Syllabus of 12th CBSE Chemistry for Students

Syllabus of 12th CBSE Chemistry

Today we will discuss the Syllabus of Chemistry of the 12th standard of the CBSE board. What is Chemistry? What is the importance of Chemistry? Chemistry is a branch of science which deals with the study of matter its structure, composition, and its physical and chemical properties. We can hardly imagine our life without chemistry everything around us is chemistry food, toothpaste, perfume, medicine, and textile. Why we should study chemistry the simple answer to this question is to understand the world in a better way. Because the world is made up of matter and in chemistry, we study the matter.

At Higher Secondary lever Boys and girls are transformed from students to Scholars of a particular subject Hence the general curriculum is transformed into a disciplined centered curriculum. The syllabus of Chemistry is Developed by Expert Educationist of NCERT according to guidelines of National Education policy 2005. In this syllabus, more emphasis is given to comprehension and Understanding instead of the rote methods of learning. Students are made to understand the new things with the help of a diagram chart and concept map. This syllabus is prepared keeping in mind the Intellect and previous knowledge of students and the demand of the industry.

Now we will discuss the syllabus of chemistry in details. We will see what are the content of each unit and a brief introduction of each unit.

Syllabus of 12th CBSE Chemistry for Students

CBSE Class 12 Chemistry Syllabus 2020-21

Chemistry paper I (Inorganic and physical chemistry)

• Unit I Solid State
• Unit II Solutions
• Unit III Electrochemistry
• Unit IV Chemical Kinetics
• Unit V Surface Chemistry
• Unit VII p ‐Block Elements
• Unit VIII d ‐and f ‐Block Elements
• Unit IX Coordination Compounds

Chemistry paper-II (organic chemistry)

• Unit X Haloalkanes and Haloarenes
• Unit XI Alcohols, Phenols, and Ethers
• Unit XII Aldehydes, Ketones and Carboxylic Acids
• Unit XIII Amines
• Unit XIV Biomolecules
• Unit XV Polymers
• Unit XIV Chemistry in Everyday life

Chemistry paper I (Inorganic and Physical Chemistry)

Now we will see at a glance what is given in each unit.

• Unit 1 Solid State

In this lesson, we will study

• General characteristics of solid-state.
• what are amorphous and crystalline solids.
• classification of amorphous solid according to binding force.
• crystal lattice and unit cell.
• Packing of a particle in solid
• Explain voids and close-packed structures.
• Packing efficiency of different types of cubic unit cells
• Imperfections in solid and their effect on properties
• The relationship between the structure of solid and their electrical and magnetic properties.

Summary of lesson

There are three states of matter solid, liquid and gases. Solids have definite mass, volume and shape they are classified into amorphous and crystalline solid on the basis of range of order in the arrangement of their constituent particle.

Amorphous solids have a short range of order in the arrangement of particles and crystalline solid has a long range of order in the arrangement of particles. Crystalline solid is further classified into four different types Molecular, Ionic, metallic and covalent solids. This classification is based on the type of particle in solid and the type of bond between them.

The 3-dimensional array of points representing the position of particles of crystal in space is called lattice. In total 14 different types of lattice exist which are called Bravias lattices. Each lattice can be generated by repeating a small portion of lattice that small portion is called a unit cell. the unit cell is characterized by the length of an edge and three angles between the three edges. The unit cell has many types. For cubical crystal structure there are three types of unit cell 1) primitive cubic 2) body-centered cubic (BCC) 2) Face centered cubic (FCC).

Close packing in crystal refers to the space-efficient arrangement of particle. 74% space if filled in both hexagonal closed packed and face-centered cubic lattice. Other type of packing is not closed packing in body-centered cubic lattice 68% space is filled and in a simple cubic lattice, 52.4% space is filled.
solid are not perfect there are some defects in them these defects are called imperfections. There are two types of imperfection or defects point defect and line defect.

Semiconductor solids conductivity lies between that of insulator and conductor their electrical properties can be changed by adding impurities in them this process is called doping. Semiconductor devices are widely used in electrical devices. Solid also show different types of magnetic properties and All these properties can be correlated to their crystal structure and electronic configuration.

