Question

Which of the following questions, the Bohr's atomic model was not able to provide an answer for:

• A. Why electrons have a license to "not" follow Maxwell's law of radiation in certain orbits?
• B. Why the transitions between certain orbits are more favorable?
• C. Why does the electron revolve around the nucleus and can't remain stationary?
• D. Why is it necessary for the electrons to emit a photon while transitioning from higher to lower orbits?

Answer 1

Answer: (A), (B)

Why the transitions between certain orbits are more favorable?

a) Bohr never claimed that the Maxwell's laws are wrong, but boldly proposed that, in certain orbits where angular momentum is
$(L=\frac{nh}{2\pi })$
Electrons do not follow Maxwell's laws. No proof was given for this statement - it was just a model.
b.In the line spectra of Hydrogen, certain wavelengths were present in large intensities than others, which implies the probability of certain transitions being more. None of the postulates discuss this issue.
c. Electrons if stationary will be pulled by positively charged nucleus due to electrostatic attraction, to avoid this it must revolve around in circular motion so that the coulombic attraction serves as the centripetal force and keeps electron revolving around. Bohr's atomic model uses this picture.
d.Bohr derives the energy of each permitted orbit and concludes that the energy of electrons in higher orbits is more than in that of the lower orbits.
Hence if an electron jumps from higher energy orbit to lower, it must loose energy .That energy comes in the form of photon.