Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Organic Chemistry – Reagents, Field Effects, Stability, Bond Cleavage

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What Is Organic Chemistry?

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

The term  ‘organic’ was coined because the field of organic chemistry was initially finite to compounds that were produced by living organisms. This was attributed to some ‘vital force’ that was present in organic substances as they had something that inanimate substances lacked. The above theory was debunked when Urey Miller synthesised urea from inorganic substances, but the classification is still in use.

Organic chemistry is a vast science due to one key property exhibited by the element carbon, which is called carbon catenation. Carbon has the exceptional ability to form very stable bonds with other carbon atoms, giving it the ability to form stable molecules with relatively complex structures. Catenation is the ability of an element to form bonds with an atom of the same kind. Hence, the vastness of organic chemistry can be attributed to this property of carbon.

The importance of organic chemistry in the present age is as immense as it has been since its inception. It plays an important role in our everyday life because food, medicines, paper, clothes, soap, perfumes, etc., are indispensable to us for proper living. The study of organic chemistry is important for chemists and pharmacists in synthesising medicines for the alleviation of human suffering.

The reactions in organic chemistry occur between organic compounds. Let us now study the different terminologies, classifications, field effects, types of reagents, the stability of intermediates, and properties in detail.

Cleavage of Bonds

The reactions in organic chemistry occur through the breaking and making of bonds. Bonds can cleave in either of two ways:

  • Homolytic cleavage
  • Heterolytic cleavage

What Is Homolytic Cleavage?

If the covalent bonds between two elements break in such a way that each of the elements gets its own electrons, it is called homolytic cleavage. That is, each element gets an electron. Homolytic cleavage results in the formation of free radicals.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Homolytic Cleavage of Covalent Bond

In the above figure, we have used an arrow to show the movement of electrons. Here, in this case, the arrow used is called the fish-hook arrow, as it signifies that there is a movement of only one electron.

What Is Heterolytic Cleavage?

If the covalent bonds between two elements break heterolytically, i.e., unequally, it results in the formation of charged species. This type of bond breaking, where the electrons are unevenly distributed, is called heterolytic cleavage.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Heterolytic Cleavage of Covalent Bond

In the above figure, we have used arrows to signify the movement of electrons, a regular arrow signifies that two electrons are being moved.

Reaction Intermediates in Organic Chemistry

Intermediates can be understood as the first product of a consecutive reaction. For example, in a chemical reaction, if A→B and B→C, then B can be said to be the intermediate for reaction A→C. The reactions in organic chemistry occur via the formation of these intermediates.

What Are Carbenes?

Carbenes (H2C) are neutral and reactive species that have six electrons in the outer shell of carbon, making them electron deficient. Since carbenes are species having two odd electrons, we can classify carbenes based on their spin states.

Singlet Carbene

The electrons are present in different orbitals with opposite spins. The electrons are paired in sp2 hybridized orbitals and behave as paired electrons.

Spin state= (2S + 1), S for singlet carbene is zero, as the electrons are antiparallel.

Therefore, spin state = (2 × 0 + 1) = 1

Triplet Carbene

Both electrons are present in different orbitals, and they possess the same spin.

Spin state = (2S + 1), S for triplet carbene is 1, as both electrons have the same spin.

Therefore, spin state= (2 × 1 + 1) = 3

Hybridization of Singlet and Triplet Carbene

Singlet carbene hybridization: They are sp2 hybridized with a bent shape. They have a bond angle of 103° and a bond length of 112 pm.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Hybridization of Singlet Carbene

Triplet carbene hybridization: They possess a sp hybrid orbital with a linear shape. They have a bond angle and bond length of 180° and 103 pm, respectively.

Why Is Triplet Carbene More Stable than Singlet?

Triplet carbene has lower energy than singlet carbene because, in singlet carbene, there are more inter-electronic repulsions as both the electrons exist in the same orbital, whereas in triplet carbene, the two electrons exist in different orbitals, making it possess less energy.

What Are Free Radicals?

