Name: Neon
Symbol: Ne
Atomic Number: 10
Atomic Weight: 20.179700
Family: Noble Gases
CAS RN: 7440-01-9
Description: An inert colorless gas.
State (25C): Gas
Oxidation states: 0

Molar Volume: 16.8 cm3/mole
Valence Electrons: 2p6

Boiling Point: 27.246K, -245.904C, -410.6F
Melting Point:
24.703K, -248.447C, -415.205F
Electrons Energy Level: 2, 8
Isotopes: 13 + 3 Stable
Heat of Vaporization: 1.7326 kJ/mol
Heat of Fusion: 0.3317 kJ/mol
Density: 0.9 g/L @ 273K & 1atm
Specific Heat: 0.904 J/gK
Atomic Radius: 0.51
Ionic Radius: unknown
Electronegativity: N/A (Pauling); 4.84 (Allrod Rochow)
Neon (Greek meaning "new") was discovered in 1898 Scottish chemist William Ramsay and English chemist Morris Travers in London, England.

Neon is perhaps the best known noble gas because of its use in so-called "neon" lights (many of which actually contain other gases) and is relatively plentiful in the earth's atmosphere.   Neon is actually abundant on a universal scale: the fifth most abundant chemical element in the universe by mass, after hydrogen, helium, oxygen, and carbon.  Its relative rarity on Earth, like that of helium, is due to its relative lightness and chemical inertness, both properties keeping it from being trapped in the condensing gas and dust clouds of the formation of smaller and warmer solid planets like Earth.   Mass abundance in the universe is about 1 part in 750 and in the Sun and presumably in the proto-solar system nebula, about 1 part in 600. The Galileo spacecraft atmospheric entry probe found that even in the upper atmosphere of Jupiter, neon is reduced by about a factor of 10, to 1 part in 6,000 by mass.  This may indicate that even the ice-planetesmals which brought neon into Jupiter from the outer solar system, formed in a region which was too warm for them to have kept their neon (abundances of heavier inert gases on Jupiter are several times that found in the Sun).  No stable compounds of neon are known to date. The gas is extracted from air by liquefaction.

Neon is the second-lightest noble gas, glows reddish-orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid helium and three times that of liquid hydrogen (on a per unit volume basis); it also contains a strong green line which is hidden, unless the visual components are dispersed by a spectroscope.  In most applications it is a less expensive refrigerant than helium.  Neon plasma has the most intense light discharge at normal voltages and currents of all the rare gases.   


1s2 2s2p6


The reddish-orange color that neon emits in neon lights is widely used to make advertising signs and is also used in long tubular strips in car modification. The word "neon" is also used generically for these types of lights even though many other gases are used to produce different colors of light. Other uses:

Neon is a monatomic gas at standard conditions.  Neon is rare on Earth, found in the Earth's atmosphere at 1 part in 65,000 (by volume) or 1 part in 83,000 by mass. It is industrially produced by cryogenic fractional distillation of liquefied air.

2s2 2p6


The ions, Ne+, (NeAr)+, (NeH)+, and (HeNe+), have been observed from optical and mass spectrometric research.  In addition, neon forms an unstable hydrate.


Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). 21Ne and 22Ne are nucleogenic and their variations are well understood. In contrast, 20Ne is not known to be nucleogenic and the causes of its variation in the Earth have have been hotly debated.  The principal nuclear reactions which generate neon isotope are neutron emission, alpha decay reactions on 24Mg and 25Mg, which produce 21Ne and 22Ne, respectively.   The alpha particles are derived from uranium-series decay chains, while the neutrons are mostly produced by secondary reactions from alpha particles. The net result yields a trend towards lower 20Ne/22Ne and higher 21Ne/22Ne ratios observed in uranium-rich rocks such as granites.  Isotopic analysis of exposed terrestrial rocks has demonstrated the cosmogenic production of 21Ne.   This isotope is generated by spallation reactions on magnesium, sodium, silicon, and aluminum.  By analyzing all three isotopes, the cosmogenic component can be resolved from magmatic neon and nucleogenic neon. This suggests that neon will be a useful tool in determining cosmic exposure ages of surficial rocks and meteorites. 

Similar to xenon, neon content observed in samples of volcanic gases are enriched in 20Ne, as well as nucleogenic 21Ne, relative to 22Ne content. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. The 20Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing solar neon.  Elevated 20Ne abundances are also found in diamonds, further suggesting a solar neon reservoir in the Earth.

