Electronic Configuration is the arrangement of electrons in orbitals around an atomic nucleus. Electronic Configuration of a molecule refers to the distribution of electrons in various molecular orbitals.
The number of electrons in bonding and antibonding molecular orbitals of a molecule or molecular ion can be calculated from its electronic configuration.
Table of Contents
What is Electronic Configuration?
Electronic Configuration refers to the arrangement of electrons among the orbitals of an atom or molecule. Electronic configurations are typically produced by conventional notation (especially for elements having a relatively large atomic number). In such instances, a shortened or condensed notation may be employed instead of the normal notation. In shortened notation, the sequence of entirely filled subshells that correspond to a noble gas’s electronic configuration is replaced by the noble gas’s symbol in square brackets.
As a result, sodium’s abbreviated electron configuration is [Ne] 3s1 (the electron configuration of Neon is 1s2 2s2 2p6, which can be abbreviated to [He] 2s2 2p6.
Electronic Configuration Definition
Electronic configuration is defined as the arrangement of electrons at different energy levels around an atomic nucleus.
Electronic Configuration allows us to know the number of electrons present in the outermost shell, hence, as a result, electron configurations can be used for the following purposes:
Determining an Element’s Valency
Predicting the qualities of a group of elements (elements with similar electron configurations tend to exhibit similar properties).
The interpretation of Atomic Spectra, etc.
Electronic configuration provides a structured way of representing the arrangement of electrons within an atom, indicating the energy levels and sublevels they occupy.
Electronic Configuration in Periods
Electronic configuration of the elements in periods can be found by using following points:
The period of the element is the value of n, the primary quantum number, for the valence shell.
The number of electrons that can be accommodated by different energy levels varies.
The maximum number of electrons that can be accommodated in an energy shell is given by 2n2, where n is the energy level. It is the greatest number of electrons that a given energy level can allow. So the first energy level (K shell) can hold up to 2 electrons, the second (L shell) up to 8 electrons, the third (M shell) up to 18 electrons, and so on.
The second period begins with Lithium and Beryllium, both of which have three and four electrons, respectively, and so the final electrons reach level two.
The third period begins with Sodium and finishes with Argon, filling the 3s and 3p orbitals in that order. There are eight elements in this period as well.
The level 4s are filled first in the fourth period with n = 4. It all starts with potassium. However, we know that the 3d orbital must be full before the 4p orbital can be filled. Scandium is the first of the 3d transition elements. The 3d orbital gets completely filled with electrons in the case of zinc.
The level 5s are filled first in the fifth period with n = 5. The 4d transition series, which begins with the Yttrium, dominates this time. The 5p orbital is completely filled by Xenon at the end of the period.
With n = 6, the sixth period has 32 elements, with electrons filling the 6s, 4f, 5d, and 6p orbitals. Cerium signifies the entry of electrons into the 4f orbital, resulting in the lanthanide series of 4f-inner transition elements.
The radioactive elements with electrons filling the 7s, 5f, 6d, and 7p orbitals belong to the seventh period with n = 7. Similar to period 6, this period causes electrons to fill the 5f orbital, giving rise to the actinide series of 5f-inner transition elements.
Electronic Configuration in Groups
The outermost shells of elements in the same group have the same number of electrons, resulting in identical valence shell electrical configurations. As a result, the characteristics and chemistry of elements in the same group follow a similar pattern.
An example of the electronic configuration of elements in the same group is, Lithium(Li) and Sodium(Na) both are in the same group thus, their electronic configuration is,
Lithium (LI) = [He] 2s1
Sodium (Na) = [Ne] 3s1
Filling of Atomic Orbitals
We fill the atomic orbital with the electrons in accordance with these three rules,
Aufbau Principle
Pauli Exclusion Principle
Hund’s Rule
i.e. these three rules guide us to fill electrons in the atomic orbitals. Now, let’s learn about them in detail.