Free radicals in organic chemistry are formed by the homolytic cleavage of carbon bonds. The shape of the species formed is planar, and the carbon is sp3 hybridized with an odd electron being placed in the p-orbital. If the free radical is relatively stable, then it may possess a planar structure.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Planar Structure of Free Radicals

Carbanions and Carbocations

What Are Carbanions?

They are generated by heterolytically cleaving a group attached to carbon without removing the bonded electrons. This makes the carbon have a pair of electrons, thereby imparting a negative charge on the carbon. CH3– is isoelectronic with NH3, and it is sp3 hybridized, and the shape is pyramidal owing to the presence of a lone pair of electrons.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Formation of Carbanions and Carbocations

What Are Carbocations?

Carbocations have a sextet of electrons on the carbon-containing positive charge and are hence termed ‘cations’. It is sp2 hybridized and has an empty p-orbital. The shape is planar. It is generally formed by heterolytic cleavage of a carbon-heteroatom bond.

Transition State in Organic Reactions

We saw the intermediates that could be formed in an organic reaction; now, let us look into transition states and the difference between an intermediate and a transition state.

The intermediates in organic chemistry are formed in a multi-step reaction, but some reactions can occur in a single step without having to form an intermediate. These reactions will occur by going through a transition state. This can be clear by looking at the energy profile diagram for a reaction, R→P.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

The transition state corresponds to the highest energy in the reaction, after which it can give either the products or, in the case of a reversible reaction, the reactants.

Consider a reaction, A→D with the following steps, A→B, B→C, and C→D

The energy profile for this reaction is given below:

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

We can see that B and C are the products of a reaction, and hence they are termed intermediates. The highest energy of a particular reaction should be the transition state.

Conclusion:

From the above example, we can show that the intermediates are isolable, that is, they can be isolated. On the other hand, the transition state is not isolable because we assume the reaction to take place via a transition state cannot be isolated.

Reagents in Organic Chemistry

Reagents are the chemicals that we add to bring about a specific change to an organic molecule. Any general reaction in organic chemistry can be written as follows:

Substrate + Reagent → Product

Where the substrate is an organic molecule to which we add the reagent. Based on the ability to either donate or abstract electrons, the reagents can be classified as follows:

  • Electrophiles
  • Nucleophiles

Electrophiles

Electrophiles are electron-deficient organic reagents. It can be generalised that all the positive charge-containing species are electrophiles. For example, H+, NO2+, CH3+, Cl+ 

Check: Electrophilic Substitution Reaction

Neutral molecules that are electron deficient can also act as electrophiles. Lewis acids like AlCl3 and BF3 are examples of neutral electrophiles.

Nucleophiles

Nucleophiles are electron-rich organic reagents. They seek bonding centres with other nuclei and hence the name nucleophile. It can be generalised that negative charge-containing species are nucleophiles. For example, H–, CH3–, and Cl–.

Neutral molecules with a lone pair of electrons on the heteroatom can act as a nucleophile. For example, H2O, NH3, and CH3OH.

Types of Reactions in Organic Chemistry

Organic reactions are reactions that occur between organic compounds. The reactions in organic chemistry are broadly classified into six categories. Let us study in detail these different types of reactions and their products.

Substitution Reactions

R-X + Y → R-Y +X

Where R-X is the substrate, Y is the reagent (which can be electrophilic or nucleophilic), and X is called the leaving group. The term substitution means one group is replacing the other group.

Types of Substitution Reaction:

  1. Nucleophilic Substitution ( SN1, SN2, SNi)
  2. Electrophilic Substitution (SE)
  3. Nucleophilic Aromatic Substitution (SNAr)
  4. Addition Reactions

Addition reactions can be further classified into:

  1. Electrophilic Addition
  2. Nucleophilic Addition
  3. Elimination Reactions

Elimination Reactions

These reactions can be said to be the reverse of an addition reaction, wherein a simple molecule (HX, H2O) is removed from the substrate, i.e., a molecule is said to be eliminated from the substrate. Elimination reaction can be classified further into E1, E2, and E1CB.

