Question

What is shorthand electron configuration of $Al$ ?

Answer 1

To solve the given question, the concepts to be cleared are about Quantum number, shells, sub-shells, orbitals, Pauli Exclusion Principle, Aufbau Rule and P fund's Rule.
Quantum number is basically the address of an electron in an atom.Shells are the permitted orbits where an electron revolves with fixed angular momentum. Subshell is a division under a shell which contains orbital or orbitals.

Complete step by step solution:
Step-1 :
The formula for aluminium is $Al$ . Here,the total number of electrons is $13$ .
Step-2 :
The four quantum numbers are Principal Quantum Number which denotes the shell, Azimuthal Quantum Number denoting sub-shell, Magnetic Quantum Number and Spin Magnetic Number.
The sub-shells are s,p,d,f, . . . . . . and so on. They are filled on the basis of energy with $n+l$ rule.
Step-3 :
So, $Al$ can be represented as $1s^22s^22p^63s^23p^1$ . The above given configuration is long form. To write it in shorthand, we look at the nearest noble gas, where it is neon.
So, shorthand electron configuration is $[Ne]3s^23p^2$ .

Additional Information:
Pauli’s Exclusion Principle states that any $2$ electron can never have all the same $4$ quantum numbers.
Aufbau Rule explains the filling of electrons according to energy level.
P fund’s Rule explains that every orbital with one electron then fills another electron.
The magnetic quantum number differentiates orbitals in a given subshell. The l is always less than shell when $l=0,s;l=1,p;l=2,d;l=3,f;$ and so on.
$2$ Electrons are present in s, $6$ in p, $10$ in d and $14$ in f.

Note:
During the electronic configuration, always make sure to write with inner to outer shells but fill the electron according to energy. The energy of $3d$ is more than $4s$ but $3d$ is written inner to $4s$.