Compare all the proposed models of an atom given in this chapter.

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Chapter 4 NCERT Class 9 Science SOLUTIONS

5. Compare all the proposed models of an atom given in this chapter.

Question:

Compare all the proposed models of an atom given in this chapter.

Answer:

Thomson’s atomic model	Rutherford’s atomic model	Bohr’s atomic model
No explanation about nucleus	Nucleus is explained	Nucleus is explained
The positive charge exists in the form of a sphere.	A positive charge, called proton, is present inside the nucleus.	A positive charge called proton is present inside the nucleus.
Electrons are studded in a positively charged sphere	Electrons keep revolving around the nucleus in orbits.	Electrons keep revolving in fixed orbits. (in energy levels) around the nucleus.
This is a nuclear model	Rutherford’s model had many drawbacks.	Bohr improved Rutherford’s model.

More NCERT Questions

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(All Q's of this Chapter solved)

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Complete the following table:

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Which one of the following is a correct electronic configuration of sodium ? (a) 2,8 (b) 8, 2, 1 (c) 2, 1, 8 (d) 2, 8, 1

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Number of valence electrons in Cl– ion are— (a) 16 (b) 8 (c) 17 (d) 18

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Isotopes of an element have (a) the same physical properties (b) different chemical properties (c) different number of neutrons (d) different atomic numbers

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Rutherford’s alpha particle scattering experiment was responsible for the discovery of. (a) Atomic (b) Electron (c) Proton (d) Neutron

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For the following statements, write T for true and F for false.

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Composition of the nuclei of two atomic species X and Y are given below : Give the mass number of X and Y. What is the relation between the two species ?

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If Z = 3, What would be the valency of the element ? Also name the element.

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Na+ has completely filled K and L shells. Explain.

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Summarise the rules for writing of distribution of electrons in various shells for the first eighteen elements.

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What are the limitations of Rutherford’s model of the atom ?

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Describe Bohr’s model of the atom.

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What are the limitations of J.J. Thomson’s model of the atom?

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Write the electronic configuration of any one pair of isotopes and isobar

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For the Symbol H, D and T tabulate three sub-atomic particles found in each of them.

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With the help of given find out the mass number of oxygen and sulphur atom.

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If number of electrons in an atom is 8 and number of protons is also 8, then (i) What is the atomic number of the atom? (ii) What is the charge on the atom?

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If the K and L shells of an atom are full, then what would be the total number of electrons in the atom?

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If K and L shells of an atom are full, then what would be the total number of electrons in the atom?

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Write the distribution of electrons in Carbon and Sodium atoms.

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Helium atom has an atomic mass of 4u and two protons in its nucleus. How many neutrons does it have?

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Name the three Sub-atomic particles of an atom.

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What do you think would be the observation if the a-particle Scattering experiment is carried out using a foil of a metal other than gold?

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Draw a Sketch of Bohr’s model of an atom with three shells.

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On the basis Rutherford’s model of an atom, which sub-atomic particle is present in the nucleus of an atom?

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On the basis of Thomson’s atomic model explain how the atom is neutral as a whole.

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What are canal rays?

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