**What are Quantum Numbers?**

Quantum numbers are basically those numbers which help us in describing the orbital occupied by an electron.

It tells us the following four things:

- The distance of the electron from the nucleus.
- The shape of the orbital
- The position of the orbital
- The spin of an electron

*There are four quantum numbers that help us to describe the location and behavior of an electron. They are:*

**Principal Quantum Number****Angular Quantum Number****Magnetic Quantum Number****Spin Projection Quantum Number**

**Principal Quantum Number**

The first is the principal quantum number (**n**) which describes the main energy level and size of an orbital i.e. the distance of the orbital from the nucleus. It is also referred to as a shell and the number of orbital in a shell and is given by n2.

**Angular Quantum Number**

The second is named as the azimuthal quantum number and also known as orbital angular momentum is denoted by **l**. It describes the shape and the type of orbital. There are 4 types of orbitals i.e. s, p, d, and f. The value of l ranges from 0 to n-1.

**Magnetic Quantum Number**

The third is the magnetic quantum number which is denoted by **m**. This describes the spatial orientation of the orbital. The s-orbital has only 1 possible position, p-orbital has 3 possible positions, d-orbital has 5 possible positions and f-orbital has 7 possible positions. The number of possible positions in an orbital is given as 2l + 1.

**Spin Projection Quantum Number**

The fourth is the spin quantum number (**m _{s}**). It deals with the spin of an electron in a subshell about an axis. The spin quantum number describes the intrinsic electronic spin in which +12 denotes the counterclockwise spin of an electron and −12 represents the clockwise spin. The maximum number of electrons in an orbital is two and these two electrons should have opposite spins.

The shape of the s-orbital is spherical, p-orbital is dumb-bell shaped. The shapes of d and f orbital are very complex and cannot be determined easily. It has been observed that d-orbital are pear-shaped.

*To explore more about quantum numbers and the orbital theory, stay tuned with Byju’s*