JEE Main Chemistry Revision - Concepts and Definitions

Read Every Day 10 Points and Think of the other points that are implied by them. 

This process will help you to complete intensive study of all the concepts  of the subject by the time you appear for JEE Main in April 2020.

12 January 2019

Haloalkanes and Haloarenes

JEE Syllabus

UNIT 22: ORGANIC COMPOUNDS CONTAINING HALOGENS

General methods of preparation, properties and reactions; Nature of C-X bond; Mechanisms of substitution reactions. Uses; Environmental effects of chloroform - iodoform.

1. The groups which possess two nucleophilic centres are called ambident nucleophiles.

Explanation: An ambident nucleophile has "teeth" on two sides.

It can attack from two different places and form two different products.

For example, the thiocyanate ion, SCN⁻, is a ambident nucleophile. It is a resonance hybrid.

Both the S  and the N  atoms can act as nucleophiles.

So, the SN2  reaction of an alkyl halide with SCN⁻  often leads to a mixture of an alkyl thiocyanate and an alkyl isothiocyanate.

R-X+SCN⁻→X⁻   + R-SCN          + R-NCS
                alkyl            alkyl
                thiocyanate      isothiocyanate
https://socratic.org/questions/what-is-an-ambident-nucleophile


2. The rate of reaction depends on the concentration of both alkyl halid and base, the reation is known as SN2 reactions.

3. The rate of reaction depends on the concentration of alkyl halides, the reaction is known as SN1 reaction.

4. The order of reactivity of alkyl halides for SN1 reactions

3 degree halide > 2 degree halide > 1 degree halide > CH3X
(tertiary)              (secondary)           (primary)

5. The order of reactivity of alkyl halides for SN2 reactions

3 degree halide < 2 degree halide < 1 degree halide < CH3X

6.  In SN1 and SN2 mechanism, the reactivity of halides follows the order

R-I > R-Br > R-Cl > R-F

7. If all the substituents attached to a carbon are different, that carbon is called asymmetric (or) Chiral carbon or stereocentre.

8. The stereo isomers related to each other as non-super imposable images are called enantiomers.

9. A mixture containing two enantiomers in equal proportions will have zero optical rotation, as the rotation due to one isomer will be exactly cancelled by the rotation due to the other isomer. Such a mixture is known as racemic mixture or racemic modification.

10. The process of conversion of enantiomer into a racemic mixture is known as racemisation.


Key words:  ambident nucleophiles, SN2 reactions, SN1 reaction, The order of reactivity of alkyl halides for SN1 reactions (degree of halides),  The order of reactivity of alkyl halides for SN2 reactions(degree of halides), order of  reactivity of halides (based on halogen), asymmetric (or) Chiral carbon or stereocentre, enantiomers, racemic mixture or racemic modification, racemisation.

13 January 2020

11. SN2 reactions of optically active halides are accompanied by inversion of configuration.

12. SN1 reactions are accompanied by racemisation.

13. Finkelstein reaction - The reaction of alkyl chloride (or) bromide with NaI in dry acetone gives Alkyl iodides.

14. Swarts reaction -The reaction of alkyl chloride (or) bromide with metal flourides like AgF, Hg2F2, CoF2, SbF3 on heating gives alkyl fluorides.

15. Haloalkane reacts with KCN to form alkyl cyandie as main product where haloalkane reacts with AgCN to form alkyl isocyanide as the main product.

16. Sandmeyer's reaction - The reaction of benzene diazonium salt with cuprous chloride (or) bromide and HCl gives chlorobenzene or bromobenzene.

Reactions of Cholorobenzene

17. Cholorobenzene reacts with chlorine in presence of AlCl2 gives 1,4-dichlorobenzene as a major product, and 1,2 -dichlorobenzene as a minor product.

18. Cholorobenzene reacts with nitration mixture and gives 1-chloro-4-nitrobenzene as a major product and 1-chloro-2-nitrobenzene as a minor product.

19. Cholorobenzene reacts with CH3Cl in presence of AlCl3 adn gives 1-chloro-4-methylbenzene as a major product and 1-chloro-2-methyl benzene as a minor product.

20. Cholorobenzene reacts with CH3COCl in presence of AlCl3 and gives 4-chloro-acetophenone as a major product and 2-chloro-acetophenone as a minor product.

14 January 2020

21. Fittig reaction: Cholorobenzene reacts with sodium in presence of dry ether - gives diphenyl.

22. Wurtz-Fittig reaction: Cholorobenzene, alkyl halide and sodium react in presence of dry ether and give alkyl benzene.

23. DDT = P, p1-dichlorodiphenyltrichloroethane

24. Grignard reagent (RMgX): Obtained by the reaction of haloalkanes with magnesium metal in dry ether.

25. Freons (CCl2F2) are chlorofluoro compounds of methane and ethane.

26. In dehydrohalogenation reactions, the preferred product is that alkene which has the greater number of alkyl groups attached to the doubly bonded carbon atoms.

Organic Compounds with Functional Groups OH and CHO

JEE Syllabus

UNIT 23: ORGANIC COMPOUNDS CONTAINING OXYGEN

General methods of preparation, properties, reactions and uses

ALCOHOLS, PHENOLS AND ETHERS

Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.

Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer – Tiemann reaction.

Ethers: Structure.

Aldehyde and Ketones: Nature of carbonyl group;Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as – Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of α – hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.

Carboxylic acids: Acidic strength and factors affecting it.

Alcohols and Phenols

1. Methanol (CH3OH) is referred to as wood spirit.

Alcohol from alkenes

2. Alkenes react with water in the presence of acid as catalyst to form alcohols.

Mechanism of alcohol formation

3. Protonation of alkene to form carbocation by electrophylic attack of H3O+.

4. Nucleophylic attack of water on carbocation.

5. Deprotonation to form an alcohol

Key words:   Fittig reaction, Wurtz-Fittig, DDT,  Grignard reagent , Freons,  preferred product in dehydrohalogenation reactions of halides, wood spirit., Alcohol from alkenes ,


15 January 2020

6. Diborane (BH3)2 reacts with alkenesto give trialkyl boranes as addition product.

7. Trialkyl borane is oxidized to  alcohol by hydrogen peroxide in the presence of acqueous sodium hydroxide.

8. With sodium borohydride (NaBh4) or lithiumaluminium hydride (LiAlH4), aldehydes yield primary alcohols. Ketones give secondary alcohols.

9. Primary (1 degree), secondary (2 degree) and tertiary (3 degree) alcohols are distinguished by Lucas test.

Preparation of Phenol

10. Chlorobenzene is fused with NaOH at 623K and 320 atmospheric pressure.  ... Phenol is obtained by acidification of sodium phenoxide.

11. Benzene is sulphonated with oleum and benzene sulphonic is acid formed. The acid is converted to sodium phenoxide on heating with molten sodium hydroxide. Phenol is obtained by acidification of sodium phenoxide.

High boiling points of alcohols

12. The high boiling points of alcohols are mainly due to the presence of intermolecular hydrogen bonding in them which is not present in ethers and hydrocarbons.

13. Propanol has higher boiling point than that of hydrocarbon n-butane due to intermolecular hydrogen bond.

Solubility of alcohols and phenols

14. Solubility of alcohols and phenols in water is due to their ability to form hydrogen bonds with water molecules.

15. The solubility decreases with increase in size of alkyl/aryl groups. Several lower molecular mass alcohols are misible with water in all proportions.

16 January 2020

Acidic nature of phenol.


16. The reactions of phenol with metals (sodium, alumimium) and sodium hydroxide indicate its acidic nature.

For details read: Acidic nature of phenols

17. The hydroxyl group, in phenol is directly attached to the sp2 hybridized carbon of benezene ring which acts as an electron withdrawing group.

18. The reaction of phenol with acqueous sodium hydroxide indicates that phenols are stronger acids than alcohols and water.

19. Due to the higher electronegativity of sp2 hybridised carbon of phenol to which -OH is attached electron density decreases on oxygen.

20. The presence of electron withdrawing groups such as nitro group, enhances the acidic strength of phenol.

21. The effect is more pronounced when withdrawing group is present at ortho and para positions. It is due to the effective delocalisation of negative charge in phenoxide ion.

Oxidizing alcohols 

22. Strong oxidizing agents such as potassium permanganate are used for getting carboxylic acids from alcohols directly.

23. CrO3 in anhydrous medium is used as the oxidizing agent for the isolation of aldehydes.

24. A better reagent for oxidation of primary alcohols to aldehydes in good yield is pyridium chlorochromate (PCC), a complex of chromium trioxide with pyridine and HCl.

25. The -OH group attached to the benzene ring activates it towards electrophilic sustituion. Also it directs the incoming group to ortho and para positions in the ring as these positions become electron rich due to the resonance effect caused by -OH group.


