Question

Write down the electron distribution of chlorine atoms. How many electrons are there in the $L$ shell? (atomic number of chlorine is $17$)

Answer 1

In order to write the chlorine electronic configuration we first need to know the number of electrons for the chlorine. When we write the configuration we will put all $17$ electrons in orbitals around the nucleus of the chlorine atom. The symbols used for writing the electron configuration start with the shell number followed by the type of orbital and finally the superscript indicates how many electrons are in the orbital.

Complete answer:
The symbols used for writing the electron configuration start with the shell number followed by the type of orbital and finally the superscript indicates how many electrons are in the orbital. To calculate an electron configuration, divide the periodic table into sections to represent the atomic orbitals, the regions where electrons are contained. Groups one and two are the $s$-block, three through $12$ represent the $d$ block, $13$ to $18$ are the $p$-block and the two rows at the bottom are the $f$-block.
$KLMN$ represent energy levels given by Bohr theory and represented by principal quantum number $spdf$ represent orbitals within each of the shells given by sommerfield and represented by azimuthal quantum number.
In writing the electronic configuration for chlorine the first two electrons will go in the $1s$ orbital. Since $1s$ can hold only two electrons the next two electrons go in the $2s$ orbital. The next six electrons will go in the $2p$ orbital. The $p$ orbital can hold up to six electrons. We will put six in the $2p$ orbital and then put the next two electrons in $3s$. Since the $3s$if now full we will move to the $3p$ where we will place the remaining five electrons. Therefore, the electronic configuration will be $[Ne]3{s^2}3{p^5}$( $2,8,7$) and there are $8$ electrons in the $L$ shell.

Note:
There are different orbital shapes; each orbital can only hold two electrons max. There is a hierarchy, i.e. $s$ orbitals will be filled before $p$ orbitals which will be filled before $d$ orbitals and so on. This is the general rule but there are exceptions. The configuration notation provides an easy way for scientists to write and communicate how electrons are arranged around the nucleus of an atom. This makes it easier to understand and predict how atoms will interact to form chemical bonds.