Hydrogen is the most abundant element or chemical substance that is available in our universe. It makes up 90 per cent of all the atoms. It is the smallest and the lightest of all elements having atomic number 1 and an atomic weight of 1.008. Hydrogen is found mostly in the form of a gas and is colourless, odourless but flammable.

Hydrogen-Methods of Preparation, Isotopes, Types, Properties

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Hydrogen is the most abundant element or chemical substance that is available in our universe. It makes up 90 per cent of all the atoms. It is the smallest and the lightest of all elements having atomic number 1 and an atomic weight of 1.008. Hydrogen is found mostly in the form of a gas and is colourless, odourless but flammable.

Hydrogen, even though it is present in large quantities, is rarely found in its naturally free state. It is mostly found in chemical compounds where it is bonded to other elements. The most common example that we can take is water, where hydrogen is bonded with the oxygen molecule. Interestingly, when hydrogen is burned, it usually reacts with oxygen in the atmosphere to form water. This is also the primary reason why it was named “hydrogen”, derived from the Greek word “hydro genes”, meaning water creator/former.

Position of Hydrogen in Periodic Table

Hydrogen resembles I A group alkali metals and VII-A group halogens. It is for this reason that it is placed on top of the periodic table.

The Resemblance with I A Group (Alkali Metals)

1. Both the alkali metals and hydrogen have one electron in their valence shell.

Explanation:

H (Z = 1)  – K1

Li (Z = 3) – K2, L1

Na (Z = 11) – K2, L8, M1

K (Z = 19) – K2, L8, M8, N1 

2. Hydrogen and elements of I A group shows the same outer configuration ns1

Explanation:

H (Z = 1) – 1s1

Li (Z = 3) – 1s2, 2s1

Na (Z = 11) – 1s2, 2s2, 2p6, 3s1

K (Z = 19) – 1s2, 2s2, 2p6, 3s2, 3p6, 4s1

3. Hydrogen also forms halides like alkali metals.

Explanation:

I-A: NaCl, KBr.

Hydrogen: HCl, HI.

4. During electrolysis, hydrogen gas is liberated at the cathode.

5. Oxidation state of alkali metals and hydrogen is +1.

6. Halides of hydrogen undergo ionisation in an aqueous solution, similar to alkali metal halids.

Explanation:

HCl(aq)→ H+(aq) + Cl–(aq)

NaCl(aq)→ Na+(aq) + Cl–(aq)

7. Hydrogen may also form non-metal compounds, such as alkali metals.

Explanation:

Hydrogen: H2S

I-A: Na2S

The Resemblance of Hydrogen with Halogens

1. Both hydrogen and halogen are non-metals. (Iodine is excluded because of its partial metallic character.)

2. Hydrogen has a higher electronegativity (2.1).

3. It has high ionisation potential.

4. It accepts one electron easily and forms a hydride ion (H–) like a halide ion (X–).

5. Both hydrogen and halogen forms compound with metals and non-metals.

Explanation: 

Halogen: HCl (H is non-metal)

Hydrogen: H2S ( S is non-metal)

Thus, hydrogen resembles more with halogen than alkali metals. Hence, the position of hydrogen is not justified in the periodic table.

Differences between Alkali Metals and Halogens

  • It is less electropositive than alkali metals and less electronegative than halogens.
  • It contains only one proton (but no neutrons) in its nucleus and only one electron in the extranuclear part.
  • It forms a neutral oxide.
  • The sizes of H and H ions are much smaller than those of alkali metals.
  • The hydrogen ion (H+) is unstable in water, unlike Na+ and K+ ions.

Properties of Hydrogen

Physical Properties of Hydrogen

  1. Colourless, odourless and neutral gas
  2. Less soluble in water
  3. Highly inflammable
  4. Burns with a blue flame
  5. Very low boiling points

Chemical Properties of Hydrogen

  1. Dihydrogen is relatively inert at room temperature because of the strong bond enthalpy of the H–H bond.
  2. Atomic hydrogen is produced under a high electric arc.
  3. Its orbit is incomplete with a single electron.
  4. Hydrogen combines with almost every element.

Isotopes of Hydrogen

Hydrogen shows three isotopes, and they are

  1. \(\begin{array}{l}\text{Protium}\ \left( _{1}^{1}H \right):\ \text{It has zero neutrons}.\end{array} \)
  2. \(\begin{array}{l}\text{Deuterium}\ \left( _{1}^{2}H \right):\ \text{It has one neutrons}.\end{array} \)
  3. \(\begin{array}{l}\text{Tritium}\ \left( _{1}^{3}H \right):\ \text{It has two neutrons.}\end{array} \)

Allotropes of Hydrogen

Molecular hydrogen occurs in two isomeric forms.

  1. Ortho-hydrogen: In this type, two proton nuclear spins are aligned parallel.
  2. Para-hydrogen: In this type, two proton nuclear spins are aligned antiparallel.

Different Forms of Hydrogen

Atomic Hydrogen:

It is produced when molecular hydrogen is passed through an electric arc (2273k) struck between tungsten electrodes. The reaction is endothermic, and the heat is stored in the atoms.

