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Atomic Structure formula sheet

Every formula in the Atomic Structure chapter for JEE Main, with one line on when it applies. Topic 1 is open to everyone; sign in free to read all 26 and download the PDF.

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How we count: 7× asked means 7 past JEE Main questions in the PrepWiser bank needed that formula, and "last" is the latest year one appeared. ★ marks formulas asked 8 or more times.

Subatomic particles

Atomic notation
6× asked, last 2026
ZAX:neutrons=A−Zelectrons=Z−(ion charge)\begin{aligned}&{}^A_Z\mathrm X:\quad \text{neutrons}=A-Z\\&\text{electrons}=Z-\text{(ion charge)}\end{aligned}
Isoelectronic, 10 e−^-: NX3−\ce{N^3-}, OX2−\ce{O^2-}, FX−\ce{F-}, NaX+\ce{Na+}, MgX2+\ce{Mg^2+}, AlX3+\ce{Al^3+}; 18: SX2−\ce{S^2-} … ScX3+\ce{Sc^3+}.
Electron constants
4× asked, last 2023
e=1.602×10−19 C,me=9.109×10−31 kgeme=1.76×1011 C kg−1\begin{aligned}&e=1.602\times10^{-19}\ \text{C},\qquad m_e=9.109\times10^{-31}\ \text{kg}\\&\frac e{m_e}=1.76\times10^{11}\ \text{C kg}^{-1}\end{aligned}
Proton ≈ 1836 mem_e; neutron slightly heavier, no charge.

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24 more formulas in 6 topics

Radiation and the photon, Bohr model of hydrogen-like species, Hydrogen spectrum, Dual nature and uncertainty, Quantum numbers and orbitals and Orbital energies and configuration. Read the first part free. Sign in free with Google to read the rest and download the PDF.

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Radiation and the photon

  • Wave relations4×
  • Photon energy11×
  • Photoelectric effect11×

Bohr model of hydrogen-like species

  • Bohr's postulates4×
  • Radius of the nnth orbit9×
  • Energy and ionisation energy9×
  • Speed, KE and PE5×

Hydrogen spectrum

  • Rydberg formula10×
  • First line and series limit13×
  • Number of spectral lines2×
  • Moseley

Dual nature and uncertainty

  • de Broglie wavelength9×
  • de Broglie wave in an orbit5×
  • Heisenberg uncertainty9×

Quantum numbers and orbitals

  • Quantum numbers11×
  • Counting orbitals and electrons10×
  • Orbital angular momentum2×
  • Nodes13×
  • 2s wave function8×
  • Shapes and nodal planes4×

Orbital energies and configuration

  • Energies of orbitals14×
  • Filling order9×
  • Exceptional configurations11×
  • Ions; magnetic moment9×

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About 170 past JEE Main questions from this chapter, with instant answer checking and step-by-step solutions where available. Free, and you can start without signing up.

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Version 1, October 2026. Free to share for study, as it is. Please don't sell it or remove the PrepWiser name.

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