On the periodic table, neon is the first noble gas after helium in atomic-number order.
Neon has atomic number 10 and occupies group 18 and period 2. Its atoms have a full outer electron shell, which makes neon exceptionally unreactive under ordinary conditions. In atomic-number order, helium comes first, followed by neon, then argon, krypton, xenon, and radon.
Neon is a colorless, odorless gas at room temperature. When an electric current passes through low-pressure neon, it produces a distinctive reddish-orange glow. This property made neon valuable in illuminated signs, although many signs called “neon” use other gases to create different colors.
Neon was discovered in 1898 by William Ramsay and Morris Travers while they were studying liquefied air. It should not be confused with nitrogen, which is also a period-2 gas but belongs to group 15 and is chemically more reactive.