17 January 2020


26. The ortho and para isomers can be separated by steam distillation.

27. Kolbe's reaction: Phenol is treated with sodium hydroxide and carbon dioxide to from salicylic acid.

28. Reimer - Tiemann reaction:Phenol reacts with chloroform in the presence of sodium hydroxide to form salicylaldehyde.

29. Reduction of phenol with zinc dust forms benzene.

30. Oxidation of phenol with chromic acid produces a conjugated diketone known as benzoquinone.

31. Williamson synthesis:

32. Anisole reacts with the alkylhalide and acyl halide in the presence of anhydrous aluminium chloride as catalyst. The alkyl and acyl groups are introduced at ortho and para positions in the resultant  products.

33. Nitration: Anisole reacts with a mixture of concentrated sulphur amd nitric acid to yield a mixture of ortho and para nitroanisole.


18 January 2020

Aldehydes, Ketones and Carboxylic Acids

1. Friedel-craft acylation: Benzene is treated with acetylchloride in the presence of AlCl3 to form acetophenone.

2. Cannizaro reaction: Aldehydes which do not have α-hydrogen atom react with concentrated sodium hydroxide (NaOH) or potassium hydroxide (KOH) in such a way that one molecule get oxidized to acid and the second molecule gets reduced to alcohol.

Note two molecules of aldehyde participates in the reaction.

This self oxidation-reduction under the influence of a base is known as the Cannizzaro's reaction.

Formaldehyde does not possess α-hydrogen atom and therefore undergoes Cannizzaro's reaction. Acetaldehyde does not give this reaction.

3. Aldol Condensation: Aldehydes and ketones containing α-hydrogen (H-atoms attached to the C-atom adjacent to the carbonyl group)undergo condensation in the presence of dilute alkali.

In the resulting compound both aldehyde group and alcohol group are present.

acetaldehyde and acetone undergo aldol condensation.
Formaldehyde, banzaldehyde do not undergo aldol condensation.

4. Cross aldol condensation: Aldol condensation  carried out between different aldehydes (or) ketones. In this process 4 products are obtained.

5. Acid salts are heated with sodalime loose CO2 to form hydrocarbons.

6. HVZ reaction:

7. Carbonyl compounds participate in nucleophylic addition reactions.

8. Carbonyl compounds are treated with HCN to form Cynohydrins.

9. Aldehydes react with one molecule of alcohol in the presence of dry HCL and form alkoxy alcohols. It is called hemiacetal.

10. Aldehydes react with two  molecules of alcohol and form dialkoxy compounds.  It is called acetal.


19 January 2020

11. Formation of semicarbozone:

12. Formation of oxime:

JEE Syllabus topic: Carboxylic acids: Acidic strength and factors affecting it.

13. Presence of electron withdrawing groups increases acidic nature of Carboxylic Acids.

14. Presence of electron releasing groups decreases acidic nature of Carboxylic Acids

15. Feling's reagent.

16. Fehling test

17. Tollen's reagent

18. Tollen's test

19. In benzoic acid electrophylic substitution takes place at meta position.

20. Acetic acid is treated with PCl3/PCl5 to form Benzamide.

20 January 2020

21. Formation of Benzamide

22. Increasing order of acidic strength of various benzoic acids.

23. Decreasing order of acidic strength of given carboxilic acids

Organic Compounds Containing Nitrogen - Amines

JEE Syllabus

UNIT 24: ORGANIC COMPOUNDS CONTAINING NITROGEN

General methods of preparation, properties, reactions and uses

Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.

Diazonium Salts: Importance in synthetic organic chemistry.


1. What are amines?

2, Preparation of aniline.

3. Ammonolysis

4. Reactity of halides with amines - order

5. Primary amines from nitriles

6. Primary amines from amides

7. Gabriel phthalimid synthesis

21 January 2020

8. Hoffman bromamide degradation reaction.

9. Boiling points of different amines.

10. Order of basic nature of amine (Remember acidic nature of phenols)

11. Amines behave as Lewis bases.

12. Alkylation of amines.

13. Acetylation of amines.

14. Benzoylation of amines

15. Carbylamine reaction

16. Amines - nitrous acid reation

17. Diazotisation


22 January 2020

18. Hinsberg reagent

19. Formation of sulphonamide

20. reaction of tertiary amines

21. Ortho and para directing and ring activating group

22. 2,4,6,  tri bromo aniline formation

23. Nitration reaction of aniline

24. Zwitterion

25. Aniline and Friedal crafts reaction

26. Benzene diazonium chloride.

27. Diazonium salt general formula

23 January 2020

28.Sandmeyer reaction

29. Gatterman reaction

Cyanides

1. Formation of cyanides - Aldoximes are dehydrated by acetic anhydride.

2. Hydrolysis of isocyanides

3. Cyanides reaction with Grignard reagent.

4. Cyanides reaction with LiAlH4

5. Ioscyanides reduction with H2/Ni

6. Oxidation of isocynaides


24 January 2020

Inorganic Chemistry

General Principles of Metallurgy

1. Mineral

2. Ore

3. Flux

4. Gangue

5. Slag

6. Matte

7.  Concentration of Ore

8. Froth flotation process


10. Roasting: Process of heating in presence of air.


25 January 2020

11. Calcination

12. Electrometallury

13. Blast furnace - Chemical reactions

14. Extraction of coppoer from copper pyrites

15. Electrolytic refining of copper

16. Ore of aluminium

17. Electrolytic reduction of pure alumina.

18. General methods of refining

19. Role of cryolite

20. Fractional crystallization

26 January 2020

21. Vapour phase refining

22. Composition of alloys. - Brass

23. Uses of metal zinc

24. Uses of metal copper

25. Uses of metal iron

26. Uses of metal aluminium

27. Uses of cast iron

28. Uses of wrought iron

29. Uses of nickel steel

30. Uses of stainless

27 January 2020

P-Block Elements




Updated 20 January 2020,  17 January 2020,

Carboxylic acids: Acidic strength and factors affecting it

A. Reactions due to hydrogen atom of carboxyl group

1. Acidic character

a. Action with blue litmus
all carboxylic acids turn blue litmus red.


b. Reaction with metals: liberation of hydrogen
Carboxylic acids react with active metals such as Na, K, Ca, Mg, Zn, etc., to form their salts with the liberation of hydrogen.

c. Action with alkalies: formation of salts
Carboxylic acids neutralize alkalies forming salts and water.

d. Action with carbonates and bicarbonates: evolving carbon dioxide
Carboxylic acids decompose carbonates and bicarbonates evolving carbon dioxide with brisk effervescence.


Mechanism of acidic character


In the COOH group due to resonance in the OH, O acquires some positive charge the electron pair of OH is drawn towards O. This displacement of electrons causes the release of a proton and a carboxylate ion, RCOO- is formed. This is the reason for acidic character of carboxylic acids.

The strength of acids can be expressed in terms of dissociation constant Ka or Ph number of PKa number which is pKa = -log Ka

A stronger acid will have a higher Ka value but smaller PKa value.

Effects of substituents on acidic strength of acids

Electron releasing substituents: Alkyl is an electron releasing group. If the H atom of formic acid (HCOOH) is replaced by CH3 group to form acetic acid (CH3COOH) the alkyl group will tend to increase the electron density on the oxygen atom of the O-H bond. This increase will make removal H+ ion difficult in comparison to formic acid.

Acetic acid is a weaker acid in comparison to formic acid.

The electron release effect is called +I effect. As +I effect increases, acidic strength will go down. As more alkyl groups are there +I effect increases
CH3
Therefore acidic property is stronger or more for CH3COOH.

Acidic strength is in the following order
acidic strength of HCOOH>CH3COOH>CH3CH2COOH>(CH3)2CHCOOH

Electron withdrawing substituents: Substituents like halogens tend to withdraw the electron charge. Halogens are electron attracting atoms(-I inductive effect). They withdraw the electrons from the carbon to which they are attached and this effect is transmitted throught the chain. The increases positive charge on O atom in the O-H bond and dissociation of H+ ion or proton takes place more easily.

Hence chloroacetic acid is stronger acid than acetic acid.

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Chemical equilibrium
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IIT JEE Revision - Ch.28 Carboxylic Acid - Core Points

JEE syllabus

Carboxylic acids:
Preparation, properties
Characteristic reactions
formation of esters,
acid chlorides and amides,
ester hydrolysis;


---------
1. Carboxylic acids are the compound containing carboxyl group in their molecules.

-C with a double bond with oxygen and single bond with OH

2. These acids can be aliphatic or aromatic.

aliphatic acids:

Formic acid HCOOH
Acetic acid CH-3COOH
Isobutyric acid (Branched)

aromatic acids

Bezoic acid : H in benzene substituted by COOH

m-Nitrobenzoic acid: One more H substituted by NO-2

o-Toluic acid (o refers to ortho) Benzoic acid with one more H substituted by CH-3

3. Methods of Preparation of Monocarboxylic Acids:
1. From oxidation of primary alcohols
2. By oxidation of aldehydes and ketones.


