Here's why:

* Noble gases are very stable: They have a full outer shell of electrons, making them extremely unreactive.

* No need to bond: Because they are already stable, they don't need to bond with other atoms to achieve a full outer shell.

* Exist as single atoms: As a result, they exist as individual atoms (monatomic) in their natural state.

Examples of noble gases include:

* Helium (He)

* Neon (Ne)

* Argon (Ar)

* Krypton (Kr)

* Xenon (Xe)

* Radon (Rn)