Question

why are group 18 elements called noble gases ?

Answer 1

Hey,
Ur answer is here,
They are helium, neon, argon, krypton, xenon, and radon. They were oncecalled inert gases because they were thought to be completely inert—unable to form compounds. This is a reasonable belief because the noble gases have a complete octet, making them very stable and unlikely to gain or lose any electrons.
That's why, they are called Noble or inert gases.
Hope it helps you ☺️

Answer 2

hi there...!!

As the valence shell of these elements are completely filled, i.e. have 8 electrons in last shell, they have zero valency. except He it has 2 electrons in valence shell.
Therefore, these elements do not react with any other elements.

Hope this helps you....!!