9th Science NCERT Chapter 4
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– Charged Particles in Matter: Students should study about the nature of charged particles in matter, the presence of electrons and protons in atoms, and the concept of electric charge through various experiments【4:0†source】.
– The Structure of an Atom: Students should learn about the structure of an atom, including the arrangement of sub-atomic particles (electrons, protons, and neutrons), atomic number, mass number, isotopes, isobars, and the models proposed by J.J. Thomson, Rutherford, and Bohr【4:1†source】【4:2†source】.
– Valency of Elements: Students should understand the concept of valency, how it is determined based on the number of electrons in the outermost shell, and how to calculate valency for different elements like magnesium, aluminum, chlorine, and sulfur【4:2†source】.
– Atomic Number and Mass Number: Students should grasp the significance of atomic number (number of protons) and mass number (sum of protons and neutrons) in defining elements, along with the notation representing an atom's atomic number, mass number, and symbol【4:3†source】.
Compare the properties of electrons, protons and neutrons.
What are the limitations of J.J. Thomson’s model of the atom?
What are the limitations of Rutherford’s model of the atom?
Describe Bohr’s model of the atom.
Compare all the proposed models of an atom given in this chapter.
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