Question

Enlist the features of Bohr’s model of an atom. How did he correct Rutherford's model?

Answer 1

In order to solve this question, we should know about Planck hypothesis of light such that light is made up of particles called photons which travel at speed of light in vacuum and here we will discuss about main features of Bohr’s model of an atom and later figure out how this new model overcame Rutherford model.

Complete Step By Step Answer:
Bohr suggested a modern approach to describe atomic model and some of his main postulates on which whole atomic model is based upon are listed as:
(a) An atom consists of small positively charged nuclei in the centre around which negatively charged particles called electrons move around it in circular orbits.
(b) The size of the nucleus is very small as compared to that of an atom.
(c) Electrons revolve in circular orbits around the nucleus in only those possible orbits where its angular momentum is integral multiple of $\dfrac{h}{{2\pi }}$ and its related as $mvr = n\dfrac{h}{{2\pi }}$ where, m is mass of electron, v is velocity of electron, r is radius of circular orbit and h is Planck’s constant.
(d) The circular orbits are known as the shell of an atom name as for orbit number $n = 1,2,3..$ as K shell, L shell, M shell respectively.
(e) All energy levels are not allowed for electrons, only quantized energy levels are allowed and this energy is proportional to $E \propto - \dfrac{{{Z^2}}}{{{n^2}}}$ where n is number of orbit, and Z is atomic number of an atom.
So, these were the main features of the Bohr atomic model.
Now, as according to Rutherford model electron is revolving around nuclei and it must lose all of its energy with time and need to fall into the nucleus but it doesn’t happen so, Bohr suggested that electrons don’t fall because only quantized energy levels are allowed for electrons and whenever an electron lose its energy it emits radiation and jump into lower energy level whereas when light falls on electron it gains energy and jump into higher energy level. This explanation corrects the Rutherford model of an atom.

Note:
It should be remembered that, Bohr atomic model is not the complete model to study the atom’s behaviour because the Bohr model is only applicable to single electron atoms such as hydrogen atoms and it also fails to explain the splitting of spectral lines under the presence of magnetic field.