  1. Oxidation and reduction reactions
  2. Pericyclic reactions
  3. Molecular rearrangements

Field Effect in Organic Chemistry

Inductive Effect

It is an electron delocalisation effect via σ bonds that arises due to the difference in electronegativities. For example, in a σ bonded organic compound like C-C-C-Cl, the carbon attached to the chlorine atom can be referred to as the α-carbon, and the one adjacent to that carbon as the ß-carbon and so on.

Now, since chlorine is more electronegative than carbon, it withdraws the electrons that are present via the σ bond toward itself, thereby making Cα fractionally positive. Since it is devoid of electrons, Cα, now being slightly electropositive than Cß, pulls the sigma-bonded electrons of Cα-Cß bond toward itself, and in this process, it makes Cß slightly electropositive.

The electron-withdrawing effect of the chlorine atom is transmitted through the carbon chain via the σ bonds. This transmission of charges decreases rapidly with the number of intervening σ bonds. We can practically ignore this effect beyond Cß.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

The arrow is pointed more towards the electronegative atom. If a group withdraws the electron from carbon, it makes carbon slightly electropositive. Such groups are called -I groups, and the effect is termed -I effect. For example, -Cl, -Br, -CN and -NO2 are -I groups.

Groups that release electrons towards carbon are termed +I groups, and the effect is termed as +I inductive effect in organic chemistry. For example, alkyl groups like -CH3 are +I groups.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Electromeric Effect

It is the temporary delocalisation of π-electrons in a compound containing multiple covalent bonds. It is important to note that it is only a temporary effect, that is, it occurs only when a reagent is added. The Electromagnetic Effect in organic chemistry can be classified into two types:

  • Positive Electromeric Effect
  • Negative Electromeric Effect

Positive Electromeric Effect

When the π-electrons are given to the attacking reagent, for example, the reactions alkenes and alkynes mostly occur via +E, this reaction is also called electrophilic addition.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Positive Electromeric Effect

The proton adds at C-1 as the π-electrons were given to the attacking reagent (H+). This results in the formation of a carbocation.

Negative Electromeric Effect

When the π-electrons are shifted to a more electronegative atom (O, N, S) joined via multiple bonds, it is called the negative electromeric effect. For example, the reactions of aldehydes and ketones occur predominantly by the -E effect. It is also called nucleophilic addition.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Negative Electromeric Effect

The CN- ion adds to the C atom of the carboxy group opposite to the movement of the π-electron cloud.

Mesomeric Effect

Molecules possessing sigma bonds and pi-bonds alternatively exhibit the mesomeric effect. The effect is exhibited due to the permanent delocalisation of π-bonds. This increases the number of resonating structures which makes the molecules of organic chemistry more stable. Such kind of a system, where there are alternative sigma and pie bonds, is called conjugated.

Types of Mesomeric Effect

  • Positive mesomeric effect
  • Negative mesomeric effect:

Positive Mesomeric Effect

This effect is exhibited when the direction of the delocalisation of electrons is away from the position where the group is attached. Normally, groups having a lone pair of electrons attached to a conjugated system push electrons into the conjugated system, that is, away from them.

Groups in organic chemistry showing positive mesomeric effect (+M) effect are -OH, -OR, -NH2, -SH, -X, etc.

Negative Mesomeric Effect

This effect is exhibited when the direction of the delocalisation of electrons is towards the position where the group is attached. These are generally electron-withdrawing groups of organic chemistry.

Resonance Effect

For certain molecules like carbonate ion (CO32-), one single Lewis structure would not be enough to explain all of the properties. In that case, the molecule is said to have more than one structure.

Each of those structures can explain some of the properties but not all of the properties. The actual structure of the molecule is a hybrid of all the possible structures (canonical forms). This phenomenon is called resonance in organic chemistry. If resonance occurs, each bond would be both a single bond and a double bond at the same time, i.e. the bond order would lie between one and two.

Resonating structures should fulfil the following criteria:

  1. All atoms should have the same positions in all the structures.
  2. There should have the same number of paired and unpaired electrons.
  3. The structures should have almost the same energies.

Note: Canonical forms do not have any existence in reality.