• Unit II Solutions

In this lesson, we will study

• formation of different type of solution
• Representation of concentration of the solution in different units.
• Henry’s law and Raoult’s law
• difference between ideal and non-ideal solution
• colligative properties of the solution and its relationship with molar masses and the solutes.
• Deviation of real solutions from Raoult’s law.
• Abnormal colligative properties shown by some solutes in solutions.

Summary of lesson

The homogeneous mixture of two or more substances is called a solution. The solutions are classified as solid, liquid, and gaseous solutions. The concentration of the solution is measured in terms of mole fraction, molarity, molality, and percentages.

Solubility of gas in a liquid is given by henry’s law. Which states that the “solubility of a gas in a liquid is directly proportional to the partial pressure of the gas at a given temperature of the gas. Raoult’s law gives us the relationship between the vapor pressure of solution and the mole fraction of the solvent according to it “vapor pressure in solution is equal to the vapor pressure of the pure solvent multiplied by its mole fraction in the solution.”The solution which obeys Raoult’s law over the entire range of concentration is called the ideal solution.

The colligative properties of the solution are those properties that depend upon the concentration of solute and not upon the chemical identity of solute examples of colligative properties are lowering of vapor pressure, boiling point elevation, freezing point depression, and osmotic pressure.

Colligative properties can be used to estimate the molar mass of the solute. The solute which dissociates in solution show molar mass less than the actual molar mass the solute which associates with the solution show molar mass more than the actual molar mass. The degree of dissociation or association of solute in a solvent is expressed in terms of van’t Hoff factor I .it is the ratio of observed colligative property to calculated colligative property.

• Unit III Electrochemistry

In this lesson, we will study

• what is an electrochemical cell what is the difference between galvanic and electrolytic cells.
• determination of emf of the galvanic cell by Nernst equation and define the standard potential of the cell.
• The mathematical relation between standard potential and Gibbs energy of cell reaction and its equilibrium constant.
• Definition of resistivity, conductivity, and molar conductivity of ionic solutions.
• difference between ionic and electronic conductivity.
• Estimation of conductivity of electrolytic solutions and calculation of their molar conductivity.
• Study of variation of conductivity and molar conductivity of solution with change in their concentration and define molar conductivity at zero concentration.
• Kohlraush law and its application.
• Quantitative aspects of electrolysis and construction of primary and secondary batteries and fuel cells.
• Describe corrosion as an electrochemical process.

Summary of the lesson

Two metallic electrodes deeped in electrolytic solution forms an electrochemical cell.

Thus an important component of the electrochemical cell is an electrolyte. Electrochemical cells are of two types galvanic cells and electrolytic cells. In the galvanic cell, the chemical energy of spontaneous redox reaction is converted into electrical energy, while in an electrolytic cell, electrical energy is used to carry out non-spontaneous redox reaction.

The standard electrode potential of the cell is different of the standard potentials of cathode and anode(Ecell =Ecathode – Eanode). The standard potential of the cells is related to standard Gibbs energy and equilibrium constant.

Conductivity decrease with a decrease in the concentration of electrolyte and molar conductivity increase with the increase in the concentration of electrolyte. Kohlrausch determines the conductivity at infinite dilution. The law states that limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte. It is known as the law of independent migration of ions and has many applications. Ions conduct electricity through the solution but oxidation and reduction of the ions take place at the electrodes in an electrochemical cell. Batteries and fuel cells are very useful types of galvanic cells. Corrosion of metals is an electrochemical process. Electrochemical principles are relevant to the Hydrogen Economy.

• Unit IV Chemical kinetics

In this lesson, we will study

• Define the average and instantaneous rate of a reaction.
• Relation between the rate of reaction in terms of change in concentration of either the reactant or product with time.
• Difference between elementary and complex reactions
• Difference between the molecularity and order of a reaction.
• What is rate constant
• How the rate of reaction depends on concentration, temperature, and catalyst;
• Derivation of Integrated rate equations for the zero and first-order reactions
• Determine the rate constants for a zeroth and first-order reactions.
• Explanation of Collision theory

Summary of the lesson

Chemical kinetics is a branch of chemistry which deals with the study of the rate of reaction or speed of reaction. The rate of reaction depends on the number of factors such as temperature, the concentration of reactant, and catalyst. Rate law mathematically represents the rate of reaction. The rate of reaction depends on the concentration of the reactant. The power of concentration of reactant is called the order of reaction. Arrhenius equation gives the relationship between temperature and rates constant. (k = Ae–Ea/RT).

