Neon: properties, production, and applications of the inert gas

Comprehensive overview of neon — the inert gas (Ne, atomic number 10): its key physical and chemical properties, industrial production by air separation, and applications from signage and lasers to cryogenics.

Author: Leandro Alegsa Creation date: November 13, 2022 Last updated: April 10, 2026

Neon is a chemical element with the symbol Ne and atomic number 10. It is a colorless, odorless, and tasteless noble gas that makes up a small fraction of Earth's atmosphere. As a member of the noble gas group, neon is chemically very unreactive under ordinary conditions.

Key properties

Atomic number: 10
Symbol: Ne
Standard atomic weight: about 20.18 u
Physical state at room temperature: colorless gas
Melting point: roughly 24.56 K
Boiling point: roughly 27.07 K
Stable isotopes in nature: 20Ne, 21Ne, 22Ne (20Ne is the most abundant)

Occurrence and production

Neon is a trace component of Earth's atmosphere, present at roughly 18 parts per million by volume. It is most commonly obtained industrially by fractional distillation of liquefied air, where neon is separated from other gases based on differences in boiling points.

Chemical behavior

Because neon has a complete outer electron shell, it shows extremely low chemical reactivity. Under normal laboratory conditions no stable neon compounds are known; only weakly bound van der Waals complexes and short-lived ionic species have been observed under extreme conditions in specialized experiments.

Uses

Neon is best known for its use in gas-discharge lighting. When an electric current passes through neon at low pressure, it emits a characteristic red-orange glow that is widely used in illuminated signs and artistic lighting. Neon also contributes to some types of gas lasers (for example, the helium–neon laser) and is used in certain high-voltage indicators and vacuum tubes. Because of its low boiling point, liquid neon serves as a cryogenic refrigerant in some scientific applications.

History

Neon was discovered in 1898 by Sir William Ramsay and Morris W. Travers in London while studying the components of liquefied air. The element's name derives from the Greek word neos, meaning "new." Commercial use of neon in illuminated signs began in the early 20th century and popularized the distinctive neon glow.

Safety

Neon is nonflammable and chemically inert, so it poses little direct chemical hazard. However, like other inert gases, it can displace oxygen in confined spaces and create an asphyxiation risk. Liquid neon is extremely cold and can cause severe cold burns on contact.

History

In 1894, argon was the first noble gas to be discovered by Lord Rayleigh and William Ramsay. In 1895, Ramsay also isolated helium, previously known only from the solar spectrum, from uranium ores. From the laws of the periodic table, he recognized that between helium and argon there must be another element with an atomic mass of about 20 u.

Therefore, from 1896 onwards, he initially investigated various minerals and meteorites and the gases emitted by them when heated or dissolved. Ramsay and his colleague Morris William Travers were not successful, however, helium and rarely argon were found. Also the investigation of hot gases from Cauterets in France and from Iceland brought no results.

Finally, they began to examine 15 litres of crude argon isolated from liquid air and to separate it by liquefaction and fractional distillation. The first element thus separated and detected on the flame spectrum was krypton, and on 13 June 1898 they finally succeeded in isolating a lighter element from the lower-boiling fraction of the crude argon. This Ramsay and Travers named neon, after the Greek νέος néos, German 'new'. A short time later, they were able to obtain another element, xenon, from the fraction containing krypton.

The first application of the newly discovered gas was the neon lamp developed in 1910 by the Frenchman Georges Claude: neon filled into a glass tube is excited to glow by high voltages.

Nucleosynthesis

Neon, especially the isotope ^20Ne, is an important intermediate product in the nucleosynthesis in stars, but is only formed during carbon burning. During helium burning at about 200 - ¹⁰⁶ K, ^{20Ne is} not formed due to the small capture cross section of ^16O for α-particles, only the isotopes ^21Ne and ^22Ne can be formed from the heavier ^18O. If the temperature and density of a star increase significantly after the helium has been consumed, carbon burning occurs, in which two carbon atoms fuse to form an excited magnesium isotope ^{24Mg*. This forms 20Ne} through α-decay.

$\mathrm{^{12}C \ + \ ^{12}C \longrightarrow \ ^{24}Mg \longrightarrow \ ^{20}Ne \ + \ ^{4}He}$

With a further increase in temperature and pressure, neon burning occurs, in which ^20Ne reacts in α-decay to ^16O or fuses with the resulting helium nuclei to form ^24Mg.

$\mathrm{^{20}Ne + \gamma \longrightarrow \ ^{16}O + \ ^4He}$

$\mathrm{^{20}Ne + ^4He \longrightarrow \ ^{24}Mg + \gamma}$

Due to the higher sensitivity of ^20Ne compared to ^16O to gamma radiation, this takes place before the reactions of the lighter oxygen nucleus, which are actually to be expected. Only after the end of the neon burning does the oxygen burning take place, in which heavier elements such as silicon, phosphorus and sulphur are formed from ^16O.

Author

Creation date: November 13, 2022

Last updated: April 10, 2026