Resonance Energy

The energy difference between the most stable canonical form and the resonance hybrid is known as Resonance Energy. The more the resonance energy, the more the stability.

Rules for finding out the most stable canonical form:

  1. The canonical form with no charges is the most stable
  2. The canonical form with more number of covalent bonds is more stable
  3. The canonical form where unlike charges are in close proximity are more stable
  4. If they are to be charged, the negative charge should be on an electronegative atom. Then, this canonical form is said to be more stable.

Role of Steric Hindrance

The structure and reactivity of many compounds in organic chemistry are greatly dictated by the presence of bulky groups or constituents in the molecule. This is called steric hindrance. It arises because of inter-electronic repulsions due to spatial crowding amongst bulky groups. Using steric factors, we can conclude that trans-2-butene is more stable than cis-2-butene.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Steric Hindrance in Organic Chemistry

Stability of Intermediates

Carbocations

The stability of carbocations can be explained by the Inductive Effect.

CH3++CH2(CH3) +CH(CH3)2+C(CH3)3, i.e., Methyl Primary (1°) Secondary (2°) Tertiary(3°)

We know that alkyl groups of organic chemistry are +I groups, that is, they release electrons through the sigma bonds.

Since the carbon is deficient in electrons, we can say that as the number of methyl groups increases, the stability of the carbocation increases, as the electropositive carbon is satiated by the electrons given by the methyl groups via the +I effect.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Therefore, the stability order of carbocations in organic chemistry is of the order 3° > 2° > 1° > Methyl carbocation.

Hyperconjugation

When a C-H σ-bond is in conjugation with a carbocation, this effect is observed. A carbocation has a vacant p-orbital. The bonded σ-electron pair of the C-H bond is displaced towards the vacant p-atomic orbital. This increases the electron density in the empty p-AO.

It is, therefore, a resonance effect, where a C-H bond breaks and the σ-electron pair is delocalised to the vacant p-AO of the carbonation. Since the bond between C and H is broken, it is also called ‘no bond resonance’. It is also referred to as the Baker-Nathan effect.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

The more the number of α-hydrogens in a carbonation, the more hyperconjugated structures would be possible. The more the number of structures, the more the stability of the species.

Stability of Carbanions

The stability of carbanions can be explained using the inductive effect.

CH3 — CH2(CH3) — CH(CH3)2 — C(CH3)3 i.e. Methyl Primary (1°) Secondary (2°) Tertiary (3°)

Since alkyl groups are electron-releasing by nature through induction, we can say that the more the number of methyl groups attached to the carbon having a negative charge, the less its stability would be.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

This is because the carbon already has a negative charge, to which the methyl groups push electrons via induction. This results in inter-electronic repulsions and destabilises the species.

Therefore, the stability order for carbanions is as follows:

3°< 2°< 1°< Methyl carbanion

Stability of Free Radicals

The stability of free radicals in organic chemistry follows the same trend as that of carbocations.

CH3–CH2(CH3)–CH(CH3)2–C(CH3)3 i.e. Methyl Primary (1°) — Secondary (2°) — Tertiary(3°)

Therefore, the stability order of free radicals is of order: 3° > 2° > 1° > methyl carbocation.

This can be explained with the help of the Hyperconjugation that we saw, but there would be an overlap between the σ-bond of C-H and the odd electron in the p-orbital of carbon.

Organic chemistry is the branch of Chemistry that involves the scientific study of organic compounds (compounds that contain covalently bonded carbon atoms). This branch of chemistry primarily deals with the structure and chemical composition of organic compounds, the physical and chemical properties of organic compounds, and the chemical reactions undergone by these compounds. Advancements in the field of organic chemistry have made numerous contributions to human society, such as the synthesis of several drugs, polymers, and other natural products. Synthetic organic chemistry is an important application of organic chemistry that deals with the design and construction of organic compounds for practical purposes.

Note: If there is a possibility of resonance, then that would make it more stable. This is because resonance affects the entire structure.

Frequently Asked Questions

1. What is the meaning of bond cleavage?

Answer:

The breaking of a chemical bond is called bond cleavage. There are two types of bond cleavage depending on the sharing of electrons between the two atoms of the bond.

