question_answer 127)

  Hydrogen atom has only one electron, so mutual repulsion between electrons is absent. However, in multielectron atoms mutual repulsion between the electrons is significant. How does this affect the energy of an electron in the orbitals of the same principal quantum number in multielectron atoms?                

Answer:

  In hydrogen atom, energy of different orbitals depends on the principal quantum numbers only. \[1s<2s=2p<3s=3p=3d<4s=4p=4d=4f...\]In multielectron species, the energy of orbitals depends on both ?n' and ?f? \[1s<2s<2p<3s<3p<4s<3d\] Lower is the values of \[(n+l)\], lower is the energy of orbitals. If \[(n+l)\] values are same then the orbital with lower value of t n' will have lesser energy.