Aufbau Principle
The name of the Principle Aufbau is taken from the German word Aufbeen, which means “to build up”. According to the Aufbau Principle, electrons will occupy lower energy orbitals before moving on to higher energy orbitals. The energy of an orbital is calculated by adding its Primary quantum Number(n) and Azimuthal Quantum Number(l) or using the (n+l) rule.
According to this principle, electrons are filled in the following order:
There are a few exceptions to the Aufbau Principle, such as Chromium and Copper. These exceptions can occasionally be explained by the stability offered by half-filled or fully-filled subshells.
Pauli Exclusion Principle
According to the Pauli Exclusion Principle, an orbital can only hold a maximum of two electrons with opposite spins, i.e. no two electrons in the same atom have the same values for all four quantum numbers in an orbital.
As a result, if two electrons have the same Principle, Azimuthal, and Magnetic numbers, they must have opposite spins.
Hund’s Rule
Hund’s Rule specifies the order in which electrons are filled in all subshell orbitals. Hund’s Rule rule states that every orbital in a particular subshell is occupied by an electron before a second electron enters the subshell.
The electrons in orbitals with only one electron all have the same spin to maximize the total spin (or the same values of the spin quantum number).
Representation of Electronic Configuration
Electronic configuration of an atom is represented using a standardized notation system that indicates the distribution of electrons among the various atomic orbitals. Electronic Configurations are represented as follows:
Shell Designation: Each electron shell is represented by a number ‘n’, where n= 1, 2, 3,….. This number corresponds to the principal quantum number.
Subshell Designation: Each shell is further divided into different subshell that are represented using the notation of subshells (s, p, d, f).
Orbital Filling Order: Electrons are then filled in orbitals from lowest energy orbital to highest according to Aufbau Principal. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.
Electron Count: Number of electrons occupying each orbital is indicated by a superscript following the orbital designation. For example, 1s2 represents that 1s orbital contains 2 electrons.
Writing Electron Configuration
For Writing Electron Configuration of an element, we must know the basic information about the element like atomic number, no. of electrons, shells, etc. The electronic configuration is typically represented using the notation of subshells (s, p, d, f) and the number of electrons in each subshell. For example, the potassium element has atomic number 19. And has 19 electrons which will be placed in s and p sub-shell.
The electronic configuration can be written as 1s2 2s2 2p6 3s2 3p6 4s1. Its 19 electrons can be divided into different shells in a manner,
K shell (n = 1) = 2,
L shell (n = 2) = 8,
M shell (n = 3) = 8, and
N shell (n = 4) = 1.
Electronic Configurations of First 20 Elements
The electronic configuration of the first twenty elements of the periodic table is shown in the table added below,
Electronic Configuration of an element is the symbolic representation of how the electrons of that atoms are arranged across different atomic orbitals.
What are Three Rules used while Writing Electronic Configuration of Elements?
The three rules used in filling the atomic orbital or writing the Electronic configuration of an elements are,
Aufbau Principle
Pauli’s Exclusion Principle
Hund’s Rule of Maximum Multiplicity
How are Groups and Periods related to Electron Configuration?
Groups are determined by the number of valence electrons and periods are determined by the number of electron shells.
Why are Electronic Configurations of an Element Important?
Electron configurations of an element is important because it provide insight into the chemical behavior of elements by assisting in the determination of an atom’s valence electrons. It also helps in separating elements into four different blocks,
s-block
p-block
d-block
f-block
This makes studying various elements easy.
What is Pauli Exclusion Principle?
Pauli’s Exclusion Principle states that, an orbital can only hold a maximum of only two electrons with opposite spins, i.e. one with clockwise spin, and other with anti-clock wise spin.
Define Electronic Configuration.
Electronic configuration of an atom refers to the distribution of its electrons among the various atomic orbitals.
What is Hund’s Rule of Maximum Multiplicity?
Hund’s Rule of Maximum Multiplicity or simply Hund’s Rule specifies the order in which electrons are filled in all of a subshell’s 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.
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 Scheme
Marks
Volumetric Analysis
08
Salt Analysis
08
Content Based Experiment
06
Project Work
04
Class record and viva
04
Total
30
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 theapproval 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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