Noble Gases have eight electrons in their outermost orbit (except helium which has two electrons). As a result, they have a stable configuration. Group 18 elements are gases that are chemically unreactive, meaning they do not form many compounds. Be a result, the elements are referred to as inert gases. Noble gas elements, like the other group elements, display trends in their physical and chemical properties.  The noble gas family’s general configuration is ns2 np6 (except helium which has 1s2).

Group 18(Noble or Inert Gas Elements)-Characteristics, Physical & Chemical Properties, Trends, Characteristics, FAQs

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Noble Gases have eight electrons in their outermost orbit (except helium which has two electrons). As a result, they have a stable configuration. Group 18 elements are gases that are chemically unreactive, meaning they do not form many compounds. Be a result, the elements are referred to as inert gases. Noble gas elements, like the other group elements, display trends in their physical and chemical properties.  The noble gas family’s general configuration is ns2 np6 (except helium which has 1s2).

When the group’s members were found and named, they were assumed to be extremely rare as well as chemically inert, and hence were dubbed the rare or inert gases. However, it is now recognised that several of these elements are relatively abundant on Earth and across the cosmos, thus the term rare is deceptive. Similarly, the term inert has the disadvantage of connoting chemical passivity, implying that compounds of Group 18 cannot be produced. The term noble has long been used in chemistry and alchemy to describe the resistance of metals such as gold and platinum to undergo a chemical reaction.

Noble (Inert) Gases or Group 18 Elements

Noble or inert gases are elements in Group 18. They are named inert because they do not participate in any chemical reaction, hence they are chemically inert.

Helium, Neon, Argon, Krypton, Xenon, and Radon are all non-metallic elements of group 18.

In the periodic table, the zero group holds an intermediate position between the strong electronegative elements of the VIIA and strong electropositive elements of the IA groups, acting as a bridge. The noble gases are found in group 18 of the periodic table, which is located on the far right of the table. The 18th group members all have 8 electrons in their outermost shell.

  • Noble gas electronic configuration: Members of group 18 have eight valence electrons, which means they have eight electrons in their outermost orbit (except helium). As a result, they have a consistent octet configuration. Helium, on the other hand, has a duplet structure. The noble gas family’s general configuration is ns2 np6 (except helium which has 1s2).
  • Noble gas atomic radii: Members of group 18 have extremely small atomic radii. The atomic radii of noble gases grow down the group as the atomic number increases due to the addition of additional shells.
  • Noble gas ionisation enthalpy: Noble gases have eight valence electrons, which means they have eight electrons in their outermost orbit (except helium). As a result, they have a stable octet or duplet configuration. As a result, the elements of group 18 have extremely high ionisation enthalpies. Because of the increase in atomic size, the ionisation enthalpy of noble gases drops along with the group.

Properties of Noble Gases

  • Except for helium, all gases have the ns2, np6 arrangement. Except for helium, the differentiating electron reaches the p-subshell, and hence all of these atoms are p-block elements.
  • Except for helium, which has a 1s2 structure and a totally filled 1st shell, all noble gases have an outermost shell with a complete octet.
  • Because of their totally filled outer shell or stable structure, these elements, also known as noble gases, have no tendency to lose or gain electrons and so do not participate in chemical processes under normal conditions.
  • All of these group 18 elements are gases at normal temperature and pressure conditions. Rn and Og are radioactive noble gases, and the rest are present in trace amounts in the atmosphere.
  • Because of their insignificant presence in the atmosphere, these gases were given the label rare gases.
  • Because of their insignificant presence in the atmosphere, these gases were given the label rare gases.
  • Because they do not participate in any chemical reactions, they have been given the name inert gases.
  • However, in addition to these noble gases, a number of xenon compounds and two Krypton fluorides were created.
  • They are all monoatomic gases.

Physical Characteristics of Noble Gases

  1. These gases have no colour, taste, or odour.
  2. The Van der Waals forces between these elements’ particles are weak, but they become stronger as we progress down the group. This is due to an increase in the polarising capacity of the molecules.
  3. Because of their stable nature, these are monoatomic gases in their free state.
  4. Noble gases have low boiling and melting points. The low melting and boiling points of these gases are due to their weak Van der Waals force. These, however, rise as we progress along with the group.
  5. At extremely low temperatures, certain elements can be condensed. The ease of liquefaction rises down the group as the atom size increases.
  6. These are only marginally soluble in water. As we move down the group, solubility increases.
  7. The noble gases have the biggest atomic radii in their respective eras.
  8. The ionisation enthalpies of these noble gases are the highest in their respective periods because the electronic configuration is stable.

Chemical Characteristics of Noble Gases

This octet of electrons was assumed to be the most stable arrangement for the outermost shell of an atom in a chemical bonding theory established in 1916 by American chemist Gilbert N. Lewis and German scientist Walther Kossel. Although only noble-gas atoms had this arrangement, it was the state toward which all other element atoms tended in their chemical bonding. 

Certain elements satisfied this tendency by obtaining or losing electrons outright, resulting in the formation of ions; other elements shared electrons, generating stable combinations connected together by covalent bonds. The proportions in which atoms of elements bonded to create ionic or covalent compounds (their “valences”) were thus governed by the behaviour of their outermost electrons, which were dubbed “valence electrons” for this reason. This hypothesis described the chemical bonding of the reactive elements, as well as the relative inactivity of the noble gases, which came to be considered as their defining chemical property.

Sample Questions

Question 1: Group 18 Elements are not reactive? Why?

Answer:

The noble or inert gases are the group 18 elements. As the name implies, these are inert because they are chemically inert or non-reactive. Because of their totally filled outer shell, they have a stable electrical structure, which means they have no inclination to lose or gain electrons. Because these atoms have entire valence electron shells, the noble gases are exceedingly stable. These are highly unresponsive. Under typical conditions, they do not react or participate in any chemical reactions; nevertheless, there are some exceptions.

Question 2: Name the noble gases.

Answer:

Helium, argon, xenon, radon, neon, and krypton are examples of noble gases.

Question 3: How is the reactivity of noble gases under ordinary conditions?

Answer:

Under normal conditions, noble gases have no tendency to absorb or lose electrons. This is the only reason they are inert and do not participate in chemical reactions. Modern researchers have discovered that under certain conditions, noble gases can be induced to participate in a chemical reaction.

Question 4: What are noble gases why are they also called inert gases?

Answer:

Noble gases have no tendency to absorb or lose electrons under normal conditions. The only reason they are inert and do not participate in chemical reactions is because of this. Noble gases can be made to participate in a chemical process under particular conditions, according to modern researchers.

Question 5: Give reason why helium does not react with other elements.

Answer:

Helium has two electrons in its last orbital. It has a consistent electronic configuration. As a result, helium does not react with other elements.

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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