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

J. J. Thomson: Since discharge tube experiments suggested the presence of negatively charged particles in an atom which is neutral, J. J. Thomson suggested that electrons are embedded in a sphere of positive charge. The negative and positive charges are equal in magnitude, as a result of which an atom is electrically neutral.

E. Rutherford: The gold foil experiments of Rutherford suggested that all the positive charge is located in a very small space which is 10 times the radius of an atom. Therefore, Rutherford gave a model in which electrons are revolving around the nucleus in orbits.

Neils Bohr: To explain the stability of an atom and atomic spectra, Bohr suggested that electrons revolve around the nucleus in orbits which have fixed energy shells. There is a loss or gain in energy of electron when it moves from one orbit to the other.