Write a note on Neil Bohr's Atomic Theory.
Neil Bohr's atomic theory
In order to overcome the defects of Rutherford's atomic theory, Neil Bohr 1913 presented his atomic theory considering the Hydrogen atom as a model. Following are the main points of Neil Bohr's atomic theory.
1. Orbits/ Shells or Energy levels
The negatively charged electrons revolve around the positively charged nucleus in circular paths; these paths are called Orbits, Shells, or Energy Levels.
2. Relation b/w Energy of electrons and distance from the nucleus
The energy of an electron in an orbit is proportional to its distance from the nucleus. The farther the electron from the nucleus, the higher will be the energy and vice versa.
3. Fix energy of orbits
Electrons do not absorb or radiate energy whenever it remains in their own orbit;
it means that the energy of an orbit is
fixed.
4. Change in energy due to fall and down of electron in an orbit
Electrons absorb or radiate energy only when they move from one to another orbit. The absorbed or radiated amount of energy can be found by the following equation
∆E = E2 – E1 = hv
Where
- h is called Plank's constant and
- v is the frequency of radiation.
5. Residence of electrons in a particular orbits
Electrons can reside in any one of the orbits but can't stay in between the orbits.
6. Angular momentum of electrons
Electrons can reside in the orbits for which their angular momentum is an integral multiple of (h/2π)
i.e. mvr = nh / 2π
Where- m is the mass of the electron.
- v is the velocity of the electron.
- r is the radius of an orbit.
- h is the Plank’s constant (6.6262×10-34 j/sec), and
- n is the number of shell.
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