Ea corresponds to the activation energy and is given by the energy difference between the activated complex and the reactant molecules, and A (Arrhenius factor or pre-exponential factor) corresponds to the collision frequency. The equation indicates that a rise of temperature or lowering of Ea will lead to a rise in the rate of reaction and the presence of a catalyst decreases the activation energy by giving an alternate path for the reaction.

According to collision theory, another factor P called steric factor which refers to the orientation of molecules that collide, is important and contributes to effective collisions thus, modifying the Arrhenius equation to a /AB Z e E RT k = P − .

Unit V Surface Chemistry

In this lesson, we will study

• Explanation and importance of the interfacial phenomenon.
• Explanation of adsorption and its classification as physical and chemical adsorption.
• Mechanism of adsorption;
• Explanation of the factors affecting adsorption from gases and
• solutions on solids;
• Explanation of Freundlich adsorption isotherms;
• Appreciate the role of catalysts in industry;
• Explanation of the nature of colloidal state;
• Explanation preparation, properties and purification of colloids;
• classify emulsions and explain their preparation and properties;
• illustration of the phenomenon of gel formation;
• uses of colloids.

Summary of this Unit

The process of attracting and retaining the molecules of substance on the surface of solid which results into a higher concentration on the surface than in the bulk is called adsorption. The substance adsorbed is known as adsorbate and the substance on which adsorption takes place is called adsorbent. In physical adsorption, adsorbate is held to the adsorbent by weak van der Waals forces, and in chemical adsorption, adsorbate is held to the adsorbent by a strong chemical bond.

Almost all solids adsorb gases. The degree of adsorption of a gas on a solid depends upon the nature of gas, the nature of the solid, surface area of the solid, pressure of the gas, and temperature of the gas. The relationship between the extent of adsorption (x/m) and the pressure of the gas at constant temperature is known as adsorption isotherm.

A catalyst is a substance which enhances the rate of a chemical reaction without itself getting used up in the reaction. The phenomenon using a catalyst is known as catalysis. In homogeneous catalysis, the catalyst is in the same phase as are the reactants, and in heterogeneous catalysis, the catalyst is in a different phase from that of the reactants. Colloidal solutions are intermediate between true solutions and suspensions.

The size of the colloidal particles ranges from 1 to 1000 nm. A colloidal system consists of two phases – the dispersed phase and the dispersion medium.

Colloidal systems depending upon (i) physical states of the dispersed phase and dispersion medium (ii) nature of interaction between the dispersed phase and dispersion medium and (iii) nature of particles of dispersed phase. The colloidal systems show interesting optical, mechanical and electrical properties. The process of changing the colloidal particles in a sol into the insoluble precipitated by the addition of some suitable electrolytes is known as coagulation. Emulsions are colloidal systems in which both dispersed phase and dispersion medium are liquids. These can be of: (i) oil in water type and (ii) water in oil type. The process of making emulsion is known as emulsification. To stabilise an emulsion, an emulsifying agent or emulsifier is added. Soaps and detergents are most widely used as emulsifiers. Colloids find many applications in industry as well as in daily.

NOTE: Unit VI has deleted from the syllabus, therefore, we will not discuss it here.

• Unit VII P-Block Element

In this lesson, we will study

• Study of general trends in the chemistry of elements of groups 15,16,17 and 18;
• learn the preparation, properties, and uses of dinitrogen and phosphorus and some of their important compounds;
• the preparation, properties, and uses of dioxygen and ozone and chemistry of some simple oxides;
• Study of allotropic forms of sulphur, the chemistry of its important compounds, and the structures of its oxoacids;
• The preparation, properties, and uses of chlorine and hydrochloric acid;
• know the chemistry of interhalogens and structures of oxoacids of halogens;
• the uses of noble gases;
• The importance of these elements and their compounds in our day-to-day life.

