The elements in Group 18 of the periodic table are collectively called the noble gases. The group includes helium, neon, argon, krypton, xenon, radon, and the synthetic element oganesson.
Noble gases generally have full outer electron shells, which makes them unusually unreactive compared with many other elements. Under standard conditions, helium, neon, argon, krypton, and xenon are colorless, odorless, monatomic gases. Radon is also a gas but is radioactive, while oganesson is extremely short-lived and its bulk properties remain uncertain.
Their low reactivity gives noble gases many practical uses. Helium provides lift in balloons, argon shields hot metal during welding, and neon produces the familiar glow of advertising signs. Xenon is used in specialized lamps and has also been found in chemical compounds.
The older label “inert gases” is less precise because some noble gases, especially xenon, can form compounds. Group 18 is also sometimes called Group 0 or VIIIA in older systems, but “noble gases” is the standard modern name.