What does Structure of Atom cover for NEET Chemistry?

11 lessons: Aufbau Pauli Hund, Bohr Limitations, Bohr Model Hydrogen, Dual Nature de Broglie, Electronic Configuration, EM Radiation Photoelectric, Half Filled Full Filled Stability, Heisenberg Uncertainty, Hydrogen Spectrum, Orbital Shapes and Quantum Numbers.

How often has Structure of Atom come up in NEET past papers?

Our set of verified past papers has 9 questions from this unit, from NEET 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.

Is the Structure of Atom material free?

Yes. All 11 lessons and 88 practice questions are free, with no login needed.

Structure of Atom

11 lessons

Topic index in NCERT order

11 of 11 lessons by the NCERT chapter they teach from, in book order. The page is the first printed page of your NCERT book the lesson cites; PYQs are the past NEET questions on that topic.

Class 11 Chemistry, Chapter 2

EM Radiation Photoelectricp. 301 PYQ
Hydrogen Spectrump. 450 PYQs
Bohr Model Hydrogenp. 463 PYQs
Bohr Limitationsp. 490 PYQs
Dual Nature de Brogliep. 500 PYQs
Heisenberg Uncertaintyp. 500 PYQs
Quantum Numbersp. 562 PYQs
Orbital Shapesp. 602 PYQs
Aufbau Pauli Hundp. 620 PYQs
Electronic Configurationp. 621 PYQ
Half Filled Full Filled Stabilityp. 640 PYQs

Aufbau Pauli Hund

8 MCQsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Bohr Limitations

8 MCQs6 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Bohr Model Hydrogen

8 MCQs3 PYQs2 revision cardsWorked example

Direct Application (3)Easy Recall (3)Calculation (2)

Dual Nature de Broglie

8 MCQs3 revision cardsWorked example

Direct Application (3)Easy Recall (2)Calculation (2)Concept Trap (1)

Electronic Configuration

8 MCQs1 PYQsWorked example

Calculation (1)Easy Recall (3)Direct Application (3)Concept Trap (1)

EM Radiation Photoelectric

8 MCQs1 PYQsWorked example

Easy Recall (4)Direct Application (2)Calculation (1)Concept Trap (1)

Half Filled Full Filled Stability

8 MCQsWorked example

Easy Recall (3)Direct Application (3)Calculation (1)Concept Trap (1)

Heisenberg Uncertainty

8 MCQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (2)

Hydrogen Spectrum

8 MCQs5 revision cardsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Orbital Shapes

8 MCQs2 PYQsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Quantum Numbers

8 MCQs2 PYQsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Past-paper questions from this unit

9 questions from NEET 2021, 2022, 2023, 2024, 2025, 2026. Answers verified against NTA official keys.

By year in our set: 2021 (2) · 2022 (2) · 2023 (1) · 2024 (2) · 2025 (1) · 2026 (1)

Lesson: Orbital Shapes

NEET 2026

Consider the schematic plots of orbital wavefunction (ψ_r) against distance (r) from the nucleus, shown in the figure. The figure representing two radial nodes in the orbital is

NTA Answer: Option 3(final)

Report an error · Every fix is public: corrections log

Lesson: Bohr Model Hydrogen

NEET 2025

Energy and radius of first Bohr orbit of He+ and Li2+ are [Given RH = 2.18 × 10⁻¹⁸ J, a0 = 52.9 pm]

1En(Li 2+) = –8.72 × 10⁻¹⁶ J; rn(Li2+) = 17.6 pm En(He+ ) = –19.62 × 10⁻¹⁶ J; rn(He+ ) = 17.6 pm

2En(Li 2+) = –19.62 × 10⁻¹⁸ J; rn(Li2+) = 17.6 pm En(He+ ) = –8.72 × 10⁻¹⁸ J; rn(He+ ) = 26.4 pm

3En(Li 2+) = –8.72 × 10⁻¹⁸ J; rn(Li2+) = 26.4 pm En(He+ ) = –19.62 × 10⁻¹⁸ J; rn(He+ ) = 17.6 pm