Summary of the Unit

The p-block Element lies between groups 13 to 18. The valence electron of the p-block Element lies in any of the three p-orbitals of the respective shell. Group 13 and 14 are already discussed in class XI now we will discuss groups 14 to 18 in Class XII.

Group 15 contains five elements N, P, As, Sb, and Bi Which have general electronic configuration ns2np3. Elements of group 15 show trends in properties. They react with oxygen, hydrogen, and halogens. They show two important oxidation states, + 3 and + 5 but +3 oxidation is favoured by heavier elements due to the ‘inert pair effect’.

Dinitrogen can be made in laboratory as well as on industrial scale. It forms oxides in different oxidation states as N2O, NO, N2O3, NO2, N2O4 and N2O5. These oxides have resonating structures and have multiple bonds. Herber’s process is used to make ammonia on large scale. HNO3 is a useful industrial chemical. It is a strong monobasic acid and is a powerful oxidizing agent. Metals and non-metals react with HNO3 under different conditions to give NO or NO2. Phosphorus exists as P4 in elemental form. It exists in several allotropic forms.

It forms hydride, PH3 which is a highly toxic gas. It forms two types of halides as PX3 and PX5. PCl3 is synthesised by the reaction of white phosphorus with dry chlorine while PCl5 is made by the reaction of phosphorus with SO2Cl2. Phosphorus forms a number of oxoacids. Depending upon the number of P–OH groups, their basicity varies. The oxoacids which have P–H bonds are good reducing agents.

• Unit VIII d and f Block Element

In this lesson, we will study

• location of the d and f block elements in the periodic table.
• Electronic configuration of d-block and f-block elements.
• Stability of various oxidation states in terms of electrode potential values.
• preparation,properties,structures and uses of potassium dichromate and potassium permanganate.
• The general trends in properties of d and f block elements.

Summary of the unit

The d-block consist of groups 3 to 12 in periodic table. There is three series of d-block element 3d,4d and 5d series of a transition element. All the transition elements exhibit typical metallic properties.Ionisation Enthaples do on rise as steeply as in the main group elements with rise in atomic number. Potassium dichromate and potassium permanganate are perfect examples of oxametallic slats formed from transition metals both of them are good oxidizing agents.The f-block elements are present at the bottom of the periodic table. They are divided into two groups lanthanoids and actinoids

• Unit IX Coordination Compound

In this lesson we will study

• Assumptions of Werner’s Theory of coordination compound.
• defination of the terms: coordination entity,central atom/ion,ligand,coordination number,coordination sphere,coordination polyhedron,oxidation number,homoleptic and heteroleptic.
• Nomenclature of coordination compounds.
• Types of isomerism in coordination compounds
• Valence Bond and Crsytal Field theories and it’s relationship with nature of bonding in coordination compounds
• Stability of coordiantion compound.
• Importance and application of coordination compound in day-to-day life.

Summary of the unit

The chemistry of coordination compounds is very important. In the last fifty years, progress in this area, have provided development of new concepts and models of bonding and molecular structure, novel breakthroughs in chemical industry and vital insights into the functioning of critical components of biological systems. A Warner was the first person to explain formation,structure and reactions of coordinate compound. His theory postulated the use of two types of linkages (primary and secondary) by a metal atom/ion in a coordination compound.

In the modern language of chemistry these linkages are recognised as the ionizable (ionic) and non-ionisable (covalent) bonds, respectively. Using the property of isomerism, Werner predicted the geometrical shapes of a large number of coordination compounds.

The Valence Bond Theory (VBT) explains the formation, magnetic behaviour and geometrical shapes of coordination compounds. It, however, fails to provide a quantitative interpretation of magnetic behavior and has nothing to say about the optical properties of these compounds.

The Crystal Field Theory (CFT) to coordination compounds is based on the effect of different crystal fields (provided by the ligands taken as point charges), on the degeneracy of d orbital energies of the central metal atom/ion.

The splitting of the d orbitals provides different electronic arrangements in strong and weak crystal fields. The treatment provides for quantitative estimations of orbital separation energies, magnetic moments, and spectral and stability parameters.