1. Homolytic cleavage: The two electrons in the bond are equally shared between the two atoms.

2. Heterolytic cleavage: One of the atoms gets both the electrons of the bond.

2. What makes a strong nucleophile?

Answer: 

The conjugate base of a good nucleophile. For example, OH– is a good nucleophile than H2O. The greater the negative charge, the atoms are more likely to give electrons to form a bond.

3. Is water (H2O) nucleophile or electrophile?

Answer:

Water is a highly polar compound with a high density of electrons or electron-rich molecules. Hence, water is an example of a nucleophile.

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

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CBSE Class 11 Chemistry Syllabus

CBSE Class 11 Chemistry Syllabus is a vast which needs a clear understanding of the concepts and topics. Knowing CBSE Class 11 Chemistry syllabus helps students to understand the course structure of Chemistry.

Unit-wise CBSE Class 11 Syllabus for Chemistry

Below is a list of detailed information on each unit for Class 11 Students.

UNIT I – Some Basic Concepts of Chemistry

General Introduction: Importance and scope of Chemistry.

Nature of matter, laws of chemical combination, Dalton’s atomic theory: concept of elements,
atoms and molecules.

Atomic and molecular masses, mole concept and molar mass, percentage composition, empirical and molecular formula, chemical reactions, stoichiometry and calculations based on stoichiometry.

UNIT II – Structure of Atom

Discovery of Electron, Proton and Neutron, atomic number, isotopes and isobars. Thomson’s model and its limitations. Rutherford’s model and its limitations, Bohr’s model and its limitations, concept of shells and subshells, dual nature of matter and light, de Broglie’s relationship, Heisenberg uncertainty principle, concept of orbitals, quantum numbers, shapes of s, p and d orbitals, rules for filling electrons in orbitals – Aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of atoms, stability of half-filled and completely filled orbitals.

UNIT III – Classification of Elements and Periodicity in Properties

Significance of classification, brief history of the development of periodic table, modern periodic law and the present form of periodic table, periodic trends in properties of elements -atomic radii, ionic radii, inert gas radii, Ionization enthalpy, electron gain enthalpy, electronegativity, valency. Nomenclature of elements with atomic number greater than 100.

UNIT IV – Chemical Bonding and Molecular Structure

Valence electrons, ionic bond, covalent bond, bond parameters, Lewis structure, polar character of covalent bond, covalent character of ionic bond, valence bond theory, resonance, geometry of covalent molecules, VSEPR theory, concept of hybridization, involving s, p and d orbitals and shapes of some simple molecules, molecular orbital theory of homonuclear diatomic molecules(qualitative idea only), Hydrogen bond.

UNIT V – Chemical Thermodynamics

Concepts of System and types of systems, surroundings, work, heat, energy, extensive and intensive properties, state functions. First law of thermodynamics – internal energy and enthalpy, measurement of U and H, Hess’s law of constant heat summation, enthalpy of bond dissociation, combustion, formation, atomization, sublimation, phase transition, ionization, solution and dilution. Second law of Thermodynamics (brief introduction)
Introduction of entropy as a state function, Gibb’s energy change for spontaneous and nonspontaneous processes.
Third law of thermodynamics (brief introduction).

UNIT VI – Equilibrium

Equilibrium in physical and chemical processes, dynamic nature of equilibrium, law of mass action, equilibrium constant, factors affecting equilibrium – Le Chatelier’s principle, ionic equilibrium- ionization of acids and bases, strong and weak electrolytes, degree of ionization,
ionization of poly basic acids, acid strength, concept of pH, hydrolysis of salts (elementary idea), buffer solution, Henderson Equation, solubility product, common ion effect (with illustrative examples).

UNIT VII – Redox Reactions

Concept of oxidation and reduction, redox reactions, oxidation number, balancing redox reactions, in terms of loss and gain of electrons and change in oxidation number, applications of redox reactions.

