Question

After the completion of $n{p^6}$ electronic configuration, the next orbital will be filled by:
(A) (n+1)d
(B) (n+1)s
(C) (n+1)f
(D) none of the above

Answer 1

Hint: The electrons are arranged in a way that the orbitals having lower energy will be filled first. So, the orbital that immediately comes next to the np orbital in energy level will be filled by electrons.

Complete step by step answer:
 Here, we need to give the orbital which gets filled after $n{p^6}$ configuration. Let’s see how the electrons are filled into the orbitals and which rules dictate their arrangements.

- In the process of arrangement of electrons into the orbitals of atoms, mainly two rules are followed; Aufbau’s and Hund’s rule.
- Aufbau’s rule states that the electrons are arranged in a way that the orbitals that have lower energy are filled first. Hund’s rule states that electrons are filled in the orbitals having the same energy in a way that the spin of the electrons remains maximum. So, it is also called maximum spin multiplicity rule.
- We know that the maximum number of electrons that can be filled in a p-orbital is 6. We can see that there are 6 electrons in a given configuration. So, now the next electrons will be filled in another orbital.
- So, the new orbital in which the electron is to be filled is decided upon Aufbau’s rule. So, we need to find an orbital which is next to (higher energy) $n{p^6}$ orbital in the energy level.
- Now, the energy of the orbitals can be predicted by assigning the azimuthal quantum number (l) to the particular orbital and then adding its value to the principal quantum number value (n).
- Thus in other words, we can say that the more the value of (n+l), more its energy. s-orbital has l value of 0, p-orbital has l value of 1 and so on the l values of the orbitals are given.
- In that way, the next orbital to be filled will be (n+0) which will have the lowest energy and that zero refers to the s-orbital. So, the next orbital to be filled after $n{p^6}$ will be $(n + 1)s$.
So, the correct answer is “Option C”.

Note: According to Aufbau and Hund’s rules, the order of the orbitals to be filled by the electrons in the atoms is as follows:
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d,……