Atomic structure is a very important chapter of Physical Chemistry. It is the most fundamental and basic chapter. It helps you to understand whole of chemistry and also the modern physics. Every year 2 to 3 questions are asked from this chapter in JEE Advanced and 1 to 2 questions in JEE Mains. A good understanding of topics can easily fetch you full marks from this chapter for it is an easy chapter to score if you are a bit careful.

Atomic structure helps you in understanding the meaning of various terms like Atomic mass, Atomic Radius, Size of an atom, Electronic Configuration, Orbitals and its Structure etc. Also, these terms are used in other chapters like Periodic Table and Chemical Bonding.

The syllabus of Atomic Structure for JEE is same as the syllabus provided by the CBSE in NCERT textbooks. To become proficient on certain topics you have to strengthen its concepts by practicing more and more questions from different books. You can use NCERT textbook in the beginning, and later go in for advanced level books such as “P. Bahadur” or “O. P. Tandon” that cover all the major topics in depth.

## Important Books

- NCERT: This is no doubt the most important book for Physical Chemistry. Concepts are fairly explained in this book.
**You should be comfortable with every line of Atomic Structure given in NCERT for JEE Mains**. Most of the questions are asked directly without any twist so you have to mug up each and every definition, formula, properties, and examples. - Numerical Chemistry (P. Bahadur): Best book for Physical Chemistry as it contains a good theory as well as a large number of solved examples. It also includes varieties of numerical to make your concepts strong.
- Physical Chemistry by O. P. Tandon: Refer this book if you want deep knowledge on any topic of Atomic Structure. It builds the concepts from very basic level to advanced level.
- To complete your preparation, you are required to solve the past year questions that are asked in JEE Mains/Advanced (36 years Chapter wise Solved Paper by Arihant Publications) to get thorough with the pattern/level of questions asked in both the exams.

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## Important Topics

**Discovery of Electron Proton and Neutron**: Mug up the theory part of this topic given in NCERT. Sometimes a direct question is asked in JEE Mains.**Atomic models**: Dalton’s atomic model and its postulates, Rutherford’s atomic model and alpha particles scattering experiment, Bohr’s atomic model and its postulates are of the utmost importance. So, pay special attention to these.**Dual nature of matter**: Practice numerical problems on Photoelectric effect, De Broglie’s matter waves, and Heisenberg uncertainty principle. One question is sure shot in the exam from these topics.- Expression and Formula for the energy of electron (kinetic energy, potential energy, and total energy), radius of electronic shell, frequency & wavelength of light during transitions of electron and angular momentum of electron in an orbit are frequently used to solve the numerical problem and should be learned properly. You need to practice a lot of numerical problems on each of these topics.
**Quantum numbers**: These include Principal quantum number (n), Angular Momentum Quantum Number (l), Magnetic Quantum Number (m) and Electron Spin Quantum Number (s). Special attention must be given to these. Though it’s very easy, but sometimes JEE has framed tricky questions from these.- Shapes of s, p and d orbitals: Electronic configuration of elements (up to atomic number 36), Aufbau’s Principle, Pauli’s exclusion principle, Hund’s rule, rules for filling electrons in atomic orbitals and exchange energy are some important topics. Orbital overlap and covalent bonds and Orbital energy diagrams for homonuclear diatomic species also, to name a few more. Questions are frequently asked from these topics.

## Some Basic Tips

- First study this chapter from NCERT Textbook thoroughly. Read the chapter two or three times and try to understand each and every concept clearly. Move to Numerical Problems only when you are clear with all the concepts.
- Start with solved examples given in the book and then move to the unsolved ones. Once you solve all the questions given in NCERT textbook, you can move to the other advanced level books (P. Bahadur or O. P. Tandon) and try to solve more tricky problems to gain in depth knowledge of the chapter.
- Most of the numerical problems are from
**Hydrogen Spectrum**and**Bohr’s Theory**. These two topics are very important, especially for JEE Mains. Try to solve as many questions as you can from these two topics. - Most of the formula (total energy, radius of orbit, angular momentum) have the same terms but different exponential number, so there is a chance of mixing them up. Make sure you use the right formula depending on the question asked. It is advised to remember the expressions with a simplified value for all the constants and not the long one (PI, Plank’s constant, Rydberg’s constant etc.)
- You must know how to write the quantum numbers for any electron in a given shell of a given atom. Understanding of Pauli’s Exclusion, Aufbau’s Principle, Hund’s Rule of Maximum Multiplicity is essentially important to correctly predict the quantum numbers of an electron.
- For numerical questions, you must use/learn shortcut formulas which would enable you to arrive at the answer quickly and hence save time. If you face problem in remembering a particular formula, have a look at its logic or derivation so that you can easily derive it on your own when the need comes if forgotten.
- Do not forget to learn the formula for the number of Nodes (both radial node and angular node) as sometimes questions are asked based on simply this formula. Hence a scoring formula.
- You will face a lot of calculation problem in this chapter, for this you can use technique of approximation i.e. approximate the values of the constants to make calculations easy and quick. Take the value of Rydberg’s constant as 10^7 instead of 1.097 x 10^7, similarly the value of Plank’s constant as 6 x 10^(-34) instead of 6.626 x 10^(-34) .

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