UNIT VIII – Organic Chemistry: Some basic Principles and Techniques

General introduction, classification and IUPAC nomenclature of organic compounds. Electronic displacements in a covalent bond: inductive effect, electromeric effect, resonance and hyper conjugation. Homolytic and heterolytic fission of a covalent bond: free radicals, carbocations, carbanions, electrophiles and nucleophiles, types of organic reactions.

UNIT IX – Hydrocarbons

Classification of Hydrocarbons
Aliphatic Hydrocarbons:
Alkanes – Nomenclature, isomerism, conformation (ethane only), physical properties, chemical reactions.
Alkenes – Nomenclature, structure of double bond (ethene), geometrical isomerism, physical properties, methods of preparation, chemical reactions: addition of hydrogen, halogen, water, hydrogen halides (Markovnikov’s addition and peroxide effect), ozonolysis, oxidation, mechanism of electrophilic addition.
Alkynes – Nomenclature, structure of triple bond (ethyne), physical properties, methods of preparation, chemical reactions: acidic character of alkynes, addition reaction of – hydrogen, halogens, hydrogen halides and water.

Aromatic Hydrocarbons:

Introduction, IUPAC nomenclature, benzene: resonance, aromaticity, chemical properties: mechanism of electrophilic substitution. Nitration, sulphonation, halogenation, Friedel Craft’s alkylation and acylation, directive influence of functional group in monosubstituted benzene. Carcinogenicity and toxicity.

To know the CBSE Syllabus for all the classes from 1 to 12, visit the Syllabus page of CBSE. Meanwhile, to get the Practical Syllabus of Class 11 Chemistry, read on to find out more about the syllabus and related information in this page.

CBSE Class 11 Chemistry Practical Syllabus with Marking Scheme

In Chemistry subject, practical also plays a vital role in improving their academic scores in the subject. The overall weightage of Chemistry practical mentioned in the CBSE Class 11 Chemistry syllabus is 30 marks. So, students must try their best to score well in practicals along with theory. It will help in increasing their overall academic score.

CBSE Class 11 Chemistry Practical Syllabus

The experiments will be conducted under the supervision of subject teacher. CBSE Chemistry Practicals is for 30 marks. This contribute to the overall practical marks for the subject.

The table below consists of evaluation scheme of practical exams.

Evaluation SchemeMarks
Volumetric Analysis08
Salt Analysis08
Content Based Experiment06
Project Work04
Class record and viva04
Total30

CBSE Syllabus for Class 11 Chemistry Practical

Micro-chemical methods are available for several of the practical experiments. Wherever possible such techniques should be used.

A. Basic Laboratory Techniques
1. Cutting glass tube and glass rod
2. Bending a glass tube
3. Drawing out a glass jet
4. Boring a cork

B. Characterization and Purification of Chemical Substances
1. Determination of melting point of an organic compound.
2. Determination of boiling point of an organic compound.
3. Crystallization of impure sample of any one of the following: Alum, Copper Sulphate, Benzoic Acid.

C. Experiments based on pH

1. Any one of the following experiments:

  • Determination of pH of some solutions obtained from fruit juices, solution of known and varied concentrations of acids, bases and salts using pH paper or universal indicator.
  • Comparing the pH of solutions of strong and weak acids of same concentration.
  • Study the pH change in the titration of a strong base using universal indicator.

2. Study the pH change by common-ion in case of weak acids and weak bases.

D. Chemical Equilibrium
One of the following experiments:

1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing the concentration of either of the ions.
2. Study the shift in equilibrium between [Co(H2O)6] 2+ and chloride ions by changing the concentration of either of the ions.

E. Quantitative Estimation
i. Using a mechanical balance/electronic balance.
ii. Preparation of standard solution of Oxalic acid.
iii. Determination of strength of a given solution of Sodium hydroxide by titrating it against standard solution of Oxalic acid.
iv. Preparation of standard solution of Sodium carbonate.
v. Determination of strength of a given solution of hydrochloric acid by titrating it against standard Sodium Carbonatesolution.