A. Reactions due to hydrogen atom of carboxyl group

1. Acidic character

a. Action with blue litmus
all carboxylic acids turn blue litmus red.


b. Reaction with metals: liberation of hydrogen
Carboxylic acids react with active metals such as Na, K, Ca, Mg, Zn, etc., to form their salts with the liberation of hydrogen.

c. Action with alkalies: formation of salts
Carboxylic acids neutralize alkalies forming salts and water.

d. Action with carbonates and bicarbonates: evolving carbon dioxide
Carboxylic acids decompose carbonates and bicarbonates evolving carbon dioxide with brisk effervescence.


Mechanism of acidic character


In the COOH group due to resonance in the OH, O acquires some positive charge the electron pair of OH is drawn towards O. This displacement of electrons causes the release of a proton and a carboxylate ion, RCOO- is formed. This is the reason for acidic character of carboxylic acids.

The strength of acids can be expressed in terms of dissociation constant Ka or Ph number of PKa number which is pKa = -log Ka

A stronger acid will have a higher Ka value but smaller PKa value.

Effects of substituents on acidic strength of acids

Electron releasing substituents: Alkyl is an electron releasing group. If the H atom of formic acid (HCOOH) is replaced by CH3 group to form acetic acid (CH3COOH) the alkyl group will tend to increase the electron density on the oxygen atom of the O-H bond. This increase will make removal H+ ion difficult in comparison to formic acid.

Acetic acid is a weaker acid in comparison to formic acid.

The electron release effect is called +I effect. As +I effect increases, acidic strength will go down. As more alkyl groups are there +I effect increases
CH3
Therefore acidic property is stronger or more for CH3COOH.

Acidic strength is in the following order
acidic strength of HCOOH>CH3COOH>CH3CH2COOH>(CH3)2CHCOOH

Electron withdrawing substituents: Substituents like halogens tend to withdraw the electron charge. Halogens are electron attracting atoms(-I inductive effect). They withdraw the electrons from the carbon to which they are attached and this effect is transmitted throught the chain. The increases positive charge on O atom in the O-H bond and dissociation of H+ ion or proton takes place more easily.

Hence chloroacetic acid is stronger acid than acetic acid.



Some more topics need to be covered


Carboxylic acid - practice questions
http://makoxmcqs.com/chemistry-mcqs-for-jee-main-carboxylic-acids-and-their-derivatives-mcq-practice-sheet/


Updated on 18 January 2020
5 February  2008

JEE Main Chemistry 2020 Syllabus - Revision Notes

 IIT JEE Main Chemistry syllabus

SECTION: A

PHYSICAL CHEMISTRY

UNIT 1: SOME BASIC CONCEPTS IN CHEMISTRY

Matter and its nature, Dalton’s atomic theory; Concept of atom, molecule, element and compound; Physical quantities and their measurements in Chemistry, precision and accuracy, significant figures, S.I. Units, dimensional analysis; Laws of chemical combination; Atomic and molecular masses, mole concept, molar mass, percentage composition, empirical and molecular formulae; Chemical equations and stoichiometry.

UNIT 2: STATES OF MATTER

Classification of matter into solid, liquid and gaseous states
Gaseous State: Measurable properties of gases; Gas laws – Boyle’s law, Charle’s law, Graham’s law of diffusion, Avogadro’s law, Dalton’s law of partial pressure; Concept of Absolute scale of temperature; Ideal gas equation; Kinetic theory of gases (only postulates); Concept of average, root mean square and most probable velocities; Real gases, deviation from Ideal behaviour, compressibility factor and van der Waals equation.
Liquid State: Properties of liquids – vapour pressure, viscosity and surface tension and effect of temperature on them (qualitative treatment only).
Solid State: Classification of solids: molecular, ionic, covalent and metallic solids, amorphous and crystalline solids (elementary idea); Bragg’s Law and its applications; Unit cell and lattices, packing in solids (fcc, bcc and hcp lattices), voids, calculations involving unit cell parameters, imperfection in solids; Electrical, magnetic and dielectric properties.

UNIT 3: ATOMIC STRUCTURE

Thomson and Rutherford atomic models and their limitations; Nature of electromagnetic radiation, photoelectric effect; Spectrum of hydrogen atom, Bohr model of hydrogen atom – its postulates, derivation of the relations for energy of the electron and radii of the different orbits, limitations of Bohr’s model; Dual nature of matter, de-Broglie’s relationship, Heisenberg uncertainty principle
Elementary ideas of quantum mechanics, a quantum mechanical model of the atom, its important features
Concept of atomic orbitals as one electron wave functions; Variation of Ψ and Ψ2 with r for 1s and 2s orbitals; various quantum numbers (principal, angular momentum and magnetic quantum numbers) and their significance; shapes of s, p and d – orbitals, electron spin and spin quantum number; Rules for filling electrons in orbitals – Aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of elements, extra stability of half-filled and completely filled orbitals.

UNIT 4: CHEMICAL BONDING AND MOLECULAR STRUCTURE

Kossel – Lewis approach to chemical bond formation, the concept of ionic and covalent bonds.
Ionic Bonding: Formation of ionic bonds, factors affecting the formation of ionic bonds; calculation of lattice enthalpy.
Covalent Bonding: Concept of electronegativity, Fajan’s rule, dipole moment; Valence Shell Electron Pair Repulsion (VSEPR) theory and shapes of simple molecules. Quantum mechanical approach to covalent bonding: Valence bond theory – Its important features, the concept of hybridisation involving s, p and d orbitals; Resonance.
Molecular Orbital Theory – Its important features, LCAOs, types of molecular orbitals (bonding, antibonding), sigma and pi-bonds, molecular orbital electronic configurations of homonuclear diatomic molecules, the concept of bond order, bond length and bond energy.
Elementary idea of metallic bonding. Hydrogen bonding and its applications.

UNIT 5: CHEMICAL THERMODYNAMICS

Fundamentals of thermodynamics: System and surroundings, extensive and intensive properties, state functions, types of processes.
First law of thermodynamics – Concept of work, heat internal energy and enthalpy, heat capacity, molar heat capacity; Hess’s law of constant heat summation; Enthalpies of bond dissociation, combustion, formation, atomization, sublimation, phase transition, hydration, ionisation and solution.
The second law of thermodynamics; Spontaneity of processes; ΔS of the universe and ΔG of the system as criteria for spontaneity, Δg° (Standard Gibbs energy change) and equilibrium constant

UNIT 6: SOLUTIONS

Different methods for expressing concentration of solution – molality, molarity, mole fraction, percentage (by volume and mass both), vapour pressure of solutions and Raoult’s Law – Ideal and non-ideal solutions, vapour pressure – composition, plots for ideal and non-ideal solutions; Colligative properties of dilute solutions – relative lowering of vapour pressure, depression of freezing point, elevation of boiling point and osmotic pressure; Determination of molecular mass using colligative properties; Abnormal value of molar mass, van’t Hoff factor and its significance.

UNIT 7: EQUILIBRIUM

https://iit-jee-chemistry.blogspot.com/2015/05/jee-main-core-points-for-revision.html

Meaning of equilibrium, the concept of dynamic equilibrium

Equilibria involving physical processes: Solid-liquid, liquid – gas and solid – gas equilibria, Henry’s law, general characteristics of equilibrium involving physical processes.

Equilibria involving chemical processes: Law of chemical equilibrium, equilibrium constants (Kp and Kc) and their significance, the significance of ΔG and ΔG° in chemical equilibria, factors affecting equilibrium concentration, pressure, temperature, the effect of catalyst; Le Chatelier’s principle.

Ionic equilibrium: Weak and strong electrolytes, ionization of electrolytes, various concepts of acids and bases (Arrhenius, Bronsted – Lowry and Lewis) and their ionization, acid-base equilibria (including multistage ionization) and ionization constants, ionization of water, pH scale, common ion effect, hydrolysis of salts and pH of their solutions, solubility of sparingly soluble salts and solubility products, buffer solutions.


UNIT 8: REDOX REACTIONS AND ELECTROCHEMISTRY

Electronic concepts of oxidation and reduction, redox reactions, oxidation number, rules for assigning oxidation number, balancing of redox reactions
Electrolytic and metallic conduction, conductance in electrolytic solutions, specific and molar conductivities and their variation with concentration: Kohlrausch’s law and its applications.
Electrochemical cells – Electrolytic and Galvanic cells, different types of electrodes, electrode potentials including standard electrode potential, half – cell and cell reactions, emf of a Galvanic cell and its measurement; Nernst equation and its applications; Relationship between cell potential and Gibbs’ energy change; Dry cell and lead accumulator; Fuel cells.


UNIT 9: CHEMICAL KINETICS

Rate of a chemical reaction, factors affecting the rate of reactions: concentration, temperature, pressure and catalyst; elementary and complex reactions, order and molecularity of reactions, rate law, rate constant and its units, differential and integral forms of zero and first order reactions, their characteristics and half-lives, effect of temperature on rate of reactions – Arrhenius theory, activation energy and its calculation, collision theory of bimolecular gaseous reactions (no derivation).

