Q19 of 21 Page 102

Geeta got a doubt, "Why atomic nucleus contains proton and neutrons inside it? Why can't electrons and neutrons?" Can you help to clarify her doubt? Explain.

Mass of electron is negligible compared to that of proton. Whereas the mass of proton is 2000 times of mass of electron.

Generally the heavy mass present in the nucleus. So the positive charged protons are present in the nucleus of an atom because of their heavy mass.


There exists force of repulsion between same charged particles. To reduce the repulsion force between protons in the nucleus, neutron exists in the nucleus. The electrons revolve around the nucleus in specified paths.


More from this chapter

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16

For the following statements, write T for True and F for False.

a. J.J. Thomson proposed that the nucleus of an atom contains only nucleons.


b. A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.


c. The mass of an electron is 1/2000 times that of proton.

 17

Fill in the missing information in the following table.

 18

How do you appreciate the efforts made by scientists to explain the structure of atom by developing various atomic models?

 20

Collect information about various experiments conducted and theories proposed by scientists starting from John Dalton to Niels Bohr and prepare a story with a title "History of atom".