion by solvent molecules clustering round it; in water mainly through hydrogen bonds.Ch 9 · AminesstereocentreA carbon atom bonded to four different groups; swapping any two of them gives the mirror-image arrangement.Ch 6 · Haloalkanes and Haloarenessymmetrical etherAn ether whose two groups on oxygen are identical; if they differ, the ether is unsymmetrical (mixed).Ch 7 · Alcohols, Phenols and EthersV
vitaminविटामिनAn organic compound needed in small amounts in the diet; its lack causes a deficiency disease.Ch 10 · BiomoleculesW
Williamson synthesisMaking an ether by SN2 reaction of a sodium alkoxide or phenoxide with a primary alkyl halide.Ch 7 · Alcohols, Phenols and EthersZ
zwitterionज़्विटर आयनA dipolar ion with -NH3+ and -COO- groups, neutral overall.Ch 10 · BiomoleculesΑ
α-amino acidऐमीनो अम्लA compound with -NH2 and -COOH on the same carbon; the building unit of proteins.Ch 10 · Biomoleculesα-hydrogenα-हाइड्रोजनA hydrogen on the carbon next to a C=O group; it is acidic because its removal gives a resonance-stabilised enolate.Ch 8 · Aldehydes, Ketones and Carboxylic AcidsΒ
β-eliminationविलोपनLoss of a hydrogen from the β-carbon and the halogen from the α-carbon to form a C=C double bond.Ch 6 · Haloalkanes and Haloarenesncert.ai is an independent learning companion aligned to the NCERT curriculum. It is not affiliated with or endorsed by NCERT.