4En(Li 2+) = –19.62 × 10⁻¹⁶ J; rn(Li2+) = 17.6 pm En(He+ ) = –8.72 × 10⁻¹⁶ J; rn(He+ ) = 26.4 pm

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Bohr Model Hydrogen

NEET 2024Revised key

The energy of an electron in the ground state (n = 1) for He+ ion is –x J, then that for an electron in n = 2 state for Be3+ ion in J is

1–x

2−x/9

3–4x

4−(4/9)x

NTA Answer: Option 1(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Quantum Numbers

NEET 2024Revised key

Match List I with List II List I List II (Quantum Number) (Information provided) A. m I. Shape of orbital l B. m II. Size of orbital s C. l III. Orientation of orbital D. n IV. Orientation of spin of electron Choose the correct answer from the options given below :

1A-I, B-III, C-II, D-IV

2A-III, B-IV, C-I, D-II

3A-III, B-IV, C-II, D-I

4A-II, B-I, C-IV, D-III

NTA Answer: Option 2(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Quantum Numbers

NEET 2023

The relation between nₘ, (nₘ = the number of permissible values of magnetic quantum number (m)) for a given value of azimuthal quantum number (l), is

1l = 2nₘ + 1

2nₘ = 2l² + 1

3nₘ = l + 2

4l = (nₘ − 1)/2

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Orbital Shapes

NEET 2022

Identify the incorrect statement from the following.

1The shapes of dxy, dyz and dzx orbitals are similar to each other; and − 22 xy d and 2 z d are similar to each other.

2All the five 5d orbitals are different in size when compared to the respective 4d orbitals.

3All the five 4d orbitals have shapes similar to the respective 3d orbitals.

4In an atom, all the five 3d orbitals are equal in energy in free state.

NTA Answer: Option 1(final)

Report an error · Every fix is public: corrections log

Lesson: Bohr Model Hydrogen

NEET 2022

If radius of second Bohr orbit of the He+ ion is 105.8 pm, what is the radius of third Bohr orbit of Li2+ ion?

1158.7 Å

2158.7 pm

315.87 pm

41.587 pm

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: EM Radiation Photoelectric

NEET 2021

A particular station of All India Radio, New Delhi broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light 108 ms–1] c = 3.0 ×

121.92 cm

2219.3 m

3219.2 m

42192 m

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Electronic Configuration

NEET 2021

From the following pairs of ions which one is not an iso-electronic pair?

1Fe²⁺, Mn²⁺

2O²⁻, F⁻

3Na⁺, Mg²⁺

4Mn²⁺, Fe³⁺

NTA Answer: Option 1(final)

Report an error · Every fix is public: corrections log

Exam traps and common mistakes in this unit

Lesson: Bohr Model Hydrogen

Trap

Hydrogen-like Z² factor

Category: Similar Terms

Student forgets Z² scaling when applying Bohr formulas to He⁺ (Z=2) or Li²⁺ (Z=3).

When it triggers

Question involves hydrogen-like ion (He+, Li2+, etc.).

How to avoid

E_n = -13.6 × Z²/n² eV. r_n = (0.529/Z) × n² Å. He+: 4× more bound than H. Li²⁺: 9× more bound. Always include Z².

Lesson: Electronic Configuration

Trap

Cr / Cu electronic configuration anomaly

Category: Inorganic Exception

Student writes Cr as [Ar]3d⁴4s² (expected) instead of actual [Ar]3d⁵4s¹. Same for Cu: actual [Ar]3d¹⁰4s¹ (one e⁻ promoted from 4s to 3d).

When it triggers

Question asks for ground-state electronic configuration of Cr (Z=24) or Cu (Z=29).

How to avoid

Half-filled (d⁵) and fully filled (d¹⁰) configurations have extra stability from exchange energy and symmetry. Cr and Cu adopt these configurations by promoting one 4s electron.

Lesson: Bohr Model Hydrogen

Mistake

Drops Z² factor when applying Bohr formulas to He⁺ or Li²⁺.

Root cause: formula misuse

Correction

Always include Z². E_n = -13.6 × Z²/n². For He+: 4× more energetic than H. For Li²⁺: 9×.