UNIT-10: SURFACE CHEMISTRY

Adsorption – Physisorption and chemisorption and their characteristics, factors affecting the adsorption of gases on solids – Freundlich and Langmuir adsorption isotherms, adsorption from solutions.

Colloidal state – distinction among true solutions, colloids and suspensions, classification of colloids – lyophilic, lyophobic; multi molecular, macromolecular and associated colloids (micelles), preparation and properties of colloids – Tyndall effect, Brownian movement, electrophoresis, dialysis, coagulation and flocculation; Emulsions and their characteristics.

Chemistry Syllabus for IIT JEE Main

SECTION – B

INORGANIC CHEMISTRY

UNIT 11: CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

Modem periodic law and present form of the periodic table, s, p, d and f block elements, periodic trends in properties of elements atomic and ionic radii, ionisation enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity.c

UNIT 12: GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF METALS

Modes of occurrence of elements in nature, minerals, ores; Steps involved in the extraction of metals – concentration, reduction (chemical and electrolytic methods) and refining with special reference to the extraction of Al, Cu, Zn and Fe; Thermodynamic and electrochemical principles involved in the extraction of metals.

UNIT 13: HYDROGEN

Position of hydrogen in periodic table, isotopes, preparation, properties and uses of hydrogen; Physical and chemical properties of water and heavy water; Structure, preparation, reactions and uses of hydrogen peroxide; Hydrogen as a fuel

UNIT 14: S – BLOCK ELEMENTS (ALKALI AND ALKALINE EARTH METALS)

Group – 1 and 2 Elements

General introduction, electronic configuration and general trends in physical and chemical properties of elements, anomalous properties of the first element of each group, diagonal relationships
Preparation and properties of some important compounds – sodium carbonate and sodium hydroxide; Industrial uses of lime, limestone, Plaster of Paris and cement; Biological significance of Na, K, Mg and Ca.


UNIT 15: P – BLOCK ELEMENTS

Group – 13 to Group 18 Elements

General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups; unique behaviour of the first element in each group.

Group-wise study of the p – block elements

Group – 13: Preparation, properties and uses of boron and aluminium; properties of boric acid, diborane, boron trifluoride, aluminium chloride and alums.
Group – 14: Allotropes of carbon, the tendency for catenation; Structure; properties of silicates, and zeolites.
Group – 15: Properties and uses of nitrogen and phosphorus; Allotrophic forms of phosphorus; Preparation, properties, structure and uses of ammonia, nitric acid, phosphine and phosphorus halides, (PCl3, PCl5); Structures of oxides and oxoacids of phosphorus.
Group – 16: Preparation, properties, structures and uses of ozone; Allotropic forms of sulphur; Preparation, properties, structures and uses of sulphuric acid (including its industrial preparation); Structures of oxoacids of sulphur.
Group – 17: Preparation, properties and uses of hydrochloric acid; Trends in the acidic nature of hydrogen halides; Structures of Interhalogen compounds and oxides and oxoacids of halogens.
Group –18: Occurrence and uses of noble gases; Structures of fluorides and oxides of xenon.


UNIT 16: d – and f – BLOCK ELEMENTS

Transition Elements

General introduction, electronic configuration, occurrence and characteristics, general trends in properties of the first row transition elements – physical properties, ionization enthalpy, oxidation states, atomic radii, colour, catalytic behaviour, magnetic properties, complex formation, interstitial compounds, alloy formation; Preparation, properties and uses of K2 Cr2 O7 and KMnO4 .
Inner Transition Elements
Lanthanoids – Electronic configuration, oxidation states and lanthanoid contraction.
Actinoids – Electronic configuration and oxidation states.

UNIT 17: CO-ORDINATION COMPOUNDS

Introduction to co-ordination compounds, Werner’s theory; ligands, coordination number, denticity, chelation; IUPAC nomenclature of mononuclear co-ordination compounds, isomerism; Bonding-Valence bond approach and basic ideas of Crystal field theory, colour and magnetic properties; Importance of coordination compounds (in qualitative analysis, extraction of metals and in biological systems).

UNIT 18: ENVIRONMENTAL CHEMISTRY

Environmental pollution – Atmospheric, water and soil.
Atmospheric pollution – Tropospheric and Stratospheric
Tropospheric pollutants – Gaseous pollutants: Oxides of carbon, nitrogen and sulphur, hydrocarbons; their sources, harmful effects and prevention; Greenhouse effect and Global warming; Acid rain;
Particulate pollutants: Smoke, dust, smog, fumes, mist; their sources, harmful effects and prevention.
Stratospheric pollution- Formation and breakdown of ozone, depletion of ozone layer – its mechanism and effects.
Water Pollution – Major pollutants such as pathogens, organic wastes and chemical pollutants; their harmful effects and prevention.
Soil pollution – Major pollutants such as Pesticides (insecticides, herbicides and fungicides), their harmful effects and prevention.
Strategies to control environmental pollution.

SECTION-C

ORGANIC CHEMISTRY

UNIT 19: PURIFICATION AND CHARACTERISATION OF ORGANIC COMPOUNDS

Purification – Crystallization, sublimation, distillation, differential extraction and chromatography – principles and their applications

Qualitative analysis – Detection of nitrogen, sulphur, phosphorus and halogens

Quantitative analysis (basic principles only) – Estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus

Calculations of empirical formulae and molecular formulae; Numerical problems in organic quantitative analysis

UNIT 20: SOME BASIC PRINCIPLES OF ORGANIC CHEMISTRY

Tetravalency of carbon; Shapes of simple molecules – hybridisation (s and p); Classification of organic compounds based on functional groups: – C = C –, – C h C – and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism – structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)

Covalent bond fission – Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.

Electronic displacement in a covalent bond – Inductive effect, electromeric effect, resonance and hyperconjugation

UNIT 21: HYDROCARBONS

Classification, isomerism, IUPAC nomenclature, general methods of preparation, properties and reactions.

Alkanes – Conformations: Sawhorse and Newman projections (of ethane); Mechanism of halogenation of alkanes.

Alkenes – Geometrical isomerism; Mechanism of electrophilic addition:
Addition of hydrogen, halogens, water, hydrogen halides (Markownikoff’s and peroxide effect); Ozonolysis and polymerisation.

Alkynes – Acidic character; Addition of hydrogen, halogens, water and hydrogen halides; Polymerization.

Aromatic hydrocarbons – Nomenclature, benzene – structure and aromaticity; Mechanism of electrophilic substitution: halogenation, nitration, Friedel – Craft’s alkylation and acylation, directive influence of functional group in mono-substituted benzene.

UNIT 22: ORGANIC COMPOUNDS CONTAINING HALOGENS

General methods of preparation, properties and reactions; Nature of C-X bond; Mechanisms of substitution reactions. Uses; Environmental effects of chloroform - iodoform.


UNIT 23: ORGANIC COMPOUNDS CONTAINING OXYGEN

General methods of preparation, properties, reactions and uses

ALCOHOLS, PHENOLS AND ETHERS

Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.

Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer – Tiemann reaction.

Ethers: Structure.

Aldehyde and Ketones: Nature of carbonyl group;Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as – Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of α – hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.

Carboxylic acids: Acidic strength and factors affecting it.

UNIT 24: ORGANIC COMPOUNDS CONTAINING NITROGEN

General methods of preparation, properties, reactions and uses

Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.

Diazonium Salts: Importance in synthetic organic chemistry.

UNIT 25: POLYMERS

General introduction and classification of polymers, general methods of polymerisation - addition and condensation, copolymerization; Natural and synthetic rubber and vulcanisation; some important polymers with emphasis on their monomers and uses – polyethene, nylon, polyester and bakelite

UNIT 26: BIOMOLECULES

General introduction and importance of biomolecules

CARBOHYDRATES – Classification: aldoses and ketoses; monosaccharides (glucose and fructose) and constituent monosaccharides of oligosaccharides (sucrose, lactose and maltose)
PROTEINS – Elementary Idea of  – amino acids, peptide bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes.
VITAMINS – Classification and functions.
NUCLEIC ACIDS – Chemical constitution of DNA and RNA. Biological functions of nucleic acids.

UNIT 27: CHEMISTRY IN EVERYDAY LIFE

Chemicals in medicines – Analgesics, tranquillisers, antiseptics, disinfectants, antimicrobials, antifertility drugs, antibiotics, antacids, antihistamines – their meaning and common examples
Chemicals in food – Preservatives, artificial sweetening agents – common examples
Cleansing agents – Soaps and detergents, cleansing action


UNIT 28: PRINCIPLES RELATED TO PRACTICAL CHEMISTRY

Detection of extra elements (N, S, halogens) inorganic compounds;

Detection of the following functional groups: hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketone), carboxyl and amino groups in organic compounds.

The chemistry involved in the preparation of the following:
Inorganic compounds: Mohr’s salt, potash alum.
Organic compounds: Acetanilide, pnitroacetanilide, aniline yellow, iodoform.

