Question

The electron configuration for an excited atom:
A. $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}$
B. $1{s^2}2{s^2}{p^6}3{s^2}3{p^6}4{s^2}$
C. $1{s^2}2{s^2}{p^6}3{s^2}3{p^6}4{s^1}$
D. $1{s^2}$
E. $1{s^2}2{s^2}2{p^6}3{p^1}$

Answer 1

The energy of 3s orbital is lower than 3p orbital. So, it will be filled first.

Complete step by step answer:
An excited state means that the valence electron has moved from its ground state orbital which has the lowest available energy to some other higher energy orbital.
So, if the valence electron in any electronic configuration is in the higher energy orbital, that element is said to be in an excited state.
For Example: The electronic configuration of the carbon (C) atom is given below
$1{s^2}2{s^1}2{p^3}$
The total energy of the electrons in this Carbon atom can be lowered by transferring an electron from the 2p orbital to the 2s orbital. So, we can say this Carbon atom as the excited state of a Carbon atom.
$1{s^2}2{s^1}2{p^3} \to 1{s^2}2{s^2}2{p^2}$
Coming back to the question, 3s orbital being lower than in energy than 3p orbital will be filled first.
Therefore, the electron configuration for an excited atom will be $1{s^2}2{s^2}2{p^6}3{p^1}$ .

Therefore, the correct answer is option (E)

Note: Atoms may occupy different energy states. The energy states are discrete which means they occupy at specific values only.
The ground state electronic configuration of an atom is the same as the regular configuration in which the electrons are in the lowest energy level whereas the excited state electron configuration shows when an electron is excited and jumps into the higher orbital.
An electron is normally in its ground state but after absorbing energy, it jumps from the ground state to an excited state. For an electron to move from its own orbit to the orbit in the higher energy state, it must overcome the energy between its current orbit and the orbit it is going to.