A periodic Table is the arrangement of all the elements in the known universe based on either atomic weight or atomic number. There are various failed attempts to arrange the known elements so that all the elements with similar properties are arranged together. But in 1863 Russian chemist Dmitri Mendeleev, gave Mendeleev’s Periodic Table which is the most successful attempt of that time. In modern-day, scientists using Mendeleev’s Periodic Table as a base created a long-form periodic table which is called Modern Periodic Table.

Periodic Table Trends: Atomic Radius, Ionization Enthalpy, Electron Gain Enthalpy, Electronegativity

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What is Periodic Table?

A periodic Table is the arrangement of all the elements in the known universe based on either atomic weight or atomic number. There are various failed attempts to arrange the known elements so that all the elements with similar properties are arranged together. But in 1863 Russian chemist Dmitri Mendeleev, gave Mendeleev’s Periodic Table which is the most successful attempt of that time. In modern-day, scientists using Mendeleev’s Periodic Table as a base created a long-form periodic table which is called Modern Periodic Table.

In this table, Periods are made up of elements that are organized horizontally (from left to right) and the group is made up of elements that are arranged vertically (from top to bottom). We’ll learn about the periodic trends in these periods and groups in this article.

A periodic Table is the arrangement of all the elements in the known universe based on either atomic weight or atomic number. There are various failed attempts to arrange the known elements so that all the elements with similar properties are arranged together. But in 1863 Russian chemist Dmitri Mendeleev, gave Mendeleev’s Periodic Table which is the most successful attempt of that time. In modern-day, scientists using Mendeleev’s Periodic Table as a base created a long-form periodic table which is called Modern Periodic Table.

Periodic trends are specific patterns that are present in the periodic table that illustrate different aspects of a certain element. They were discovered by the Russian chemist Dmitri Mendeleev in the year 1863. Major periodic trends include atomic radius, ionization energy, electron affinity, electronegativity, valency and metallic character. These trends exist because of the similar electronic configuration of the elements within their respective groups or periods and because of the periodic nature of the elements. These give a qualitative assessment of the properties of each element. Let’s take a look at them in detail,

Atomic Radius

The atomic radius is the distance between an atom’s nucleus and its outermost shell. The periodic trend of atomic radius across a period – Atomic radius steadily lowers as we move from left to right in a period. This is due to the fact that as we move left to right in a period, the atomic number of the elements increases, causing the nuclear charge to increase while the number of shells in elements remains constant. Moving from top to bottom in a group, atomic radii gradually rise as nuclear charge and the number of shells grows.

Exception: Noble gases exhibit extraordinary behaviour. When compared to the preceding halogen atom, the atomic radii of inter gases rapidly increase. The explanation for this unusual behaviour is that in the case of noble gases, atomic radius relates to van der Waal’s radius, whereas in the case of other elements, it refers to the covalent radius.

Valence Electrons 

The electrons in an atom’s outermost shell are referred to as the atom’s valence electrons. The amount of valence electrons grows as we move left to right across a period in the periodic table. Valence electrons remain consistent across a group. It denotes that elements in the same group have the same number of valence electrons. Hydrogen, lithium, and sodium elements, for example, are all found in the first group and all have the same number of valence electrons, which is one. 

Valency  

An atom’s valency is its ability to combine. Moving left to right across a period in the periodic table, valency increases first, then declines. There is no change in valency among members of a group. The valency of elements from the same groups is the same.

Metallic Character of The Elements  

The metallic property of elements reduces as we move left to right across a period in the periodic table. The metallic property of elements grows as we progress up the periodic table from top to bottom.

Non – Metallic Character of The Elements  

The nonmetallic property of elements grows as we move left to right across a period in the periodic table. The non-metallic nature of a group of periodic table elements reduces as we proceed from top to bottom.

Reactivity of Elements

Metal reactivity is determined by its electropositive nature. As a result, the more metallic the element is, the more electropositive it is, and the more reactive it is. As the metallic character decreases from left to right, so does the reactivity. Although the reactivity of nonmetals rises as one moves from left to right over time. As a result, we can deduce that as we move left to right in a period, the reactivity of elements steadily diminishes until group thirteen, when it begins to increase. 

