Give the order of energy of orbitals in a multi-electron atom.

(N/A) The energy order of orbitals in multi-electron atoms is determined by the $(n+l)$ rule,where $n$ is the principal quantum number and $l$ is the azimuthal quantum number. Orbitals with a lower $(n+l)$ value have lower energy. If two orbitals have the same $(n+l)$ value,the one with the lower $n$ value has lower energy.
The energy order of orbitals is:
$1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p$
Factors affecting the energy of orbitals:
$(i)$ The attraction of the orbital towards the nucleus and repulsion between electrons.
$(ii)$ The shielding effect provided by inner shell electrons.
$(iii)$ The penetration effect of orbitals,which follows the order $s > p > d > f$ for a given shell.
$(iv)$ The effective nuclear charge $(Z_{eff})$ experienced by the electrons.