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| Bohr’s atomic theory |
In since 1913 Niels Bohr a Danish Physicist
proposed a theory to remove the defects or weaknesses of Rutherford atomic
model. Niels Bohr contribute a lot in understanding the atomic structure and the quantum theories. For this useful contribution, the Niels Bohr also received the Nobel prize in 1922.
The Postulates of Bohr's Atomic Model
The following importants postulates of Bohr's atomic theory are as follow
- Electron in atom revolve around the nucleus of an atom in a definite circular path called orbitals and energy levels.
- The electron do not radiate energy as along as remain in an orbit.
- Electron can revolve only in an orbits of a fixed angular moment (mvr) given a
Where n is the
quantum number or orbit number having values 1, 2, 3,4,5,6 and 7 and h is the Plank’s constant having value
6.63 * 10-34 joules
and 2 is radius of circle and m is
mass of electron and v is velocity
of electron and r is radius of the orbit.
- When electron jumps from higher orbit to lower orbit it reduce energy and when electron jumps from lower orbits to higher orbit it gained energy.
The Merit and demerits of Bohr’s atomic model/theory
The Merits The following merits are as follow
- Bohr successfully explain many basic characteristic of atomic structure.
- His theory could not explain with classical mechanics therefore he started modern mechanics.
- He told that principle at macroscopic level do not apply at microscopic level.
- He explained the spectral lines of hydrogen atom successfully.
- He calculated the distance (radius) of the orbits and energy that an electron possesses in an orbit.
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The Demerits The following demerits are as follow
- He successfully explain the hydrogen atom but he was unable to explain the atom having many electrons.
- He also does not explain why there is a fixed number of orbits in which an electron reside in a hydrogen atom.