Melting Point

The melting point is the total amount of energy necessary to convert a solid into a liquid. If the link between the atoms of elements is strong, it takes a lot of energy to break the bond. It gets smaller as we go from top to bottom. Non-metals, on the other hand, rise from top to bottom of the periodic table. Among metals, carbon has a high melting point. Boron has a high melting point when compared to other semi-metals. Tungsten has a high melting point when compared to other metals.

Boiling Points of Elements  

Metal boiling points fall gradually from top to bottom in a group. While the boiling temperatures of nonmetals grow from top to bottom in a periodic table group.

Electron Affinity (Electron Gain Enthalpy)

Electron affinity is the energy released when an electron is added to an atom. As you move from left to right across a period, the electron affinity generally increases. This is because the added electron experiences a greater attractive force from the nucleus as the nuclear charge increases. But there are exceptions to electron affinity trends i.e., noble gases, fluorine, Group 2, Group 14 and Group 15. 

Down a group, the electron affinity generally decreases. This is because as you move down a group, the atomic size increases due to the addition of extra energy levels or shells. With larger atomic size, the outer electrons are farther from the nucleus, resulting in weaker attractive forces between the nucleus and the incoming electron. Therefore, atoms in lower groups have less affinity for an additional electron.

Electronegativity

Electronegativity is a measure of an atom’s ability to attract electrons. As you move from left to right across a period, the electronegativity generally increases. This is because the increased nuclear charge makes the atom more electronegative.

Similar to electron affinity, electronegativity tends to decrease down a group. As you move down a group, the atomic size increases and the valence electrons are located farther from the nucleus. This increased distance reduces the effective nuclear charge experienced by the valence electrons, making it more difficult for the atom to attract additional electrons. Consequently, the electronegativity decreases down the group.

Ionization Enthalpy

Atomic radius shrinks as a period progresses from left to right. As a result, as the size of an atom diminishes, so does the attractive attraction between the nucleus and the outermost electrons. As a result, ionization energy often increases over the periodic table. 

However, when we look at the pattern of ionization enthalpy in groups, we can see that it falls from top to bottom in a group. This is owing to the fact that as the number of shells grows down the group, the outermost electrons will be further away from the nucleus, resulting in a lower effective nuclear charge. Second, the shielding effect increases down the group as the number of shells grows, resulting in a decrease in ionization energy.

Electron Gain Enthalpy

As we move from left to right in a period, the electron gain enthalpy becomes increasingly negative. We can conclude from the patterns of attributes in the periodic table that the elements at the two extremes of the periodic table are most reactive (note: noble gases have entirely filled shells; so they are least reactive) and the elements in the middle are the least reactive. The elements on the extreme left are alkalis, which easily shed electrons to produce cations. 

On the other hand, halogens, the elements on the extreme right that easily gain electrons to create an anion – are present. It is related to the metallic and non-metallic properties of elements whereas while travelling from left to right in a period, metallic properties drop while nonmetallic properties increase. Metallic properties rise in a group while non-metallic properties diminish. In addition, as a period progresses from left to right, metallic features decrease and nonmetallic properties increase. In a group, metallic traits increase while nonmetallic properties decrease.

The below-attached picture shows the general trend in the properties of elements. The direction of arrow shows the increase in property on moving in the direction of arrow.

A periodic Table is the arrangement of all the elements in the known universe based on either atomic weight or atomic number. There are various failed attempts to arrange the known elements so that all the elements with similar properties are arranged together. But in 1863 Russian chemist Dmitri Mendeleev, gave Mendeleev’s Periodic Table which is the most successful attempt of that time. In modern-day, scientists using Mendeleev’s Periodic Table as a base created a long-form periodic table which is called Modern Periodic Table.

The following table is the summary of all the periodic trends in the properties of different elements.

DecreasesIncreases
IncreasesRemains constant
First Increases then decreaseRemains constant
DecreasesIncreases
IncreasesDecreases
DecreasesIncreases after Group 13
Varies (General trend: Decreases for Metals)Varies (General trend: Increases for Metals)
Varies (General trend: Decreases for Metals)Varies (General trend: Increases for Metals)
IncreasesDecreases
IncreasesDecreases

Question 1: What is meant by the electronic configuration of an element?

