Why are elements belonging to group 18 called noble gas elements?

• Elements from group 18 are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).
• The outermost shell of the group 18 elements has eight electrons and has achieved a stable electronic configuration.
• These gases are unreactive or inert because they do not gain, lose, or share electrons. Because they are found in such small amounts in the earth's atmosphere, they are also known as noble gases. (It's less than 1%.)