CBSE Class 11-science Answered

main postulates of bohrs theory

Electrons revolve round the positively charged nucleus in certain definite circular orbits having certain definite energy.

ii) These are "stationary orbits " & Electrons can stay in these orbits without radiating energy.

iii) Electrons absorb or emit energy whenever they jump from one energy level to another in accordance with Planck's Quantization Rule.

          i.e.                           ΔE=hγ                 where,   ΔE is the change in energy

                                                                                    h is the Planck's constant

                                                                                                                   γ is the frequency of the of light emitted.

iv) Electrons revolve in only those circular orbits, in which the angular momentum of the electron is Quantized (Quantization Rule).

                                       i.e.                        mvr_n =nh/(2Π)                    n= 1, 2, 3, . .

An atom consists of a positively charged nucleus around which e^- revolve in definite quantized energy circular orbits of only certain radii.