Answer: 

An element’s electronic configuration is a symbolic representation of how its atoms’ electrons are arranged across different atomic orbitals. A standardised notation is used for expressing electron configurations, in which the energy level and type of orbital are written first, followed by the number of electrons present in the orbital expressed in superscript.

Question 2: Is it easier to remove an electron from sodium or aluminium?

Answer:

It doesn’t take much energy to extract one electron from a sodium atom in order to generate a Na+ ion with a filled-shell electron configuration. The second aluminium ionisation energy is bigger than the first, and the third is much higher.

Question 3: What is the penetration effect?

Answer:

The proximity of an electron in an orbital to the nucleus is referred to as penetration. It can be viewed as the relative density of electrons near an atom’s nucleus for each shell and subshell. Looking at the radial probability distribution functions, we can see that the electron density of s orbitals is higher than that of p and d orbitals.

Question 4: What is the effect on metallic character as we move in a periodic table?

Answer:

As we advance down the group, the metallic character rises because atomic size increases, resulting in easy electron loss. It, on the other hand, lowers as we move from left to right over time.

Question 5:  What are some metallic characteristics?

Answer:

The qualities associated with the metals contained on the periodic table are referred to as metallic character. These characteristics include metallic shine, hardness, malleability, thermal conductivity, and others.

Q1: What is Periodic Table?

Answer:

The periodic table is a tabular arrangement of chemical elements, organized based on their atomic number, electron configuration, and recurring chemical properties. It provides a comprehensive overview of the elements and their relationships.

Answer:

Periodic table trends are regular patterns or trends observed in the properties of elements as you move across a period (horizontal row) or down a group (vertical column) in the periodic table. These trends help us understand the behavior and characteristics of elements.

Q3: What is Atomic Radius?

Answer:

Atomic radius refers to the size of an atom. It is measured as the distance from the nucleus to the outermost electron shell of an atom. Atomic radius generally decreases across a period and increases down a group in the periodic table.

Q4: What is Electronegativity?

Answer:

Electronegativity is the measure of an atom’s ability to attract electrons towards itself in a chemical bond. It indicates the relative strength with which an atom can hold onto its electrons. Electronegativity tends to increase across a period and decrease down a group.

Q5: What is Ionization Energy?

Answer:

Ionization energy is the amount of energy required to remove an electron from a neutral atom and form a positive ion. It is a measure of the atom’s ability to hold onto its electrons. Ionization energy generally increases across a period and decreases down a group.

Q6: What is Electron Affinity?

Answer:

Electron affinity is the energy change that occurs when an atom gains an electron to form a negative ion. It represents the tendency of an atom to accept an electron. Electron affinity generally increases across a period and decreases down a group.

Q7: What is Metallic Character?

Answer:

Metallic character refers to the extent to which an element displays metallic properties such as conductivity, malleability, and luster. Metallic character tends to decrease across a period and increase down a group.

Q8: What is Reactivity?

Answer:

Reactivity refers to the tendency of an element to undergo chemical reactions. It can vary depending on the element’s position in the periodic table. Generally, metals are more reactive on the left side of the periodic table, while nonmetals are more reactive on the right side.

Answer:

Melting and boiling points generally increase across a period and decrease down a group in the periodic table. This trend is primarily influenced by the strength of atomic bonding within the elements.

Q10: What is Trend for Ionic Size on Periodic Table?

Answer:

Ion size generally decreases across a period and increases down a group. Cations (positively charged ions) are smaller than their parent atoms, while anions (negatively charged ions) are larger due to changes in the electron configuration.

Answer:

Chemical reactivity varies across the periodic table. Generally, metals tend to be more reactive as you move down a group due to the ease of losing electrons. Nonmetals tend to be more reactive as you move up a group because they have a higher tendency to gain electrons.

Q12: What is Trend of Number of Valence Electrons on Periodic Table?

Answer:

Valence electrons are the electrons present in the outermost energy level of an atom. The number of valence electrons generally increases by one from left to right across a period and remains constant within a group (column) in the periodic table.

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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