The chemistry involved in the titrimetric exercises – Acids bases and the use of indicators, oxalic-acid vs KMnO4, Mohr’s salt vs KMnO4.

Chemical principles involved in the qualitative salt analysis:

Cations – Pb2+, Cu2+, AI3+, Fe3+, Zn2+, Ni2+, Ca2+, Ba2+, Mg2+, NH4+.

Anions- CO3 2-, S2-, SO4 2-, NO2-, NO3-, CI -, Br, I. (Insoluble salts excluded).


Chemical principles involved in the following experiments:

Enthalpy of solution of CuSO4
Enthalpy of neutralisation of strong acid and strong base.
Preparation of lyophilic and lyophobic sols.
Kinetic study of the reaction of iodide ion with hydrogen peroxide at room temperature.


Updated 15 Jan 2020, 12 January 2020
9 Jan 2020

JEE Main 2020 - ORGANIC CHEMISTRY Syllabus and Revision Points - Index

ORGANIC CHEMISTRY

UNIT 19: PURIFICATION AND CHARACTERISATION OF ORGANIC COMPOUNDS

Purification – Crystallization, sublimation, distillation, differential extraction and chromatography – principles and their applications

Qualitative analysis – Detection of nitrogen, sulphur, phosphorus and halogens

Quantitative analysis (basic principles only) – Estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus

Calculations of empirical formulae and molecular formulae; Numerical problems in organic quantitative analysis

UNIT 20: SOME BASIC PRINCIPLES OF ORGANIC CHEMISTRY

Tetravalency of carbon; Shapes of simple molecules – hybridisation (s and p); Classification of organic compounds based on functional groups: – C = C –, – C h C – and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism – structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)

Covalent bond fission – Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.

Electronic displacement in a covalent bond – Inductive effect, electromeric effect, resonance and hyperconjugation

UNIT 21: HYDROCARBONS

Classification, isomerism, IUPAC nomenclature, general methods of preparation, properties and reactions.

Alkanes – Conformations: Sawhorse and Newman projections (of ethane); Mechanism of halogenation of alkanes.

Alkenes – Geometrical isomerism; Mechanism of electrophilic addition:
Addition of hydrogen, halogens, water, hydrogen halides (Markownikoff’s and peroxide effect); Ozonolysis and polymerisation.

Alkynes – Acidic character; Addition of hydrogen, halogens, water and hydrogen halides; Polymerization.

Aromatic hydrocarbons – Nomenclature, benzene – structure and aromaticity; Mechanism of electrophilic substitution: halogenation, nitration, Friedel – Craft’s alkylation and acylation, directive influence of functional group in mono-substituted benzene.

UNIT 22: ORGANIC COMPOUNDS CONTAINING HALOGENS

General methods of preparation, properties and reactions; Nature of C-X bond; Mechanisms of substitution reactions. Uses; Environmental effects of chloroform - iodoform.


UNIT 23: ORGANIC COMPOUNDS CONTAINING OXYGEN

General methods of preparation, properties, reactions and uses

ALCOHOLS, PHENOLS AND ETHERS

Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.

Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer – Tiemann reaction.

Ethers: Structure.

Aldehyde and Ketones: Nature of carbonyl group;Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as – Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of α – hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.

Carboxylic acids: Acidic strength and factors affecting it.

UNIT 24: ORGANIC COMPOUNDS CONTAINING NITROGEN

General methods of preparation, properties, reactions and uses

Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.

Diazonium Salts: Importance in synthetic organic chemistry.

UNIT 25: POLYMERS

General introduction and classification of polymers, general methods of polymerisation - addition and condensation, copolymerization; Natural and synthetic rubber and vulcanisation; some important polymers with emphasis on their monomers and uses – polyethene, nylon, polyester and bakelite

UNIT 26: BIOMOLECULES

General introduction and importance of biomolecules

CARBOHYDRATES – Classification: aldoses and ketoses; monosaccharides (glucose and fructose) and constituent monosaccharides of oligosaccharides (sucrose, lactose and maltose)
PROTEINS – Elementary Idea of  – amino acids, peptide bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes.
VITAMINS – Classification and functions.
NUCLEIC ACIDS – Chemical constitution of DNA and RNA. Biological functions of nucleic acids.

Group 17 Halogens

Elements

Flourine (z = 9, 2p5)
Chlorine (z = 17, 3p5)
Bromine (z = 35, 4p5)
Iodine (z = 53, 5p5)
At (z = 85, 6p5)

Covalent bond fission – Homolytic and heterolytic

Organic reactions usually involve making and breaking of covalent bonds. The fission of bonds can take place in two ways.

Bond breaking is also known as bond fission.

1. Homolytic fission
2. Heterolytic fission
----------------
Heterolytic fission results in the formation of two different chemical species in the sense that one is a cation and the other an anion.

Homolytic fission results in two electrically uncharged radicals.

Radicals have an unpaired electron.
Radicals are particles that have an unpaired electron. They may be single atoms (e.g. chlorine radical, Cl.) or groups of covalently bonded atoms (e.g. methyl radical,.CH3).

Some radicals, called biradicals, have two unpaired electrons, for example, .O. (1s22s22p4) and .O2..

Because of the unpaired electron, radicals can be very reactive. However, there are some that are relatively stable and behave somewhat like ordinary molecules. An example is nitrogen monoxide.

Heterolytic fission versus Homolytic fission...

The hydrogen chloride molecule (H-Cl) is polar owing to the greater electronegativity of the chlorine atom. Heterolytic fission is more common where a chemical bond is already polar. Hydrogen chloride is highly soluble in water and becomes fully ionised; it is a strong acid. Solvents with polar molecules favour heterolytic fission.

Homolyic fission is favoured by non-polar solvents, or by gaseous conditions, and the presence of visible or ultraviolet light.

http://www.avogadro.co.uk/light/fission/bondfission.htm
---------------

Reaction Intermediates

The species produced during cleavage of bonds are called reaction intermediates. The important ones are:

1. Free radical: A free radical is an atom or group of atoms having an unpaired electron. Thee are produced during the homolytic fission of a covalent bond. These are very reactive. The free radicals are classified as primary, secondary or tertiary depending upon whether one, two or three carbon atoms are attached to the carbon atom carrying the odd electron.

The order of stability of alkyl free radicals is

cH3<1 br="">
2. carbocation: It is a group of atoms which contain positively charged carbon having only six electrons. It is obtained by heterolytic fission of covalent bond involving carbon atoms.

Relative stabilty: The methyl group has +I inductive effect. So the alkyl group (as a specific example methyl group)attached to +vely charged carbon (carbocation) tends to releaase electrons towards carbon. As a result, it decreases +charge on the carbocation. Due to this inductive effect, the positive charge on the carbocation gets reduced and dispersed (Dispersion is distribution of charge over other atoms in the molecule). The dispersal of charge results into stability. Therefore, more the number of alkyl groups, the greater will be the dispersal of charge and therefore, more stable will be the carbocation.

So the order of stabilty is

CH3^+<1 br="">
3. Carbanion: It is a species containing a carbon atom carrying a negative charge. They are generated during heterolytic fission of covalent bonds containing carbon, when an atom linked to carbon goes without the bonding electrons.

Carbanions are very reactive species.

They are classified as primary, secondary and tertiary.

The order of stability is reverse of that of carbocations and free radicals.

CH3‾ >1°>2°>3°

4. carbene: The carbenes are reactive neutral species in which the carbon atom has six electrons in the valence shell out of which two are shared. The simplest carbene is methylene (:CH2). It is formed wbehg diazomethan is decomposed by the action of light.

CH2N2 --> :CH2 + N2

Types of attacing reagents

1. Free radicals
2. Electrophiles
3. Nucleophiles


Typesof organic reactions

1. substitution reactions
2. Addition reactions
3. Elimination reactions
--i) α-Elimination
--ii) β-Elimination
--iii)γ-Elimination
4. Rearrangement reactions
5. Condensation reactions
6. Isomerism reactions

Isomerism - Structural isomerism

Isomerism: Organic compounds exhibit isomerism. Isomerism is a phenomenon that describes the fact two compounds having same molecular formula have different physical and chemical properties.
12. Structural isomerism and stereo isomerism are two major categories in isomerism.

Homologous Series

Homologous Series: A series of similarly constituted compounds containing the same functional group and have similar chemical charateristics.

Phenol - Reimer-Tiemann reaction

 Reimer-Tiemann reaction:
When phenol is refluxed with chloroform in the presence of acqueous sodium hydroxide at 340 K followed by hydrolysis, an aldehydic group (HC=O) gets introduced in the ring at a position ortho to the phenolic group. So ortho hydroxy bezaldehyde is formed. It is also called salicylaldehyde.

Identification of primary, secondary and tertiary alcohols - Lucas test

Lucas test

Reaction with ZnCl2/conc.-HCl

This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.

In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).