F. Qualitative Analysis
1) Determination of one anion and one cation in a given salt
Cations‐ Pb2+, Cu2+, As3+, Al3+, Fe3+, Mn2+, Ni2+, Zn2+, Co2+, Ca2+, Sr2+, Ba2+, Mg2+, NH4 +
Anions – (CO3)2‐ , S2‐, NO2‐ , SO32‐, SO2‐ , NO ‐ , Cl‐ , Br‐, I‐, PO43‐ , C2O2‐ ,CH3COO‐
(Note: Insoluble salts excluded)

2) Detection of ‐ Nitrogen, Sulphur, Chlorine in organic compounds.

G) PROJECTS
Scientific investigations involving laboratory testing and collecting information from other sources.

A few suggested projects are as follows:

  • Checking the bacterial contamination in drinking water by testing sulphide ion
  • Study of the methods of purification of water.
  • Testing the hardness, presence of Iron, Fluoride, Chloride, etc., depending upon the regional
    variation in drinking water and study of causes of presence of these ions above permissible
    limit (if any).
  • Investigation of the foaming capacity of different washing soaps and the effect of addition of
    Sodium carbonate on it.
  • Study the acidity of different samples of tea leaves.
  • Determination of the rate of evaporation of different liquids Study the effect of acids and
    bases on the tensile strength of fibres.
  • Study of acidity of fruit and vegetable juices.

Note: Any other investigatory project, which involves about 10 periods of work, can be chosen with the approval of the teacher.

Practical Examination for Visually Impaired Students of Class 11

Below is a list of practicals for the visually impaired students.

A. List of apparatus for identification for assessment in practicals (All experiments)
Beaker, tripod stand, wire gauze, glass rod, funnel, filter paper, Bunsen burner, test tube, test tube stand,
dropper, test tube holder, ignition tube, china dish, tongs, standard flask, pipette, burette, conical flask, clamp
stand, dropper, wash bottle
• Odour detection in qualitative analysis
• Procedure/Setup of the apparatus

B. List of Experiments A. Characterization and Purification of Chemical Substances
1. Crystallization of an impure sample of any one of the following: copper sulphate, benzoic acid
B. Experiments based on pH
1. Determination of pH of some solutions obtained from fruit juices, solutions of known and varied
concentrations of acids, bases and salts using pH paper
2. Comparing the pH of solutions of strong and weak acids of same concentration.

C. Chemical Equilibrium
1. Study the shift in equilibrium between ferric ions and thiocyanate ions by increasing/decreasing
the concentration of eitherions.
2. Study the shift in equilibrium between [Co(H2O)6]2+ and chloride ions by changing the
concentration of either of the ions.

D. Quantitative estimation
1. Preparation of standard solution of oxalic acid.
2. Determination of molarity of a given solution of sodium hydroxide by titrating it against standard
solution of oxalic acid.

E. Qualitative Analysis
1. Determination of one anion and one cation in a given salt
2. Cations – NH+4
Anions – (CO3)2-, S2-, (SO3)2-, Cl-, CH3COO-
(Note: insoluble salts excluded)
3. Detection of Nitrogen in the given organic compound.
4. Detection of Halogen in the given organic compound.

Note: The above practicals may be carried out in an experiential manner rather than recording observations.

We hope students must have found this information on CBSE Syllabus useful for their studying Chemistry. Learn Maths & Science in interactive and fun loving ways with ANAND CLASSES (A School Of Competitions) App/Tablet.

Frequently Asked Questions on CBSE Class 11 Chemistry Syllabus

Q1

How many units are in the CBSE Class 11 Chemistry Syllabus?

There are 9 units in the CBSE Class 11 Chemistry Syllabus. Students can access various study materials for the chapters mentioned in this article for free at ANAND CLASSES (A School Of Competitions).

Q2

What is the total marks for practicals examination as per the CBSE Class 11 Chemistry Syllabus?

The total marks for the practicals as per the CBSE Class 11 Chemistry Syllabus is 30. It includes volumetric analysis, content-based experiment, salt analysis, class record, project work and viva.

Q3

Which chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry?

The organic chemistry chapter carries more weightage as per the CBSE Syllabus for Class 11 Chemistry.

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