Inert gases /ˈɪnərt ˈɡeɪsɪz/ (Latin: iners – inactive), rare gases – chemical elements belonging to the 9th group of Mendeleev’s periodic system: helium He (order number 2), neon Ne (10), argon Ag (18), krypton Kg (36), xenon Xe (54) and radon Rn (86). Of these, only radon is a radioactive element with no stable isotope. I. g. due to the strength of the outer electron shell of their atoms (helium has 2 electrons, the remaining I. g. has 8 electrons), they are extremely weak chemically (that’s where the name I. g. comes from).
Ex. Inert gases such as helium and neon are often used in various industrial applications, as they are non-reactive, providing stable and controlled environment.