Alkynes - Polymerization

Polymerization

a) Acytylene dimerizes (two molecules come together as one molecule) in the presence of cuprous chloride and ammonium chloride to give vinyl acetylene which on reacting with HCl gives chloroprene.

The later polymerizes to give neoprene - a synthetic rubber.

b) Cyclic polymerization

This takes place when alkyne is passed through red hot iron tube at 400 degress celsius.

Occurs in two stages. Acetylene becomes mesitylene.

IIt JEE Revision Ch.26 Alkyl and Aryl Halides - Core Points

syllabus


METHODS OF PREPARATION
PHYSICAL PROPERTIES
CHEMICAL REACTIONS
charateristic reactions

Specially highlighed topics

Rearrangement reactions of alkyl carbocation,
Grignard reactions,
Nucleophilic substitution reactions;
-------------

1. When hydrogen atom or atoms of alkanes are replaced by the corresponding number of halogen atoms, the compounds are called halogen derivatives of alkanes.



2. Methods of preparation

1. From hydrocarbons
a) from alkanes: halogens react with alkanes in the presence of uv light to form haloalkanes.
b) from alkenes: by the electrophylic addition of halogen acids (HBr, HCl, or HI)

3. The only methyl halide which is a liquid is iodomethane.  chloroethane is a gas.

4. Nucleophilic substitution in primary halogenoalkanes
The nucleophilic substitution reaction - an SN2 reaction - S stands for substitution, N for nucleophilic, and the 2 is order of reaction. It is because the initial stage of the reaction involves two species - the bromoethane and the Nucleophilic (Nu-) ion.

5. Nucleophilic substitution in tertiary halogenoalkanes - The nucleophilic substitution reaction - an SN1 reaction (1 denotes 1st order)

6.


2020 Presentation

Haloalkanes and Haloarenes

1. The groups which possess two nucleophilic centres are called ambident nucleophiles.

Explanation: An ambident nucleophile has "teeth" on two sides.

It can attack from two different places and form two different products.

For example, the thiocyanate ion, SCN⁻, is a ambident nucleophile. It is a resonance hybrid.

Both the S  and the N  atoms can act as nucleophiles.

So, the SN2  reaction of an alkyl halide with SCN⁻  often leads to a mixture of an alkyl thiocyanate and an alkyl isothiocyanate.

R-X+SCN⁻→X⁻   + R-SCN          + R-NCS
                alkyl            alkyl
                thiocyanate      isothiocyanate
https://socratic.org/questions/what-is-an-ambident-nucleophile


2. The rate of reaction depends on the concentration of both alkyl halid and base, the reation is known as SN2 reactions.

3. The rate of reaction depends on the concentration of alkyl halides, the reaction is known as SN1 reaction.

4. The order of reactivity of alkyl halides for SN1 reactions

3 degree halide > 2 degree halide > 1 degree halide > CH3X
(tertiary)              (secondary)           (primary)

5. The order of reactivity of alkyl halides for SN2 reactions

3 degree halide < 2 degree halide < 1 degree halide < CH3X

6.  In SN1 and SN2 mechanism, the reactivity of halides follows the order

R-I > R-Br > R-Cl > R-F

7. If all the substituents attached to a carbon are different, that carbon is called asymmetric (or) Chiral carbon or stereocentre.

8. The stereo isomers related to each other as non-super imposable images are called enantiomers.

9. A mixture containing two enantiomers in equal proportions will have zero optical rotation, as the rotation due to one isomer will be exactly cancelled by the rotation due to the other isomer. Such a mixture is known as racemic mixture or racemic modification.

10. The process of conversion of enantiomer into a racemic mixture is known as racemisation.


Key words:  ambident nucleophiles, SN2 reactions, SN1 reaction, The order of reactivity of alkyl halides for SN1 reactions (degree of halides),  The order of reactivity of alkyl halides for SN2 reactions(degree of halides), order of  reactivity of halides (based on halogen), asymmetric (or) Chiral carbon or stereocentre, enantiomers, racemic mixture or racemic modification, racemisation.


Updated on 12 January 2020.
2 May 2008

IIT JEE Revision Alkanes Halogenation

Halogenation of alkanes

This involves substitution of hydrogen atom by halogen atom. The order of reactivity is F2>Cl2.>Br2>I2.

The mechanism of chlorination and bromination involves free radicals.

Step 1 (Initiation)

Heat or uv light cause the weak halogen bond to undergo homolytic cleavage to generate two bromine radicals and starting the chain process.

Step 2 (Propagation)

(a) A bromine radical abstracts a hydrogen to form HBr and a methyl radical, then
(b) The methyl radical abstracts a bromine atom from another molecule of Br2 to form the methyl bromide product and another bromine radical, which can then itself undergo reaction 2(a) creating a cycle that can repeat.

Step 3 (Termination)
Various reactions between the possible pairs of radicals allow for the formation of ethane, Br2 or the product, methyl bromide. These reactions remove radicals and do not perpetuate the cycle. There will be equilibrium and reaction terminates.

Updated on 11 January 2020
28 January 2008

IIT JEE Revision Ch. 22/15 Alkenes - Core Chapter Points

Syllabus

Preparation, properties and reactions of alkenes:

Preparation of alkenes by elimination reactions;
Physical properties: boiling points, density and dipole moments
Acidity;
Acid catalysed hydration of alkenes(excluding the stereochemistry of addition and elimination);
Reactions of alkenes with KMnO4 and
Reactions of alkenes with ozone;
Reduction of alkenes;
Electrophilic addition reactions of alkenes with X2, HX, HOX and H2O (X=halogen);
---------------

Introduction

Alkenes are unsaturated hydrocarbons having carbon-carbon double bond(C=C) in their molecules.

Their general formula is C-nH-2n.
The simplest alkene is ethene, C-2H-4

15.9 Preparation and Properties of Alkenes

Methods of Preparation

1. Dehydrohalogenation of alkyl halides.

2. Dehydration of alcohols

3. Dehalogenation of vicinal dihalides

Physical properties

State: Ethene, propene and butene are gases at room temperature. From pentene onwards till alkenes having 18 carbon atoms, they are liquids. Still higher members of the family are solids.

Chemical Reactions of Alkenes

Addition of water

Water adds to alkenes in the presence of mineral acids. Hence it is termed catalytic hydration of alkenes. Addition occurs in accordance with Markownikov's rule. We get alcohols from this addition.

Oxidation with potassium permanganate (specially mentioned in syllabus)
Alkenes react with cold dilute potassium permanganate solution(alkaline) to form 1,2-diols called glycols. The glycols contain two -OH groups on adjacent carbon atoms.

Reaction with ozone

Ozone, O3, is an allotrope of oxygen that adds rapidly to carbon-carbon double bonds. Since the overall change in ozonolysis is more complex than a simple addition reaction, its mechanism has been extensively studied. Reactive intermediates called ozonides have been isolated from the interaction of ozone with alkenes, and these unstable compounds may be converted to stable products by either a reductive workup (Zn dust in water or alcohol) or an oxidative workup (hydrogen peroxide).


Reduction
Addition of hydrogen to a carbon-carbon double bond is called hydrogenation. The overall effect of such an addition is the reductive removal of the double bond functional group.

Polymerisation
-- polymerisation of ethene
-- polymerisation of vinyl chloride
-- polymerisation of styrene

Addition of hydrogen to a carbon-carbon double bond is called hydrogenation. The overall effect of such an addition is the reductive removal of the double bond functional group.

15.7 Isomerism in Alkenes

Alkenes show the following types of strunctural isomerism

1. Structural isomerism: Alkenes show chain isomerism and position isomerism.

a. Chain isomerism: C-4H-8 exists as two chain isomers, n-Butene and Isobutene.

b. Position isomerism: The isomers differ in the position of the double bonds. C-4H-8 can have the double bond as the terminal bond or it can be in the middle. The one with the terminal bond is n-Butene and the one with the double bond in the middle is but-2-ene. Thus butane with the structural formula C-4H-8 has three structural isomers.

Butane with the structural formula C-4H-8 has three structural isomers.

2. Geometrical isomerism: 
Alkenes exhibit geometrical isomerism.

Molecules of the type C₂A₂B₂ are available as geometrical isomers. The two atoms attached to the same carbon atom are different. In this symbols, A and B are different.

The molecule in which similar atons or groups lie on the same side of the double bond is called cis-isomer. Both As are attached to the carbon on one side of the double bond. Simiarly two Bs.


If they are attached on the opposite sides, it is a trans-isomer

Examples
CH₃HC=CHCH₃ exhibits geometrical isomerism.

As CH₃ and H are different groups

Maleic acid and Fumaric acid are geometrical isomers.
HOOCHC=CHCOOH

Cis isomer is maleic acid and trans isomer is fumaric acid.

