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Syllabus

Structure of the Atom — Syllabus

Gujarat Board · Class 9 · Science

What Structure of the Atom covers in Gujarat Board Class 9 Science: 4 topics, for the 2026-27 session. Part of the Gujarat Board Class 9 Science syllabus.

45 questions25 flashcards3 formulas & key relations5 concepts

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An illustration of J.J. Thomson's atomic model, depicting an atom as a sphere of uniformly distributed positive charge with electrons (plums) embedded within it.
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4 Topics · Gujarat Board Class 9 Science · 2026-27

Topics in Structure of the Atom

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1. Charged Particles in Matter – Sub-Atomic Particles

  • Atoms are divisible and contain smaller particles called sub-atomic particles.
  • The three main sub-atomic particles are: Electron (e⁻), Proton (p⁺), and Neutron (n⁰).
  • J.J. Thomson discovered the electron.
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2. Atomic Models – Thomson, Rutherford, and Bohr

  • Thomson's Model (Plum Pudding / Watermelon Model): Atom is a positively charged sphere with electrons embedded in it like seeds in a watermelon or dry fruits in a Christmas pudding.
  • Thomson's model explained electrical neutrality but could NOT explain Rutherford's scattering results.
  • Rutherford's Alpha-Particle Scattering Experiment: Fast-moving alpha (α) particles were fired at a thin gold foil (1000 atoms thick).
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3. Distribution of Electrons in Shells (Bohr-Bury Rules)

  • The distribution of electrons in shells follows the Bohr-Bury scheme.
  • Rule 1: Maximum electrons in a shell = 2n², where n = shell number (1, 2, 3, 4...).
  • K shell (n=1): max 2 electrons. L shell (n=2): max 8 electrons. M shell (n=3): max 18 electrons. N shell (n=4): max 32 electrons.
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4. Valency

  • Valency is the combining capacity of an atom — how many bonds it can form.
  • Valency is determined by the number of electrons in the outermost shell (valence electrons).
  • If valence electrons ≤ 4: Valency = number of valence electrons (electrons lost or shared).

Key Concepts

Atoms consist of three fundamental particlesJErnest Rutherford conducted the famous alphaNiels Bohr improved Rutherford's model byJ

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Frequently Asked Questions

What are the important topics in Structure of the Atom for Gujarat Board Class 9 Science?
Key topics in Structure of the Atom include Charged Particles in Matter – Sub-Atomic Particles, Atomic Models – Thomson, Rutherford, and Bohr, Distribution of Electrons in Shells (Bohr-Bury Rules), Valency. Study these first, then practise questions on each for Class 9 exams.
How should I revise Structure of the Atom for Class 9 exams?
Learn the core ideas first, then work through the 45 practice questions on Structure of the Atom. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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All Gujarat Board Class 9 Science Syllabus

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