Hybridization, in Chemistry, is defined as the concept of mixing two atomic orbitals to give rise to a new type of hybridized orbitals. This intermixing usually results in the formation of hybrid orbitals having entirely different energy, shapes, etc.

The atomic orbitals of the same energy level mainly take part in hybridization. However, both fully-filled and half-filled orbitals can also take part in this process, provided they have equal energy.

On the other hand, we can say that the concept of hybridization is an extension of the valence bond theory, and it helps us to understand the formation of bonds, bond energies and bond lengths.

Table of Contents

What Is Hybridization?

Redistribution of the energy of orbitals of individual atoms to give orbitals of equivalent energy happens when two atomic orbitals combine to form a hybrid orbital in a molecule. This process is called hybridization. 

During the process of hybridization, the atomic orbitals of comparable energies are mixed together and mostly involves the merging of two ‘s’ orbitals or two ‘p’ orbitals or the mixing of an ‘s’ orbital with a ‘p’ orbital, as well as ‘s’ orbital with a ‘d’ orbital. The new orbitals, thus formed, are known as hybrid orbitals. 

More significantly, hybrid orbitals are quite useful in explaining atomic bonding properties and molecular geometry.

Let us have a quick look at the example of a carbon atom. This atom forms 4 single bonds wherein the valence-shell s orbital mixes with 3 valence-shell p orbitals. This combination leads to the formation of 4 equivalent sp³ mixtures. They will have a tetrahedral arrangement around the carbon, which is bonded to 4 different atoms.

Key Features of Hybridization

• Atomic orbitals with equal energies undergo hybridization.
• The number of hybrid orbitals formed is equal to the number of atomic orbitals mixed.
• It is not necessary that all the half-filled orbitals must participate in hybridization. Even completely filled orbitals with slightly different energies can also participate.
• Hybridization happens only during the bond formation and not in an isolated gaseous atom.
• The shape of the molecule can be predicted if the hybridization of the molecule is known.
• The bigger lobe of the hybrid orbital always has a positive sign, while the smaller lobe on the opposite side has a negative sign.

Try this: Give the hybridization states of each of the carbon atoms in the given molecule.

• H₂C = CH – CN
• HC ≡ C − C ≡ CH
• H₂C = C = C = CH₂

Types of Hybridization

Based on the types of orbitals involved in mixing, the hybridization can be classified as sp³, sp², sp, sp³d, sp³d² and sp³d³. Let us now discuss the various types of hybridization, along with their examples.

sp Hybridization

sp hybridization is observed when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals. The new orbitals formed are called sp hybridized orbitals. It forms linear molecules with an angle of 180°.

• This type of hybridization involves the mixing of one ‘s’ orbital and one ‘p’ orbital of equal energy to give a new hybrid orbital known as an sp hybridized orbital.
• The sp hybridization is also called diagonal hybridization.
• Each sp hybridized orbital has an equal amount of s and p characters – 50% s and 50% p characters.

Examples of sp Hybridization:

• All compounds of beryllium, like BeF₂, BeH_2, BeCl₂
• All compounds of a carbon-containing triple bond, like C₂H₂.

sp² Hybridization

sp² hybridization is observed when one s and two p orbitals of the same shell of an atom mix to form 3 equivalent orbitals. The new orbitals formed are called sp² hybrid orbitals. 

• sp² hybridization is also called trigonal hybridization.
• It involves the mixing of one ‘s’ orbital and two ‘p’ orbitals of equal energy to give a new hybrid orbital known as sp².
• A mixture of s and p orbital formed in trigonal symmetry and is maintained at 120⁰.
• All three hybrid orbitals remain in one plane and make an angle of 120° with one another. Each of the hybrid orbitals formed has a 33.33% ‘s’ character and 66.66% ‘p’ character.
• The molecules in which the central atom is linked to 3 atoms and is sp2 hybridized have a triangular planar shape.

Examples of sp² Hybridization

• All the compounds of Boron, i.e., BF_{3 and} BH₃
• All the compounds of carbon, containing a carbon-carbon double bond, Ethylene (C₂H₄)

sp³ Hybridization

When one ‘s’ orbital and 3 ‘p’ orbitals belonging to the same shell of an atom mix together to form four new equivalent orbitals, the type of hybridization is called a tetrahedral hybridization or sp³. The new orbitals formed are called sp³ hybrid orbitals.

• These are directed towards the four corners of a regular tetrahedron and make an angle of 109°28’ with one another.
• The angle between the sp3 hybrid orbitals is 109.28⁰
• Each sp³ hybrid orbital has 25% s character and 75% p character.
• Examples of sp³ hybridization are ethane (C₂H₆) and methane.

sp³d Hybridization

sp³d hybridization involves the mixing of 1s orbital, 3p orbitals and 1d orbital to form 5 sp³d hybridized orbitals of equal energy. They have trigonal bipyramidal geometry.