Lesson: Half Filled Full Filled Stability

Mistake

Writes Cr as [Ar]3d⁴4s² (expected) instead of actual [Ar]3d⁵4s¹. Same for Cu.

Root cause: concept gap

Correction

Half-filled (d⁵) and full-filled (d¹⁰) configurations have extra exchange-energy stability. Cr and Cu adopt these by promoting one 4s electron.

Formulas in this unit

Lesson: Bohr Model Hydrogen

Bohr energy (hydrogen-like)

E_{n} = - 13.6 \frac{Z ^{2}}{n ^{2}} eV

Energy of nth orbit. Negative (bound). Ground state H: -13.6 eV.

Symbol	Quantity	SI Unit
E_n	orbit energy	eV
Z	nuclear charge	-
n	principal	-

Valid when

Hydrogen-like atom
Non-relativistic

Lesson: Bohr Model Hydrogen

Bohr radius (hydrogen-like)

r_{n} = (0.529 \overset{˚}{A}) \frac{n ^{2}}{Z}

Radius of nth Bohr orbit for hydrogen-like atom of nuclear charge Z.

Symbol	Quantity	SI Unit
n	principal quantum number	-
Z	nuclear charge	-
r_n	orbit radius	Å

Valid when

Hydrogen-like (one-electron) atom
Non-relativistic

Lesson: Dual Nature de Broglie

de Broglie wavelength

λ = h / (m v)

Wavelength associated with moving particle of momentum mv.

Symbol	Quantity	SI Unit
h	Planck 6.626e-34	J*s
m	mass	kg
v	velocity	m/s

Valid when

Non-relativistic

Lesson: Heisenberg Uncertainty

Heisenberg uncertainty

Δ x Δ p \geq \frac{h}{4 π}

Position and momentum cannot both be known with arbitrary precision.

Symbol	Quantity	SI Unit
Δx	position uncertainty	m
Δp	momentum uncertainty	kg*m/s

Valid when

Quantum scale; meaningful only when Δx, Δp comparable to atomic dimensions

Lesson: Hydrogen Spectrum

Rydberg formula (H spectrum)

\frac{1}{λ} = R_{H} Z^{2} (1/ n_{1}^{2} - 1/ n_{2}^{2})

Spectral wavelengths of hydrogen-like atoms. Lyman (n1=1, UV), Balmer (n1=2, visible), Paschen (n1=3, IR).

Symbol	Quantity	SI Unit
lambda	wavelength	m
R_H	Rydberg 1.097e7	1/m
Z	nuclear charge	-
n1, n2	integers, n2>n1	-

Valid when

One-electron atom

NEET question patterns in this unit

Lesson: Aufbau Pauli Hund

Write electronic configuration, especially handling Cr/Cu anomalies and ions.

InterpretationMedium

Common distractors

misses cr cu anomaly

Writes 3d⁴4s² instead of 3d⁵4s¹

Lesson: Bohr Model Hydrogen

Bohr energy difference between two levels; compute photon energy/wavelength using Rydberg or E_n formulas.

Multi StepMedium

Common distractors

forgets z squared

Drops Z² for hydrogen-like

Lesson: Quantum Numbers

Given orbital (e.g. 3p_z) or electron, identify n, l, m_l, m_s. Or check forbidden quantum number combinations.

InterpretationEasy

Common distractors

uses wrong l range

Uses l ≤ n instead of l < n

Questions about this unit

What does Structure of Atom cover for NEET Chemistry?: 11 lessons: Aufbau Pauli Hund, Bohr Limitations, Bohr Model Hydrogen, Dual Nature de Broglie, Electronic Configuration, EM Radiation Photoelectric, Half Filled Full Filled Stability, Heisenberg Uncertainty, Hydrogen Spectrum, Orbital Shapes and Quantum Numbers.
How often has Structure of Atom come up in NEET past papers?: Our set of verified past papers has 9 questions from this unit, from NEET 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.
Is the Structure of Atom material free?: Yes. All 11 lessons and 88 practice questions are free, with no login needed.