NTA will shortly release the JEE Main Syllabus 2025 at jeemain.nta.ac.in. Last Year, the complete syllabus of JEE Main underwent some major changes. According to the latest syllabus guidelines, the weightage of Physics has dropped to 22.5%. Due to these changes in the syllabus, certain shifts in chapter-wise weightage have been observed. Atomic Structure are among such topics. It’s among the least weightage topics in JEE Main Physics Syllabus 2025. This chapter holds 1.39% weightage in the whole syllabus.

  • Atomic Structure is a part of the General Physics section, and every year around 2-3 questions are asked from this chapter. Due to the drop in weightage, you can expect 1-2 questions in JEE Main 2025.
  • Atomic Structure in JEE Mains Physics Syllabus 2025 covers all the basic concepts on units and measurements, fundamentals of units, dimensions etc.

Aspirants consider Atomic Structure as one of the Easiest Chapters in Physics for JEE Main 2025. Even though this chapter has the least weightage in the syllabus, to develop a strong foundation in physics, this particular chapter plays a pivotal role. Hence the candidates need to develop a clear understanding of this chapter. The list of most asked questions from this chapter will help the students with their preparation.

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Here are some common questions about atomic structure for the JEE Main exam:

  • How are atoms structured?
  • What are the locations, masses, and electrical charges of subatomic particles?
  • Where are valence electrons located?
  • How do you find the number of protons, electrons, and neutrons in an atom of an element?
  • How many electrons fit in each shell around an atom?
  • How do you read an electron configuration table?
  • How do you make a model of an atom?

Some important topics in atomic structure for the JEE Main exam include: Bohr model, Quantum mechanical model, Wave nature of electrons, Atomic spectra, and Ionization energy.

Atomic structure is a fundamental concept in chemistry that helps understand the properties of matter and the behavior of atoms. In the JEE Main exam, atomic structure is worth 6-8%.

Atomic Structure JEE Mains Questions -

List Of Most Asked Questions With Solutions

In the (JEE) Main, the topic of Physics and Measurement often features questions that have appeared multiple times in previous years. Many questions in this section are either repeated or follow similar patterns, with only minor changes, such as different numerical values or slight modifications in wording.Certain questions have been repeated as many as five times.

Here are some of the most frequently asked and repeated questions:

  1. Which of the following is not a correct statement regarding the characteristics of cathode rays? ( This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016)

A) They travel in straight lines.

B) They are affected by electric fields.

C) They are affected by magnetic fields.

D) They do not possess momentum.

Solution:

Option D is correct. Cathode rays possess momentum as they are made up of charged particles (electrons).

  1. Which of the following quantum numbers does not follow from the solution of the Schrödinger wave equation? (This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.)

    A) Principal quantum number

    B) Azimuthal quantum number

    C) Magnetic quantum number

    D) Spin quantum number

Solution:

Option D is correct. The spin quantum number does not arise from the Schrödinger wave equation.

  1. The ionization energy of hydrogen is 13.6 eV. What is the ionization energy of He⁺ in eV?

    A) 13.6

    B) 27.2

    C) 54.4

    D) 122.4

Solution:

Option C is correct. The ionization energy of He⁺ is calculated using the formula E = 13.6 * Z². For He⁺, Z = 2, so E = 13.6 * 2² = 54.4 eV.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. What is the de Broglie wavelength of an electron moving with a velocity of 10⁶ m/s? (mass of electron = 9.1 × 10⁻³¹ kg)

    A) 7.3 × 10⁻¹⁰ m

    B) 6.6 × 10⁻¹⁰ m

    C) 4.5 × 10⁻¹⁰ m

    D) 2.7 × 10⁻¹⁰ m

Solution:

Option A is correct. The de Broglie wavelength λ = h/mv, where h = 6.626 × 10⁻³⁴ J·s.

λ = (6.626 × 10⁻³⁴) / (9.1 × 10⁻³¹ * 10⁶) = 7.3 × 10⁻¹⁰ m.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. Which of the following orbitals will not exist according to quantum theory?

    A) 1p

    B) 2s

    C) 3d

    D) 3p

Solution:

Option A is correct. The 1p orbital cannot exist as the principal quantum number n = 1 cannot have l = 1 (which defines p orbitals).

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. The first ionization energy of magnesium is higher than that of sodium. This is because:

    A) Magnesium has a higher nuclear charge than sodium.

    B) Sodium has a higher nuclear charge than magnesium.

    C) Both have the same nuclear charge.

    D) Magnesium has a smaller atomic size than sodium.

Solution:

Option A is correct. Magnesium has a higher nuclear charge than sodium, making it more difficult to remove an electron.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. The energy of a photon is given by which of the following expressions?

    A) h/λ

    B) hc/λ

    C) hν

    D) both B and C

Solution:

Option D is correct. The energy of a photon can be expressed as both hc/λ and hν, where h is Planck’s constant, c is the speed of light, λ is the wavelength, and ν is the frequency.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. Which of the following transitions in the hydrogen atom corresponds to the emission of the photon with the shortest wavelength?

    A) n = 5 to n = 4

    B) n = 4 to n = 2

    C) n = 3 to n = 2

    D) n = 2 to n = 1

Solution:

Option D is correct. The n = 2 to n = 1 transition corresponds to the emission of a photon with the shortest wavelength as it involves the greatest energy difference.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. The uncertainty principle is mathematically expressed as:

    A) Δx Δp ≥ h/2π

    B) Δx Δp ≤ h/2π

    C) Δx Δp ≥ h/4π

    D) Δx Δp ≤ h/4π

Solution:

Option C is correct. The Heisenberg uncertainty principle is expressed as Δx Δp ≥ h/4π, where Δx is the uncertainty in position and Δp is the uncertainty in momentum.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.

  1. Which of the following series of lines in the hydrogen spectrum is in the visible region?

    A) Lyman series

    B) Balmer series

    C) Paschen series

    D) Brackett series

Solution:

Option B is correct. The Balmer series corresponds to transitions that result in the emission of visible light.

This question has been asked thrice - 30-Jan-2024 Shift 2, JEE Main 2020, JEE Main 2016.