Question

State the order of filling atomic orbitals following Aufbau principle.

Answer 1

He gave a principle defining the order of the atomic orbital. The sequence in which various subshells are filled depend on the relative order of the energy of the sub-shells. The orbitals with lower energy get filled first.

Complete Step-by-step Solution:
Aufbau Principle gives the sequence or the order in which the filling of orbitals take place. Various highlights of the Aufbau principle are as follows:
In the ground state of any atom, the sub-shells or orbitals with relatively lower energy get filled first.When this contains a maximum quota of electrons then the next subshell of higher energy starts filling.
The orbitals are filled in order of increasing value of $(n + l)$.The sub-shells with lower value of $(n + l)$ get filled first.
In case,where, the more than one orbitals have the same value of $(n + l)$, the one with the lower value of principal quantum number i.e. the one with lower value of $n$ gets filled first.
The increasing order of energy of different orbital in a multi-electron atom is as follows:
$1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s$
and so on.
If we are asked to write the electronic configurations of any element in the periodic table, we will use Aufbau Principle to determine its electronic configuration.

Note: This is the general order of energies of the shell and electrons get fulfilled according to the capacity of the subshell. However there are some exceptions to it as well. This order may some time be disturbed a little in case of fulfilled and half-filled orbitals.This may show a little deviation there .