If they are attached on the opposite sides, it is a trans-isomer



Jauhar Chapter 15 contents of Alkenes

Chemistry of Alkenes
15.6 Nomenclature of Alkenes
15.7 Isomerism in Alkenes
15.8 Stability of of Alkenes
15.9 Preparation and Properties of Alkenes


Updated om 11 January 2020
28 January 2008

Functional Groups of Organic Compounds

Functional group: Functional groups of structural features within a molecule that determine its reactivity. Thus a functional group is a group of atoms within a molecule that has a charateristic chemical behaviour. For illustration, the simplest functional group is the carbon-carbon double bond. Similarly carbon-carbon triple bond will be another functional group.


The important functional groups are:
Alkyl halide,
Alcohols,
Ethers,
Amines,

Thiol,
 Aldehyde,
Ketone,
Carboxylic acids,
Esters,
Acid halides,
Amides,
Nitriles.

________________



________________

http://www.youtube.com/watch?v=t4lIp0Z1mVg


Updated on 11 Jan 2020
17 December 2011

IIT JEE Ch. 4. PERIODICITY OF PROPERTIES OF ELEMENTS - Revision Points

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.


JEE Syllabus

Modem periodic law and present form of the periodic table, s, p, d and f block elements, periodic trends in properties of elements atomic and ionic radii, ionisation enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity.

Study Guide for the chapter - 20 day plan
http://iit-jee-chemistry.blogspot.in/2009/03/jee-study-guide-4-classification-of.html
------------

I want to paste the periodic table in this post. It is important to know the atomic numbers of many elements as well as the group wise elements and periodwise elements. Many times, the answers to questions can be given if we know to which group the elements in the question belong to by analogy to the behaviour of popular elements like Na, Mg, C,N,O,S, and F.

So periodic table is an essential revision






4.1 Development of Periodic Table

Mendeleeve's Periodic Table Video
10.4 minutes
_________________

_________________
ExamFearVideos


In 1869, Russian chemist Dmitry Mendeleev gave a law known as the periodic law based observations of physical and chemical properties of various elements known to exist at that time.

The law states that: "the physical and chemical properties of elements are periodic functions of their atomic masses."

4.2 Atomic Number and Modern Periodic Law

In 1942, Moseley, physicist of England discovered a relationship between X-ray spectra and the atomic number of elements.

The equation is SQRT(v) = a(z - b)

Where v is the frequency of the X-ray emitted by an elements and z is its atomic number.  a and b are constants.

He suggested atomic number as the basis of classification of elements.
Modern periodic law may be stated as: "the physical and chemical properties of elements are periodic function of their atomic numbers.

4.3 Electronic Configuration

4.4 The long Form of the Periodic Table

A horizontal row in the periodic table is called a period. The elements in a period have same number of electron shells i.e., principal quantum number (n). There are seven periods in the periodic table.

A vertical column in the periodic table is called a group. It constitutes series of elements who atoms have the same outermost electronic configuration.

4.5 Division of Elements into s, p, d, and f-Blocks

s-block elements: The elements in which the last electron enters the s-orbital of their outermost energy level are calleed s-block elements.

4.6 Periodic Properties

4.7 Atomic Radii

4.8 Ionic Radii

4.9 Ionization Enthalphy

4.10 Electron Gain Enthalpy

4.11 Valency


Sections in the Chapter


4.1 Development of Periodic Table
4.2 Atomic Number and Modern Periodic Law
4.3 Electronic Configuration
4.4 The long Form of the Periodic Table
4.5 Division of Elements into s, p, d, and f-Blocks
4.6 Periodic Properties
4.7 Atomic Radii
4.8 Ionic Radii
4.9 Ionization Enthalphy
4.10 Electron Gain Enthalpy
4.11 Valency


Updated on 9 January 2020,   8 Feb 2016,  21 May 2015
First Published on 19 Jan 2008

IIT JEE Main Chemistry Ch 1. THE CONCEPTS - Core Points for Review

Importance of  Core Revision Points: Core Revision Points are important because if you remember them strongly, many more points related to them will come out of your memory and help you to answer question and problems. Read them many times and make sure you remember them very strongly.



JEE Main Syllabus

1.1 Importance of Studying Chemistry

Chemistry is the study of the materials that make up the universe and the changes which these materials undergo. In chemistry, we study the composition of materials to find out what they are made of.  

Now we know that all the matter in the universe is made up of various elements, compounds and mixtures. Each element has tiny smallest particles called atoms and elements have their stable combination of atoms called molecules. Compounds are made up of molecules which in turn have various atoms of elements.

There are 112 elements.

Elements and compounds when mixed in appropriate conditions undergo changes and new compounds and materials get formed. There changes in the language of chemistry are called chemical reactions.

Chemistry as a subject has helped in providing creating more food, health care products and other necessities of life. It also provided various materials that provide us comforts, pleasure and luxuries. It provided us building materials and synthetic fibres. In recent, new materials such super-conducting ceramics, conducting polymers, optical fibres, microalloys, nanomaterials like carbon fibres were developed by chemistry scholars and scientists.  

Chemists are presently study chemical processes related to environmental damage by man made substances and bio-chemical processes to cure old age related diseases and malfunctions of the human body.

1.2 Physical quantities and their S.I. Units

SI (Systeme Internationale) units were adopted by General Conference of Weights and Measures in 1960. The SI system has seven basic units from which all other units are derived.

1.3 Dimensional Analysis

To convert one set of units say metres into another set of units say centimetres, conversion factor method is used. It is also called dimensional analysis.

Unit conversion factors are used in factor conversion method.

We know 1 m = 100 cm

So  1 = 100 cm/ 1 m  and this is called unit conversion factor between cm and m.

We can convert 25 metres into centimetres by writing 25 m (100 cm /1m) which will give 2500 cm. The metres dimension cancels out and cm dimension has come. So apart from numerical terms, dimensions are also multiplied or divided to get the required dimensions.

4. Measurement and significant figures

Accuracy
Accuracy is a measure of the difference between the true value (the value to be measured) and the value measured by an instrument.

Accuracy  = Mean of measurements - true value

Precision is depends totally on the instrument and it is the difference between measurements of the same dimension made number of times. It is expressed as the difference between one measurement and the arithmetic mean of the number of measurements.

Actual measurement value - mean of measurements

It can be understood as the lowest measurement - mean of measurements or highest measurement - mean of measurements

Significant figures: Significant figures in a number are include all the certain digits plus one doubtful digit.

If a number has 4 significant figures or digits, it means 3 of them are certain and fourth one is doubtful.

Rules for determining the number of significant figures

1. All non-zero digits are significant
Decimal place does not determine the number of significant figures.

2. A zero becomes significant in case it comes between two non-zero numbers.
3. The zeros at the beginning of a number are not significant.
For example 0.0004 has only one significant figure.
4. All zeros placed to right of a number are significant. They represent the precision of the measuring scale.
For example 267.000 has six significant figures.
(The precision does not come by writing the number. It comes because the instrument has the ability to read a number certainly up to that level of measurement.)

Rules of calculations involving significant figures
Rule 1. The final result of addition or subtraction should be reported up to the same number of decimal places as are present in the term having the least number of decimal places.
Example- addition of three numbers
6.414
2.3
0.501
------
9.215  answer but the answer should be reported up to one decimal place only as 2.3 is the term having least number of decimal places.

Hence correct answer is 9.2

Rule 2. In multiplication or division, the final result should be reported up to the same number of significant figures as are present in the term with the least number of significant figures.
Example: 4.2345*1.25 = 5.293125
The final result should be reported up to three significant figures only as 1.25 has three significant figures. Hence the correct answer to be reported is 5.29.

Rounding off figures of retention of significant figures.

i) If the digit coming after the desired number of significant figures happens to be more than 5, the preceding digit or figure is increased by 1.
ii) If that digit is less than 5, it is neglected and hence the preceding significant figure remains unchanged.
iii) If that digit happens to be 5, the preceding digit is increased by one in case it is odd number. If preceding digit is an even number, it remains the same.

If the problem has number of steps, the rounding off is to be done at the final answer level only.

5. Chemical classification of matter

1. Element
Further classification: Metals, non-metals, metalloids

2. Compound
Further classification: Inorganic and organic

3. Mixture
Further classification: Homogeneous mixtures - they are called solutions.
Heterogeneous mixtures: They have visible boundaries of separation between the different constituents and they can be easily seen with naked eye.

6. Laws of chemical combination

a. Law of conservation of mass
During any physical o chemical change, the total mass of the products is equal to the total mass of reactants.

b. Law of constant proportions
A pure chemical compound always contains same elements combined together in the same definite proportion by weight.

c. Law of multiple proportions
When two elements combine to form two or more than two compounds, the weights of one of the elements which combine with a fixed weight of the other, bear a simple whole number ratio.

d. Law of reciprocal proportions
When two different elements combine separately with the same weight of a third element, the ratio in which they do so will be the same or some simple multiple of the ratio in which they combine with each other.

e. Gay Lussac’s law of combing volumes
Under similar conditions of temperature and pressure, whenever gases react together, the volumes of the reacting gases as well as products (if gases) bear a simple whole number ratio.