However, the assumption that ligands consititute point charges create many theoretical difficulties. The metal–carbon bond in metal carbonyls possesses both σ and π character. The ligand to metal is σ bond and metal to ligand is π bond. This unique synergic bonding provides stability to metal carbonyls. The stability of coordination compounds is measured in terms of stepwise stability (or formation) constant (K) or overall stability constant (β).

The stabilization of the coordination compound due to chelation is called the chelate effect. The stability of coordination compounds is related to Gibbs energy, enthalpy and entropy terms. Coordination compounds are of great importance. These compounds provide critical insights into the functioning and structures of vital components of biological systems. Coordination compounds also find extensive applications in metallurgical processes, analytical and medicinal chemistry.

Chemistry paper-II (Organic Chemistry)

• Unit X Haloalkanes and Haloarenes

What you will study in this unit.

• The IUPAC name of haloalkanes and haloarenes.
• Preparation of haloalkanes and haloarenes and reactions involving them.
• Relation of structures of haloalkanes and haloarenes with various types of reaction.
• Understanding mechanism of reactions in terms of Stereochemistry.
• Application of organometallic compounds.
• Environmental effects of polyhalogen compounds.

Summary of the unit.

Alky/Aryl halides are classified according to the presence of one, two, or more halogen atoms in their formula as mono, di, or polyhalogen compounds. Because halogen atoms are more electronegative than carbon atoms the carbon-halogen bond of alkyl halide is polarised. The carbon atom carries a partial positive charge and the halogen atom carries a partial negative charge.

Alkyl halides are formed due to radical halogenation of alkanes, the addition of halogen acids to alkenes, replacement of -OH group of alcohols with halogens using phosphorus halides, thionyl chloride, or halogen acids. Aryl halides are formed by electrophilic substitution to arenes.

The boiling point of the organohalogen compounds are higher than the corresponding hydrocarbons because of strong dipole-dipole and van der Waals forces of attraction. Organohalogen compounds are slightly soluble in water but completely soluble in organic solvents.

The polarity of the carbon-halogen bond of alky halides plays an important role in nucleophilic substitution, elimination, and their reactions with metal atoms to form organometallic compounds. On the basis of kinetic properties, the nucleophilic substitution reaction are divided into types SN1 and SN2 reactions. SN1 is characterized by racemization. SN2 is characterized by the inversion of configuration.

The polyhalogen compounds such as dichloromethane, chloroform, iodoform, carbon tetrachloride, freon, and DDT have many industrial applications. But some of these compounds cannot decompose easily and cause depletion of the ozone layer.

• Unit XI Alcohols, Phenols, and Ethers

In this unit, you will study

• IUPAC names of alcohols, phenols, and ethers.
• Preparation of alcohols from i)alkenes ii) aldehydes, ketones, and carboxylic acids.
• Preparation of phenols from i) haloarenes ii) benzene sulphonic acids iii) diazonium salts and iv Cumene.
• Preparation of Ethers from I) Alcohols and ii) Alky halides and sodium alkoxides/aryloxides.
• Interrelation between the structures and physical properties of alcohols, phenols, and ethers.
• Chemical Reactions of Alcohols, Phenols, and Ethers.

Summary of the unit

Alcohols are classified depending upon the number of the hydroxy groups attached into monohydric alcohols, dihydric alcohols, and trihydric alcohols. Alcohols are also classified depending on the hybridization of the carbon atom, sp3 or sp2 to which the -OH group is attached into primary alcohols, secondary alcohols, and Tertiary alcohols. Ethers are classified on the basis of the group attach to the oxygen atom.

Alcohols can be synthesized by following reactions

1) By hydration of alkenes.

• In presence of an acid.
• By hydroboration-oxidation reaction.

2) From carbonyl compounds by

• catalytic reduction.
• the Action of Grignard reagents.

Phenols may be prepared by 1) Substitution of I) Halogen atom in haloarenes and II) Sulphonic acid group in aryl sulphonic acids by -OH group 2) By hydrolysis of diazonium salts and 3) Industrially from cumene.

Alcohols have a high boiling point. Alcohols, phenols, and others are soluble in water because of their ability to form intermolecular hydrogen bonding with water.