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Isotope Atomic Mass Half-Life
Ne16 16.0258 122 keV
Ne17 17.0177 109.2ms
Ne18 18.0057 1672 ms
Ne19 19.0019 17.22 seconds
Ne20 19.9924 Stable
Ne21 20.9938 Stable
Ne22 21.9914 Stable
Ne23 22.9945 37.24 seconds
Ne24 23.9936 3.38 minutes
Ne25 24.9978 602 ms
Ne26 26.0005 197 ms
Ne27 27.0076 32 ms
Ne28 28.012 17 ms
Ne29 29.019 0.2 seconds
Ne30 30.024 >200 ns
Ne31 31.033  
Ne32 32.04 >200 ns

Neon was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, shortly after their discovery of the element krypton in 1898.  Like krypton, neon was discovered through the study of liquefied air. Although neon is the fourth most abundant element in the universe, only 0.0018% of the earth's atmosphere is neon.

The largest use for neon gas is in advertising signs. Neon is also used to make high voltage indicators and is combined with helium to make helium-neon lasers. Liquid neon is used as a cryogenic refrigerant. Neon is highly inert and forms no known compounds, although there is some evidence that it could form a compound with fluorine.

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Neon Data


Atomic Structure

Atomic Radius (): 0.51
Atomic Volume cm3/mol : 16.7cm3/mol
Covalent Radius: 0.71
Crystal Structure: Cubic face centered
Ionic Radius: unknown

Chemical Properties

Electrochemical Equivalents: unknown
Electron Work Function: unknown
Electronegativity: N/A (Pauling); 4.84 (Allrod Rochow)
Heat of Fusion: 0.3317 kJ/mol
Incompatibilities: unknown
First Ionization Potential: 21.564
Second Ionization Potential: 40.962
Third Ionization Potential: 63.45
Valence Electron Potential: unknown
Ionization Energy (eV): 21.565 eV

Physical Properties

Atomic Mass Average: 20.1797
Boiling Point: 27.246K, -245.904C, -410.6F
Melting Point: 24.703K, -248.447C, -415.205F
Heat of Vaporization: 1.7326 kJ/mol
Coefficient of Lineal Thermal Expansion/K-1: N/A
Electrical Conductivity: unknown
Thermal Conductivity: 0.000493 W/cmK
Density: 0.9 g/L @ 273K & 1atm
Enthalpy of Atomization: unknown
Enthalpy of Fusion: 0.33 kJ/mole
Enthalpy of Vaporization: 1.71 kJ/mole
Flammability Class: unknown
Molar Volume: 16.8 cm3/mole
Optical Refractive Index: 1.000067
Relative Gas Density (Air=1): unknown
Specific Heat: 0.904 J/gK
Vapor Pressure: unknown
Estimated Crustal Abundance: 510-3 milligrams per kilogram
Estimated Oceanic Abundance: 1.210-4 milligrams per liter

(Gr. neos, new) Discovered by Ramsay and Travers in 1898. Neon is a rare gaseous element present in the atmosphere to the extent of 1 part in 65,000 of air. It is obtained by liquefaction of air and separated from the other gases by fractional distillation. Natural neon is a mixture of three isotopes. Six other unstable isotopes are known. It is a very inert element; however, it is said to form a compound with fluorine. It is still questionable if true compounds of neon exist, but evidence is mounting in favor of their existence. The following ions are known from optical and mass spectrometric studies: Ne+, (NeAr)+, (NeH)+, and (HeNe+). Neon also forms an unstable hydrate. In a vacuum discharge tube, neon glows reddish orange. Of all the rare gases, the discharge of neon is the most intense at ordinary voltages and currents. Neon is used in making the common neon advertising signs, which account for its largest use. It is also used to make high-voltage indicators, lightning arrestors, wave meter tubes, and TV tubes. Neon and helium are used in making gas lasers. Liquid neon is now commercially available and is finding important application as an economical cryrogenic refrigerant. It has over 40 times more refrigerating capacity per unit volume than liquid helium and more than three times that of liquid hydrogen. It is compact, inert, and is less expensive than helium when it meets refrigeration requirements. Neon costs about $2.00/l.

Source: CRC Handbook of Chemistry and Physics, 1913-1995. David R. Lide, Editor in Chief. Author: C.R. Hammond