• The mixture of s, p and d orbital forms trigonal bipyramidal symmetry.
• Three hybrid orbitals lie in the horizontal plane inclined at an angle of 120° to each other, known as the equatorial orbitals.
• The remaining two orbitals lie in the vertical plane at 90 degrees plane of the equatorial orbitals, known as axial orbitals.
• Example: Hybridization in phosphorus pentachloride (PCl₅)

sp³d² Hybridization

• sp³d² hybridization has 1s, 3p and 2d orbitals, that undergo intermixing to form 6 identical sp³d² hybrid orbitals.
• These 6 orbitals are directed towards the corners of an octahedron.
• They are inclined at an angle of 90 degrees to one another.

Frequently Asked Questions on Hybridization

Q1

What are the different types of hybridization?

Based on the nature of the mixing orbitals, hybridization can be classified in the following ways:

• sp hybridization (beryllium chloride, acetylene)
• sp² hybridization (boron trichloride, ethylene)
• sp³ hybridization (methane, ethane)
• sp³d hybridization (phosphorus pentachloride)
• sp³d² hybridization (sulphur hexafluoride)
• sp³d³ hybridization (iodine heptafluoride)

⇒ Know more about VSEPR theory, its postulates and limitations

Q2

Among sp, sp² and sp³, which hybrid orbital is more electronegative?

The percentage of s character in sp, sp² and sp³ hybridized carbon is 50%, 33.33%, and 25%, respectively.

⇒ Also Read:

Due to the spherical shape of the s orbital, it is attracted evenly by the nucleus from all directions. Therefore, a hybrid orbital with more s-character will be closer to the nucleus, and thus more electronegative. Hence, the sp hybridized carbon is more electronegative than sp² and sp³.

Q3

Why is the hybrid orbital during hybridization better than its parent atoms?

The reason why a hybrid orbital is better than its parents is as follows:

• Parent s: because it is directional, unlike the s orbital.
• Parent p: because it has lower energy than p orbital.

Q4

What are hybrid orbitals?

Hybrid orbitals can be defined as the combination of standard atomic orbitals resulting in the formation of new atomic orbitals.

⇒ Check: Fajan’s Rule and Its Postulates

During hybridization, the hybrid orbitals possess different geometry of orbital arrangement and energies than the standard atomic orbitals. Also, the orbital overlap minimises the energy of the molecule. The degenerate hybrid orbitals formed from the standard atomic orbitals are as listed:

• 1s and 1 p: sp orbitals
• 1s and 2p: sp² orbitals
• 1s and 3p: sp³ orbitals
• 1s, 3p, and 1d: sp³d orbitals
• 1s, 3p, and 2d: sp³d² orbitals

Q5

What is the difference between sp, sp² and sp³ hybridization?

The sp hybridization occurs due to the mixing of one s and one p atomic orbital, the sp² hybridization is the mixing of one s and two p atomic orbitals, and the sp³ hybridization is the mixing of one s and three p atomic orbitals.

Q6

What is the percentage of s and p characters in sp, sp² and sp³ hybrid orbitals?

The percentage of s and p characters in sp, sp² and sp³ hybrid orbitals is,

Sp: s characteristic 50% and p characteristic 50%

Sp²: s characteristic 33.33% and p characteristic 66.66%

Sp³: s characteristic 25% and p characteristic 75%

Q7

Explain the five basic shapes of hybridization.

The five basic shapes of hybridization are linear, trigonal planar, tetrahedral, trigonal bipyramidal and octahedral.

The geometry of the orbital arrangement is as follows:

• Linear: Two electron groups are involved resulting in sp hybridization; the angle between the orbitals is 180°.
• Trigonal planar: Three electron groups are involved resulting in sp² hybridization, and the angle between the orbitals is 120°.
• Tetrahedral: Four electron groups are involved resulting in sp³ hybridization, and the angle between the orbitals is 109.5°.
• Trigonal bipyramidal: Five electron groups are involved resulting in sp³d hybridization; the angle between the orbitals is 90°, 120°.
• Octahedral: Six electron groups are involved resulting in sp³d² hybridization, and the angle between the orbitals is 90°.

Q8

Explain the sp3 hybridization in methane.

The 2s and all the three (3p) orbitals of carbon hybridize to form four sp³ orbitals. These hybrid orbitals bond with four atoms of hydrogen through sp3-s orbital overlap resulting in CH₄ (methane). The geometry of orbital arrangement due to the minimum electron repulsion is tetrahedral.

Q9

The amide molecule looks like the sp³ hybridized, but it is sp². Why?

The general process of hybridization will change if the atom is either enclosed by two or more p orbitals or it has a lone pair to jump into a p orbital. Therefore, in the case of an amide molecule, the lone pair goes into a p orbital to have 3 adjacent parallel p orbitals (conjugation).

Q10

What results in the sp, sp² and sp³ hybridization?

The sp and sp² hybridization results in two and one unhybridized p orbitals, respectively, whereas in the sp3 hybridization, there are no unhybridized p orbitals.

Q11

Explain the difference between molecular and hybrid orbitals.

The interactions between the atomic orbitals of two different atoms result in molecular orbitals, whereas when the atomic orbitals of the same atom interact, they form hybrid orbitals.

Neeraj Anand, Param Anand

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.

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‐ , S^2‐, NO₂^‐ , SO₃^2‐, SO^2‐ , NO ^‐ , Cl^‐ , Br^‐, I‐, PO₄^3‐ , 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.