Alcohols and phenols are acidic in nature. Alkyl halides are formed from alcohols in nucleophilic substitution reactions. alkenes are formed by the dehydration of alcohols. Oxidation of primary alcohols gives aldehydes and carboxylic acid and Oxidation of secondary alcohols gives ketones.

The presence of the –OH group in phenols activates the aromatic ring towards electrophilic substitution and directs the incoming group to ortho and para positions due to the resonance effect. Reimer-Tiemann reaction of phenol yields salicylaldehyde. In presence of sodium hydroxide, phenol generates phenoxide ion which is even more reactive than phenol.

Thus, in an alkaline medium, phenol undergoes Kolbe’s reaction. Ethers may be prepared by (i) dehydration of alcohols and (ii) Williamson synthesis. The boiling points of ethers resemble those of alkanes while their solubility is comparable to those of alcohols having the same molecular mass. The C–O bond in ethers can be cleaved by hydrogen halides. In electrophilic substitution, the alkoxy group activates the aromatic ring and directs the incoming group to ortho and para positions.

• Unit XII Aldehydes, Ketones and Carboxylic Acids

In this lesson, we will study

• IUPAC name of aldehydes, ketones, and carboxylic acids.
• Structures of the compounds containing functional groups namely carbonyl and carboxyl groups.
• Method of preparation and reaction of Aldehydes, Ketones, and Carboxylic Acids.
• Physical and chemical properties of aldehydes, ketones, and carboxylic acids and its relation with their structures.
• Mechanism of some reactions of Aldehydes and Ketones.
• Factors affecting the acidity of carboxylic acids and their reactions.
• Uses of aldehydes, ketones, and carboxylic acids.

Summary of the lessons

Aldehydes, Ketones, and Carboxylic acids are highly polar molecules hence they boil at higher temperatures. The lower members are more soluble in water and the higher members are insoluble in water but soluble in organic solvents. Aldehydes are prepared by dehydrogenation or controlled oxidation of primary alcohols and controlled or selective reduction of acyl halides.

Aromatic aldehydes can be synthesized by oxidation of I) methylbenzene with chromyl chloride or CrO3 in the presence of acetic anhydride ii) formylation of arenes with carbon monoxide and hydrochloric acid in the presence of anhydrous aluminum chloride, and iii) cuprous chloride or by hydrolysis of benzal chloride.

Ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Ketones are also synthesized by the reaction of an acyl chloride with dialkycadmium. Aromatic ketones are synthesized by Friedel-Crafts acylation reaction.OZonolysis of alkenes produces both aldehydes and ketones. Aldehydes and ketones undergo nucleophilic addition reactions onto the carbonyl group with a number of nucleophiles such as HCN, NaHSO3, alcohols (or diols), ammonia derivatives, and Grignard reagents.

The α-hydrogens in aldehydes and ketones are acidic. Therefore, aldehydes and ketones having at least one α-hydrogen, undergo Aldol condensation in the presence of a base to give α-hydroxyaldehydes (aldol) and α-hydroxyketones(ketol), respectively. Aldehydes having no α-hydrogen undergo Cannizzaro reaction in the presence of concentrated alkali. Aldehydes and ketones are reduced to alcohols with NaBH4, LiAlH4, or by catalytic hydrogenation. The carbonyl group of aldehydes and ketones can be reduced to a methylene group by Clemmensen reduction or Wolff-Kishner reduction.

Aldehydes are easily oxidized to carboxylic acids by mild oxidizing reagents such as Tollens’ reagent and Fehling’s reagent. These oxidation reactions are used to distinguish aldehydes from ketones. Carboxylic acids are prepared by the oxidation of primary alcohols, aldehydes, and alkenes by hydrolysis of nitriles, and by treatment of Grignard reagents with carbon dioxide.

Aromatic carboxylic acids are also prepared by side-chain oxidation of alkylbenzenes. Carboxylic acids are considerably more acidic than alcohols and most of the simple phenols. Carboxylic acids are reduced to primary alcohols with LiAlH4, or better with diborane in ether solution and also undergo α-halogenation with Cl2 and Br2 in the presence of red phosphorus (Hell-Volhard Zelinsky reaction). Methanal, ethanal, propanone, benzaldehyde, formic acid, acetic acid, and benzoic acid are highly useful compounds in industry.

