Defect of Bohr's atomic model
A). Based on contradictory theory. This theory is based on two opposing theories such
Defect of Bohr's atomic model
as law of classical mechanics and quantum theory. Bohr applied the classical mechanics to describe the electionic motions in atoms. Bohrs retained the essential spirit of Rutherford's atomic model which is based on classical mechanics on the other hand, the quantization of angular momentum of electron is based on quantum mechanics,
b). Applicable for uni-electronic system only. This theory is applicable only for uni- electronic chemical species but not for multi- electronic chemical species for example: this theory is applicable for hydrogen of hydrogen like species such as He+ , Li++ .
c. Unable to explain the fine structure of spectra:
when hydrogen specrta are observed through powerful spectroscope for single spectra line of the ordinary hydrogen spectrum, several closely spaced line lines are observed. Bohr's atomic model cannot
this spliting of spectral lines
d. Unable to explain Zeeman effect and stark effect:
It does not explain the splitting of spectral lines into different event lines under the influence of magnetic field ( zeeman effect) and electronic field ( satark effect)
e. It could not explain about about dual nature of election :
Election behaves as both particle as well as well . This is known as dual nature of electron and couldn't explain about electron.
f. It could not explain about Heisenberg's uncertainty principle .
Disadvantages (short coming) of Bohr's atomic model
1. No explanation of fine structure or existance
of additional quantum number When hydrogen spectrum is observed by means of high resolving microscope (spectroscope) several
closely spaced spectral lines are found which are called spectra of multiple structures. Bohr unable to explain the origin such spectra Principle quantum number suggested by Bohr was not sufficient to explain origin of fine spectra i.e subdivision of orbit into suborbit are necessary. That means there are some quantum number which are also into the existence.
2. No explanation for the spectra of multi-electron system
Bohr theory was able to explain the spectra given by single election system but he couldn't explain about spectra of multielectron system Enamplet He explain spectrum of single electron like hydrogen, Helium(He+) , Lithium (Li++), Beryllium( Be++).
3) No explanation of electron moving in 3 dimensional space :
According to Bohr the motion of election is limited to single (plane), but actually electron move in 3 dimensional space around the nucleus.
4) Dual nature of election and heisen berg's principle
According to the den beroglie, electron behaves as both matter and wave where as Bohr treated elecron as matter only. According to hersen berg accurate measurement of position and velocity of a very small particle like election is not possible. These assumption are not included in bohr atomic model .
5) No explanation of Zeeman and stark effect
The splitting of spectral line into still thinner lines due to the presence of strong magnetic field and strong electric field are respectively called zeeman effect and stark effect.Bohr was unable to explain such effects.
😄😃🎉🎉😃
ReplyDelete