Here's why:

* Inert gases are also known as noble gases. They are in Group 18 of the periodic table.

* Valence electrons are the electrons in the outermost shell of an atom, which are involved in chemical bonding.

* Neon has an electron configuration of 1s² 2s² 2p⁶. This means it has 2 electrons in the first shell and 8 electrons in the second shell.

Because it has a full outer shell, neon is very stable and unreactive, which is a characteristic of all noble gases.