• Unit XIII Amines

In this unit you will study.

• Study of amines as derivatives of ammonia having a pyramidal structure.
• Classification amines as primary,secondary, and tertiary
• Common and IUPAC names of Amines.
• Methods of preparation of amines
• Properties of amines.
• Preparation of Diazonium salts and their role in synthesis of series of aromatic compounds including azo dyes.

Summary of the lesson

Amines are obtained from ammonia by the replacement of hydrogen atoms with alkyl or aryl groups. Amines are classified as a primary, secondary, and tertiary amine.
Secondary and tertiary amines are known as simple amines if the alkyl or aryl group are the same and mixed amines if the group are different. All amines are basic in nature because they have one lone pair of electrons.

Amines are usually formed from nitro compounds, halides, amides, imides, etc. They exhibit hydrogen bonding which influences their physical properties. In alkylamines, a combination of electron releasing, steric and H-bonding factors influence the stability of the substituted ammonium cations in protic polar solvents and thus affect the basic nature of amines. Alkylamines are found to be stronger bases than ammonia.

In aromatic amines, electron releasing and withdrawing groups, respectively increase and decrease their basic character. Aniline is a weaker base than ammonia. Reactions of amines are governed by the availability of the unshared pair of electrons on nitrogen. The influence of the number of hydrogen atoms at nitrogen atom on the type of reactions and nature of products is responsible for the identification and distinction between primary, secondary, and tertiary amines.

p-Toluenesulphonyl chloride is used for the identification of primary, secondary, and tertiary amines. The presence of amino groups in aromatic rings enhances the reactivity of the aromatic amines. Reactivity of aromatic amines can be controlled by the acylation process, i.e., by treating with acetyl chloride or acetic anhydride. Tertiary amines like trimethylamine are used as insect attractants.

Aryldiazonium salts, usually obtained from arylamines, undergo replacement of the diazonium group with a variety of nucleophiles to provide advantageous methods for producing aryl halides, cyanides, phenols, and arenes by reductive removal of the diazo group. The coupling reaction of aryldiazonium salts with phenols or arylamines gives rise to the formation of azo dyes.

• Unit XIV Biomolecules

In this Unit, you will study.

• Characteristics of biomolecules like carbohydrates, proteins, and nucleic acids, and hormones.
• Classification of carbohydrates, proteins, nucleic acids, and vitamins on the basis of their structures.
• Difference between DNA and RNA.
• Role Biomolecules in biosystem.

Summary of the lesson

Carbohydrates are optically active polyhydroxy aldehydes or ketones or molecules which provide such units on hydrolysis. They are broadly classified into three groups — monosaccharides, disaccharides, and polysaccharides.

Glucose, the most important source of energy for mammals, is obtained by the digestion of starch. Monosaccharides are held together by glycosidic linkages to form disaccharides or polysaccharides.

Proteins are the polymers of about twenty different α-amino acids which are linked by peptide bonds. Ten amino acids are called essential amino acids because they cannot be synthesized by our body, hence must be provided through diet. Proteins perform various structural and dynamic functions in organisms. Proteins which contain only α-amino acids are called simple proteins.

The secondary or tertiary structure of proteins get disturbed on change of pH or temperature and they are not able to perform their functions. This is called the denaturation of proteins. Enzymes are biocatalysts that speed up the reactions in biosystems. They are very specific and selective in their action and chemically all enzymes are proteins.

Vitamins are accessory food factors required in the diet. They are classified as fat-soluble (A, D, E, and K) and water-soluble (Β group and C). The deficiency of vitamins leads to many diseases.

Nucleic acids are the polymers of nucleotides which in turn consist of a base, a pentose sugar, and phosphate moiety. Nucleic acids are responsible for the transfer of characters from parents to offsprings. There are two types of nucleic acids — DNA and RNA. DNA contains a five-carbon sugar molecule called 2-deoxyribose whereas RNA contains ribose. Both DNA and RNA contain adenine, guanine, and cytosine. The fourth base is thymine in DNA and uracil in RNA.