H2→ 2H- Heat 

(Heat at 2273 K in an electric arc)

The liberated hydrogen atoms recombine to form H, with the evolution of a large amount of energy which can be used for welding purposes.

Nascent Hydrogen:

It is the hydrogen at the moment of its generation, i.e., when it is just liberated. Nascent hydrogen is much more reactive and is a much more powerful reducing agent than ordinary hydrogen.

Reason for the activity of nascent hydrogen

  • Atomic state (the atom is more reactive than molecules).
  • Chemical energy is liberated during the reaction.
  • High internal pressure due to nascent hydrogen atoms.

Methods of Preparation of Hydrogen

By the Electrolysis of Water

\(\begin{array}{l}2{{H}_{2}}0\xrightarrow{\text{electric current}}2{{H}_{2}}\left( g \right)+{{O}_{2}}\left( g \right)\end{array} \)

By the Action of Acids on Strong Electro Positive Metals

\(\begin{array}{l}2Na+{{H}_{2}}S{{O}_{4}}\rightarrow{{}}N{{a}_{2}}S{{O}_{4}}+{{H}_{2}}\end{array} \)

\(\begin{array}{l}2K+2HCl\rightarrow{{}}2KCl+{{H}_{2}}\end{array} \)

By the Action of Water on Strong Electro Positive Metals

\(\begin{array}{l}2Na+2{{H}_{2}}O\rightarrow{{}}2NaOH+{{H}_{2}}\end{array} \)

By the Action of Alkali on Amphoteric Metals Like Al, Zn, etc.

\(\begin{array}{l}\underset{\left(Hot\,\And\,Concentrated\right)}{\mathop{6NaOH}}\,+2Al\rightarrow{{}}\underset{Sod.\,Aluminate}{\mathop{2N{{a}_{3}}Al{{o}_{3}}}}\,+3{{H}_{2}}\end{array} \)

\(\begin{array}{l}Zn+2NaOH\rightarrow{{}}\underset{Sod.\,Zincate}{\mathop{N{{a}_{2}}Zn{{O}_{2}}}}\,+{{H}_{2}}\end{array} \)

Large Scale Production of Hydrogen

\(\begin{array}{l}C{{H}_{4}}+{{H}_{2}}O\rightarrow[100-1000{}^\circ C]{3-25\,bar}10+2{{H}_{2}}\end{array} \)

\(\begin{array}{l}CO+{{H}_{2}}O\rightarrow{{}}C{{O}_{2}}+{{H}_{2}}\end{array} \)

Also Read: Preparation Method and Use of Hydrogen

Chemical Reactions of Hydrogen

With Oxygen

It reacts with dioxygen to form water. The reaction is highly exothermic.

\(\begin{array}{l}{{H}_{2}}+\frac{1}{2}{{O}_{2}}\xrightarrow[\Delta ]{200^\circ C}{{H}_{2}}O\end{array} \)

With Metals

With many metals, hydrogen reacts and combines at a high temperature to yield a corresponding hydride.

\(\begin{array}{l}2Na+{{H}_{2}}\xrightarrow[\Delta ]{350^\circ C}\underset{Sodium\,hydride}{\mathop{2NaH}}\,\end{array} \)

With Halogens

It reacts with halogens to give hydrogen halides.

\(\begin{array}{l}{{H}_{2}}+{{F}_{2}}\xrightarrow{dark}2HF\end{array} \)

\(\begin{array}{l}{{H}_{2}}+C{{l}_{2}}\xrightarrow{sun\,\,light}2HCl\end{array} \)

\(\begin{array}{l}{{H}_{2}}+B{{r}_{2}}\xrightarrow{350{}^\circ C}2HBr\end{array} \)

\(\begin{array}{l}{{H}_{2}}+{{I}_{2}}\longrightarrow 2HI\end{array} \)

With Dinitrogen

With dinitrogen, it forms ammonia at 73k and 200 atm pressure.

3H2(g) + N2(g) → 2NH3                                              ∆H = -92.6 kJ mol

This is the method for the manufacture of ammonia by the Haber process.

Reducing Action

\(\begin{array}{l}W{{O}_{3}}+3{{H}_{2}}\rightarrow{{}}3{{H}_{2}}O+W\end{array} \)

Nuclear Fusion Reactions

It takes place in the stars.

\(\begin{array}{l}4_{1}^{1}H\rightarrow{{}}\underset{Helium}{\mathop{_{2}^{4}He}}\,+\underset{Position}{\mathop{2{{_{+1}^{0}}^{e}}}}\,+27M\,e\,V\end{array} \)

Reactions with Organic Compounds

It reacts with many organic compounds in the presence of catalysts to give useful hydrogenated products of commercial importance. For example,

  • Hydrogenation of vegetable oils in the presence of nickel catalyst.
  • Hydroformylation of olefins to give aldehyde then into alcohol.

Uses of Hydrogen

  1. In the preparation of ammonia
  2. As a fuel in preparation of fuel gases, like water gas
  3. As a reducing agent in metallurgy
  4. As part of nuclear fusion, a large amount of energy is released by stars.

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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