What is inside the atom
Kerala Board · Class 9 · Science
Summary of What is inside the atom for Kerala Board Class 9 Science. Key concepts, important points, and chapter overview.
Overview
This chapter explores the fascinating world inside atoms, revealing how scientists discovered that atoms are not indivisible as originally thought by Dalton, but contain smaller particles called sub-atomic particles. Through various experiments and models, we learn about electrons, protons, and neut
Key Concepts
Atoms contain three types of particles
Atoms contain three types of particles: electrons (negatively charged, negligible mass), protons (positively charged, mass 1836 times electron), and n
J
J.J. Thomson proposed that atoms are spheres of uniform positive charge with electrons embedded like plums in a pudding. This model suggested that pos
Based on alpha particle scattering experiments
Based on alpha particle scattering experiments with gold foil, Rutherford discovered that atoms have a small, dense, positively charged nucleus at the
Niels Bohr proposed that electrons move
Niels Bohr proposed that electrons move in fixed circular orbits (energy levels) around the nucleus without radiating energy. These orbits are labeled
Electrons are arranged in shells following
Electrons are arranged in shells following specific rules: maximum electrons in a shell = 2n², inner shells fill before outer shells, and each sub-she
Learning Objectives
- Understand the discovery of sub-atomic particles and their properties
- Learn about different atomic models proposed by Thomson, Rutherford, and Bohr
- Explain the structure of atoms and arrangement of electrons in shells
- Define and calculate atomic number, mass number, and valency
- Understand isotopes and their applications in daily life
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What is inside the atom covers several key topics that are frequently asked in Kerala Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
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Sources & Official References
- Kerala Board of Public Examinations — keralapareekshabhavan.in
- National Education Policy 2020 — education.gov.in
Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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