The structure of DNA is a double strand whereas RNA is a single strand molecule. DNA is the chemical basis of heredity and has the coded message for proteins to be synthesized in the cell. There are three types of RNA — mRNA, rRNA, and tRNA which actually carry out the protein synthesis in the cell.

• Unit XV Polymers

In this Unit, we will study.

• Definition of monomer, polymer, and polymerization and its importance.
• Difference between different types of polymers and different types of the polymerization process.
• The formation of polymers from mono and bifunctional monomer molecules.
• Preparation of some important synthetic polymers and their properties.
• Significance of polymer.

Summary of the unit

Polymers are defined as high molecular mass macromolecules, which consist of repeating structural units derived from the corresponding monomers. These polymers may be of natural or synthetic origin and are classified in a number of ways.

In the presence of an organic peroxide initiator, the alkenes and their derivatives undergo additional polymerization or chain growth polymerization through a free radical mechanism. Polythene, Teflon, orlon, etc. are formed by the addition polymerization of an appropriate alkene or its derivative. Condensation polymerization reactions are shown by the interaction of bi – or polyfunctional monomers containing – NH2, – OH, and – COOH groups.

This type of polymerization proceeds through the elimination of certain simple molecules as H2O, CH3OH, etc. Formaldehyde reacts with phenol and melamine to form the corresponding condensation polymer products. The condensation polymerisation progresses through step by step and is also called as step-growth polymerization.

Nylon, bakelite, and dacron are some of the important examples of condensation polymers. However, a mixture of two unsaturated monomers exhibits copolymerization and forms a co-polymer containing multiple units of each monomer. Natural rubber is a cis 1, 4-polyisoprene and can be made tougher by the process of vulcanization with sulfur.

Synthetic rubbers are usually obtained by copolymerization of alkene and 1, 3 butadiene derivatives. In view of the potential environmental hazards of synthetic polymeric wastes, certain biodegradable polymers such as PHBV and Nylon-2- Nylon-6 are developed as alternatives.

• Unit XIV Chemistry in Everyday life

In this Unit, you will study

• Importance of chemistry in daily life.
• Describe the term Chemotherapy.
• Classification of drugs.
• Describe drug-target interaction of enzymes and receptors.
• Describe how various types of drugs function in the body.
• Artificial sweetening agents and food preservatives
• Chemistry of cleaning agents

Summary of the lesson

Chemistry is essentially the study of materials and the development of new materials for the betterment of humanity. A drug is a chemical agent, which affects human metabolism and provides a cure from the ailment. If taken in doses higher than recommended, these may have a poisonous effect.

The use of chemicals for therapeutic effect is called chemotherapy. Drugs usually interact with biological macromolecules such as carbohydrates, proteins, lipids and nucleic acids. These are called target molecules.

Drugs are designed to interact with specific targets so that these have the least chance of affecting other targets. This minimizes the side effects and localizes the action of the drug. Drug chemistry centers around arresting microbes/destroying microbes, preventing the body from various infectious diseases, releasing mental stress, etc. Thus, drugs like analgesics, antibiotics, antiseptics, disinfectants, antacids and tranquilizers are used for specific purpose.

To check the population explosion, antifertility drugs have also become prominent in our life. Food additives such as preservatives, sweetening agents, flavors, antioxidants, edible colors, and nutritional supplements are added to the food to make it attractive, palatable, and add nutritive value. Preservatives are added to the food to prevent spoilage due to microbial growth. Artificial sweeteners are used by those who need to check their calorie intake or are diabetic and want to avoid taking sucrose.

These days, detergents are much in vogue and get preference over soaps because they work even in hard water. Synthetic detergents are classified into three main categories, namely: anionic, cationic, and non-ionic, and each category has its specific uses. Detergents with a straight chain of hydrocarbons are preferred over the branched chains as the latter are non-biodegradable and consequently cause environmental pollution.

Conclusion: The syllabus is designed to prepare students for professional courses of the Medical, Engineering, and Pharmacy fields. This syllabus equips the student with the necessary theoretical and practical knowledge of chemistry which is very useful in the field of applied sciences.

FAQ