7. Dalton’s atomic theory

To provide theoretical justification to the laws of chemical combination which are experimentally verified, John Dalton postulated a simple theory of matter. The basic postulates of Dalton’s atomic theory are:

a. Matter is made up of extremely small indivisible and indestructible ultimate particles called atoms.
b. Atoms the same element are identical in all respects ie., in shape, size, mass and chemical properties.
c. Atoms of different elements are different in all respects and have different masses and chemical properties.
d. Atom is the smallest unit that takes part in chemical combinations.
d. Atoms of two or more elements combine in a simpler whole number ratio to form compound atoms (molecules).
e. Atoms can neither be created nor destroyed during any physical or chemical change.
f. Chemical reactions involve only combinations, separation or rearrangement of atoms.

Modern atomic theory
As a result of new discoveries made after Dalton developed his postulates, some modifications were done to atomic theory. They are:

1. Atom is no longer considered to be indivisible: It is found that atom is made up of subatomic particles such as electrons, protons and neutrons. We now state how many electrons are there, protons are there in an atom.

2. Atoms of same element may not be similar in all respects. Atoms of same elements have different atomic masses. These different atoms are called isotopes.

3. Atoms of different elements may have similar one or more properties. Atomic mass of calcium and argon (40 a.m.u.) are same. So the property of atomic mass is same for atoms of different elements. Isobars or elements or atoms having the same atomic mass.

4. Atom is the smallest unit which takes part in chemical reactions. Though electrons and protons are there, it is atom which takes part in chemical reactions and electrons exchange takes place between atoms.

5. The ratio in which the different atoms combine may be fixed and integral but may not always be simple. For example in sugar molecule the ratio of C,H and O atoms is 12:22:11, which is not simple.

6. Atom of one elements may be changed into atoms of other element. Transmutation is the process by which atoms one element can be changed inot elements of other elements by subjecting it to alpha rays.

7. The mass of atom can changed into energy. Mass and energy are inconvertible. The equation give for such conversion is E = mc². Hence we cannot say that mass is not destructible. But in chemical reactions, atom remains unchanged and its mass is not destroyed to liberate energy.

1.8 Avogadro's Hypothesis

Avogadro's hypothesis or suggestion is that matter consists of two kinds of ultimate particles. These are atoms and molecules.

Atoms are the smallest particle of an element which may or may not have independent existence, but it takes part in chemical reactions.

Molecule is the smallest particle of a substance (element or compound) capable of independent existence.

The actual hypothesis is that under similar conditions of temperature and pressure, equal volumes of all gases contain equal number of molecules.

1.9 Atoms and Molecules

Atoms are the smallest particle of an element which may or may not have independent existence, but it takes part in chemical reactions.

Molecule is the smallest particle of a substance (element or compound) capable of independent existence.

There are 112 elements in nature as per the present knowledge. Obviously there are 112 different types of atoms.

Molecules may have two or more atoms. Molecules are divided into two types:

1. Homoatomic molecules

2. Heteroatomic molecules

1.10 Atomic and Molecular Mass

Atomic Mass: An atom is such a small particle that its mass cannot be determined with the help of any available balance.  By an indirect method, the absolute mass of hydrogen atom has been found to be 1.66 X 10 to the power of -24 g.

Chemists have defined the atomic mass of hydrogen as one and expressed the atomic mass of other elements as multiples of hydrogen's atomic mass. The relative atomic masses expressed in terms of hydrogen as termed atomic weights.

Atomic weights of some common elements

Metals

Magnesium  24.3
Aluminium  27.0
Iron              55.8
Zinc             65.4
Tin             118.7

Gram Atomic Mass: Gram atomic mass is the quantity of an element whose mass in grams is numerically equal to its atomic mass.

Molecular Mass: Measuring the mass of a single molecule is not possible. Hence as in the case of atoms,  molecular mass is defined as the average relative mass of its molecule as compared to the mass of an atom of carbon (C12) having mass number 12.

11. Mole concept

A mole is measuring unit like for example dozen.
A mole is a collection of 6.022*10²³ particles

1.12 Mass-Mole Conversions

The mass of 6.022 X 10 to the power 23 molecules of a substance is equal to its gram moleculuar mass or gram molecule.

Ionic compound have the formula of composition of ions in the compound.  In their case the mass of one mole of formula units in grams is equal to  formula mass expressed in grams or gram formula mass of the compound. Thus, mass of 6.022 X 10 to the power 23 formula units (or one mole formula units) of any ionic substance in gram is equal to its gram formula mass.

Molar Mass: The mass of 1 mol of a substance is called its molar mass (M). The units of molar mass are g mol to the power -1 or kg mol to the power -1.

Mole in Terms of Volume

It has been observed that one mole (6.022 X 10 to the power 23 molecules) of an ideal gas occupies 22.4 litres at N.T.P. (0 degrees C and 1 atm pressure)

1.13 Percentage Composition and Molecular Formula

Molecular formula is also the chemical formula of a compound. It gives the representation of a molecule of a substance in terms of symbols of various elements present in it. The determiination of chemical formula requires chemical analysis to determine:

1. the elements present in it.
2. the relative of each element in the given mass of the compound.

Percentage Composition
The composition is generally expressed as the mass percentage composition. It gives the mass of each element expressed as the percentage of the total mass of the compound. It can also be expressed as the number of grams of the element present in 100 g of the compound.

Empirical Formula and Molecular Formula

Empirical formula gives the elements present in a compound.
Molecular formula gives the number of atoms of each element present in the compound. This is ascertained from the percentage composition calculations.

Stoichiometry

1.14 Stoichiometry of Chemical Equations
1.15 Stoichiometric Calculations
1.16 Limiting Reactant
1.17 Solution Stoichiometry
1.18 Stoichiometry of of Reactions in Solutions

1.14 Stoichiometry of Chemical Equations

Stoichiometry is derived from the Greek words stoicheion meaning elementand metron meaning measure.

It means measuring elements in chemical compounds. In chemical reactions, it is measuring reactants and products.

Stochiometric coefficients or numbers: The numbers which appear before the chemical symbols in a chemical equation.

Chemical equation gives information about moles of various reactants and products. Hence molar masses involved in the reaction and molar masses of products.

Balancing of Chemical Equations

1. Trial and error method
2. Partial equation method
3. Oxidation Number method
4. Ion-electron method

1.15 Stoichiometric Calculations

In stoichiometric calculations we find to mole to mole relationships in chemical equations. Mass to mass relationships are also calculated. Mass, volume relationships are calculated. Volume - volume relationships are calculated. You can imagine each of them based on the discussion we made above regarding mole concept, molecular mass, and mole volume.

1.16 Limiting Reactant

If reactants of different masses are mixed in a reaction vessel, the reactant that is completely consumed when a reaction goes to completion is called the limiting reactant of that mixture of reactants.  The other reactants present are called excess reagents. We need to minimize the excess reagents as it is a waste and we may not be able use them in other reactions due to their contamination in various ways because of using them in this reaction.

1.17 Solution Stoichiometry

In solution generally one component is present in lesser amount and it is called solute.

The other present in excess is called the solvent.

The amount of solute present in a given quantity of solvent or solution is expressed in terms of concentration.

Molarity = Amount of a substance (in mol)/Volume of solution expressed in dm^3
It is applicable to solutions only.

The unit of molarity is mol dm^-3. It is commonly abbreviated by the symbol M and is spelled as molar.

Molality = Amount of a a substance (in mol)/Mass of solvent expressed in kg
It is also applicable to solutions only

Mass percentage of substance in a system

Mole fraction of a substance in a system

CONCEPT OF EQUIVALENT
__________________________

"One equivalent of a substance in a reaction is defined as the amount of substance which reacts or liberates 1 mol of electrons (or H^+ or OH^- ions).

1.18 Stochiometry of reactions in solutions

Many reactions are carried out in aqueous solutions. In this case their concentration is important measure. The amounts of the products of a reaction can be calculated from the volumes of the solutions of the reactants and their concentrations. In the book, the calculations are illustrated through examples.



Contents of Chapter 1 of Jauhar

1.1 Importance of Studying Chemistry
1.2 Physical quantities and their S.I. Units
1.3 Dimensional Analysis
1.4 Measurement and Significant Figures
1.5 Chemical Classification of Matter
1.6 Laws of Chemical Combination
1.7 Dalton Atomic Theory
1.8 Avogadro's Hypothesis
1.9 Atoms and Molecules
1.10 Atomic and Molecular Mass
1.11 Mole Concept
1.12 Mass-Mole Conversions
1.13 Percentage Composition and Molecular Formula
1.14 Stoichiometry of Chemical Equations
1.15 Stoichiometric Calculations
1.16 Limiting Reactant
1.17 Solution Stoichiometry
1.18 Stoichiometry of of Reactions in Solutions


Updated  8 January 2020,  17 May, 16 May 2015

Last updated 19 Jan 2008, 30 Nov 2014