Question

What is the electron configuration for chlorine?
A. $1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$
B. $\left[ {Ar} \right]4{s^1}$
C. $1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^2}3{d^5}$
D. $1{s^2}2{s^2}2{p^5}3{s^2}3{p^5}$

Answer 1

Hint: In this question use the concept of electronic configuration of elements i.e. given by general electronic configuration $1{s^2}2{s^2}2{p^x}3{s^y}........$ For example sodium has atomic number 11. The electronic configuration of sodium is $1{s^2}2{s^2}2{p^6}3{s^1}$. Use this to find the electronic configuration of chlorine.

Complete step-by-step answer:

In order to write the configuration of the chlorine electron we first need to learn the number of electrons from the Cl atom (there are 17 electrons). When we write the configuration we will put all 17 electrons in orbit around the Chlorine Atom nucleus.
In writing Chlorines electron configuration the first electrons are going to go into the orbital 1s. Since 1s can carry only two electrons in the orbital of the 2s the next 2 electrons for chlorine go. The next six electrons are going to go in orbital 2p. The orbital p can hold a maximum of six electrons. We 're going to put six in the 2p orbital, and put the next two electrons in the 3s. Since the 3s are now full we will move to the 3p where we will move to the 3p where the remaining five electrons will be placed. Therefore, the electron structure for chlorine would be $1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$
The atomic number of Chlorine (Cl) is 17. Thus its electronic configuration is $\left[ {Ne} \right]3{s^2}3{p^5}$ or $1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}$.
Hence the answer is option A.

Note: Electrons roam the nucleus in imaginary paths called shells or orbits. The electron is arranged into various orbits. The various orbits are named K, l , M, N ...... etc. There is no difference between the energies of the different subshells within a shell, the 3s, 3p, and 3d orbitals, for an atom which contains only one electron.