The electronic configuration of an element is 1s2 2s2 2p6 3s2 3p5.What is the name of the element?

 The electronic configuration of an element is 1s2 2s2 2p6 3s2 3p5.This is the element chlorine.

Explanation:

1s2 2s2 2p6 3s2 3p5 means that 

●s subshell of first orbit or energy level has two electrons,

●s subshell of second orbit or energy level has two electrons,  

●p subshell of second orbit or energy level has six electrons,

●s subshell of third orbit or energy level has two electrons, 

● and p subshell of third orbit or energy level has five electrons.

Read:CO2 Lewis Structure



From 1s2 2s2 2p6 3s2 3p5 electron configuration,we get 2+2+6+2 + 5 = 17 electrons.


We know that electron's number is equal to proton number or atomic number for neutral atom.Since here there is no words about charge,we can say that 1s2 2s2 2p6 3s2 3p5 indicates the element whose atomic number is 17.


Now if you look at the periodic table,Cl has atomic number 17.

So 1s2 2s2 2p6 3s2 3p5 is electron configuration of Chlorine(Cl).