Neon
Neon is a noble gas so chemically inert that it forms virtually no compounds at all, existing only as isolated, unreactive atoms. It's best known for the warm reddish-orange glow it gives off in electrified glass tubes, the effect that first made "neon lights" famous.
- Group · Period
- 18 · 2
- At room temp
- gas
- Melts at
- 24.56 K
- Density
- 0.0008999 g/cm³
- Discovered
- 1898
Uses
Neon’s signature use is in the glowing glass tubes of neon signs, where an electric current passed through low-pressure neon gas produces its characteristic warm orange-red light. Beyond signage, neon is used in certain types of lasers, in some vacuum tube components, and mixed with other gases in indicator lights and high-voltage signal equipment where a visible, reliable glow is useful.
Liquid neon also has a niche role as a cryogenic refrigerant. While it can’t get quite as cold as liquid helium, it has a much greater cooling capacity per unit volume, which makes it a practical choice for certain scientific and industrial cooling applications where extremely low temperatures aren’t required.
History
Neon was discovered in 1898 by British chemists William Ramsay and Morris Travers, who were systematically investigating liquid air by evaporating it and studying the gases left behind. After already having identified argon and krypton through similar work, they isolated a new lightweight gas and named it neon, from the Greek word “neos,” meaning “new.” Its glowing properties in electrified tubes were noticed soon after discovery, setting the stage for its later fame in signage.
Fun facts
- Pure neon glows a distinctive reddish-orange when electrified, the original source of the term 'neon sign,' even though many modern colorful signs use other gases entirely.
- Neon is only a trace gas in Earth's atmosphere, despite being one of the more abundant elements in the universe as a whole.
- It's one of the least chemically reactive elements known, forming essentially no stable compounds under normal conditions.
Frequently asked questions
Do all colorful 'neon signs' actually contain neon gas?
No — true neon gas produces the classic reddish-orange glow, but many other colors in modern signage come from different noble gases, gas mixtures, or mercury vapor combined with colored glass or phosphor coatings. 'Neon sign' has become a generic term even when the tube contains something else.
Why is neon so unreactive?
Neon has a completely full outer shell of electrons, which is an exceptionally stable configuration. With no tendency to gain, lose, or share electrons, it has essentially no drive to bond with other atoms, making it one of the most chemically inert elements on the periodic table.
Where does the neon used in signs and lighting come from?
It's extracted from ordinary air. Air is cooled until it liquefies, then separated through fractional distillation, a process that also yields other atmospheric gases. Because neon makes up only a tiny fraction of air, large volumes have to be processed to collect a usable amount.
Isotopes
20 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Ne-20 stable | 90.48% | Stable | — | -7,041.93 keV | 8,032.24 keV | — |
| Ne-21 stable | 0.27% | Stable | — | -5,731.78 keV | 7,971.71 keV | — |
| Ne-22 stable | 9.25% | Stable | — | -8,024.72 keV | 8,080.47 keV | — |
Show all 20 isotopes
| Ne-15 | — | 0.59 MeV | Two-proton emission (100%) | 40,215.37 keV | 4,868.73 keV | 5.90 × 105 eV |
| Ne-16 | — | 80 keV | Two-proton emission (100%) | 23,986.78 keV | 6,083.18 keV | 8.00 × 104 eV |
| Ne-17 | — | 109.2 ms | Electron capture / beta-plus decay (100%), ECP (95.2%), ECA (2.77%) | 16,500.45 keV | 6,640.5 keV | 4.18 × 10-15 eV |
| Ne-18 | — | 1672 ms | Electron capture / beta-plus decay (100%) | 5,317.62 keV | 7,341.26 keV | 2.73 × 10-16 eV |
| Ne-19 | — | 17.22 s | Electron capture / beta-plus decay (100%) | 1,752.05 keV | 7,567.34 keV | 2.65 × 10-17 eV |
| Ne-23 | — | 37.25 s | Beta-minus decay (100%) | -5,154.05 keV | 7,955.26 keV | 1.22 × 10-17 eV |
| Ne-24 | — | 3.38 m | Beta-minus decay (100%) | -5,951.64 keV | 7,993.33 keV | 2.25 × 10-18 eV |
| Ne-25 | — | 602 ms | Beta-minus decay (100%) | -2,035.5 keV | 7,839.8 keV | 7.58 × 10-16 eV |
| Ne-26 | — | 197 ms | Beta-minus decay (100%), Beta-minus, neutron emission (0.13%) | 481.11 keV | 7,751.91 keV | 2.32 × 10-15 eV |
| Ne-27 | — | 31.5 ms | Beta-minus decay (100%), Beta-minus, neutron emission (2%) | 7,050.91 keV | 7,520.42 keV | 1.45 × 10-14 eV |
| Ne-28 | — | 20 ms | Beta-minus decay (100%), Beta-minus, neutron emission (12%), B-2N (3.7%) | 11,299.74 keV | 7,388.35 keV | 2.28 × 10-14 eV |
| Ne-29 | — | 15 ms | Beta-minus decay (100%), Beta-minus, neutron emission (28%), B-2N (4%) | 18,399.8 keV | 7,167.07 keV | 3.04 × 10-14 eV |
| Ne-30 | — | 7.3 ms | Beta-minus decay (100%), Beta-minus, neutron emission (13%), B-2N (8.9%) | 23,280.12 keV | 7,034.53 keV | 6.25 × 10-14 eV |
| Ne-31 | — | 3.4 ms | Beta-minus decay (100%), B-2N, B-3N | 31,181.59 keV | 6,813.09 keV | 1.34 × 10-13 eV |
| Ne-32 | — | 3.5 ms | Beta-minus decay (100%), Beta-minus, neutron emission | 36,999 keV | 6,671 keV | 1.30 × 10-13 eV |
| Ne-33 | — | 180 ns | Neutron emission | 46,130 keV | 6,436 keV | 2.53 × 10-9 eV |
| Ne-34 | — | 60 ns | Beta-minus decay, Beta-minus, neutron emission, B-2N | 52,842 keV | 6,287 keV | 7.60 × 10-9 eV |