Bhor model of atom
1) atom has a nucleus at its centre which is positively charged and having high mass
2) electrons revolve only in those orbitals whose energy is fixed or whose velocity is fixed.
3) quantisation condition: electrons revolve only in those orbitals for which the angular momentum is integral multiply of h/2π
4) while revolving the electrostatic force between nucleus and electron act as centripetal force
q1.............q2 ×1
r². 4πε =
centripetal force:
Mv²/r
5) while revolving in a particular orbit an electron neither gains nor loses energy.
6) electron can accept energy and can lose energy
if an e accepts an energy, it jumps to higher energy level ( excitation of electron)
if an electron loses energy it recedes back to lower energy level (de excitation of e)
therefore electron can gain only that energy to which it's resultant must match to the other energies of shells similarly in loosing