Neon

Neon
Atomic number	10
Symbol	Ne
Group	18 (noble gases)
Boiling point	−246.0 °C
Electron configuration	[He] 2s2 2p6
Period	2
Main isotopes	20Ne, 21Ne, 22Ne
Phase STP	Gas
Block	p
Oxidation states	0
Wikidata	Q654

Neon is a chemical element with symbol Ne and atomic number 10. It is a noble gas (Group 18) in the second period of the periodic table. In its natural form, neon is a colorless, odorless monatomic gas that is chemically inert under ordinary conditions. At standard temperature and pressure (STP, 0 °C, 1 atm) neon exists as a gas. Its most common oxidation state is 0, meaning it does not normally form compounds. Neon’s name derives from the Greek word neos, meaning “new,” reflecting its discovery as a new component of air in 1898.

Neon is best known for its bright glowing discharge in gas tubes. When excited by an electric current or high voltage, neon atoms emit a characteristic orange-red light. This property has been exploited in neon signage and lighting. Neon also has important uses in lasers, in cryogenic refrigeration, and as a tracer in scientific applications. Its inertness makes it a useful buffer gas in some situations. Despite being inert, neon has multiple stable isotopes and distinctive emission spectra that are used in many areas of science.

Atomic Structure and Electron Configuration

A neutral neon atom has ten protons and ten electrons. The electrons are arranged in two shells: a filled n=1 shell (1s²) and a filled n=2 shell (2s²2p⁶). This closed-shell configuration He]2s²2p⁶) gives neon a stable, low-energy electronic structure. The filled valence shell means neon has an octet of electrons, analogous to the noble gas pattern, and no tendency to gain or lose electrons. In simple terms, neon’s valence shell electrons are tightly bound, making the atom energetically unwilling to form chemical bonds.

Because of this closed shell, neon’s atomic radius is quite small. The van der Waals radius of a neon atom is on the order of 150 pm (picometers) for interactions, and its single-atom “covalent” radius (a theoretical measure) is about 38 pm. In the periodic table trend, neon is much smaller than the heavier noble gases. Its first ionization energy (the energy to remove one electron) is very high: about 21.56 electronvolts (eV), or roughly 2 076 kJ/mol. This is among the highest of any element (second only to helium in its period), reflecting the strong hold of the nucleus on its electrons. The second ionization energy (removing a second electron) is even higher (around 40.96 eV), and removing all valence electrons requires extremely large energies, which means neon is extremely resistant to becoming ionized or forming cations.

Neon’s electronegativity is undefined in the usual sense because it virtually never forms compounds; it has almost no tendency to attract electrons. In practice, neon is considered non-metallic and so unreactive that simple electronegativity scales do not provide a meaningful value.

Periodically, neon occupies Group 18 (the noble gases) and Period 2. It follows helium, and its properties reflect the periodic trends of noble gases: small atomic radius, very high ionization energy, and negligible electron affinity (adding an electron is highly unfavorable). Its lack of stable chemical interactions is the hallmark of noble gas periodic behavior, with neon being more inert than argon and heavier noble gases but slightly less inert than helium.

Isotopes and Nuclear Properties

Neon has three stable isotopes found in nature: ^20Ne, ^21Ne, and ^22Ne. These differ in the number of neutrons (10, 11, and 12 neutrons, respectively). By natural abundance (in Earth’s atmosphere), ^20Ne makes up about 90.5%, ^22Ne about 9.3%, and the rare ^21Ne about 0.3% of neon atoms. All three have even numbers of protons and neutrons except ^21Ne, making ^20Ne and ^22Ne have spin 0 (nuclear spin 0) and ^21Ne have a nuclear spin of 3/2 (nonzero), which is of interest in some nuclear magnetic resonance studies.

There are no long-lived radioactive isotopes of neon under normal conditions. However, several radioactive isotopes have been produced artificially in nuclear reactors or particle accelerators, such as ^23Ne (with a half-life of about 37 seconds) and ^24Ne. These decay by beta emission or positron emission, but their half-lives are short enough that none are practically encountered outside laboratories.

In geoscience and cosmochemistry, neon isotopes serve as tracers. For example, the ratios of neon isotopes in air or meteorites contain information about early solar system processes and cosmic-ray exposure ages. Trapped neon in minerals or noble gas analyses can reveal information about the origin and history of planetary materials. ^21Ne in particular can accumulate from cosmic ray spallation and is used in dating meteorites or terrestrial exposure ages.

Allotropes and Compounds

Neon has no known allotropes because it exists only as individual atoms (monatomic gas). At very low temperatures under pressure, neon can condense into a solid (or liquid), but it does so in a simple face-centered cubic (fcc) crystal structure—there is no different bonding arrangement as in carbon (which has diamond, graphite, etc.). Solid neon, like solid helium or argon, is a soft, transparent crystal with weak van der Waals forces holding the atoms in place.

Neon compounds are essentially nonexistent under normal conditions. Unlike its heavier noble-gas cousins (like xenon, which forms fluorides or oxides), neon does not form stable chemical bonds at ambient pressure and temperature. Its highest occupied electronic shell is filled and at low energy, so it lacks both the tendency to gain an extra electron (very low electron affinity) and to share or lose electrons. The only “compounds” involving neon are by extraordinary methods. For example, extremely low-temperature matrices or high pressures can trap neon atoms in clathrate structures or interstitial sites, but these are physical encapsulations, not chemical bonds. There have been highly specialized laboratory experiments (for instance, involving boron-cyanide clusters or super-intense pressures) hinting at temporary neon-containing complexes, but these are not stable molecules one can bottle or handle; they exist only under very unusual conditions.

The practical upshot is that neon is chemically inert – it does not form molecules like hydrates, fluorides, oxides, or any normal compounds at room conditions. It does, however, dissolve up to a small extent in certain solvents (much like helium and other gases) or be physically trapped. For example, neon can form a hydrate with ice under very cold, high-pressure conditions, meaning a crystal of water encloses neon atoms in its cavities – but only at low temperatures near liquid nitrogen temperatures or below. These hydrates are again held by intermolecular forces, not by neon reacting, illustrating neon’s lack of ordinary bonding chemistry.

Physical Properties

Neon is a monatomic gas at room temperature that is colorless and odorless. It is lighter than air (molecular weight about 20.18 g/mol) and has a comparatively low density of about 0.9 kg/m³ at 0 °C and 1 atm (air is about 1.29 kg/m³). Neon’s gas is transparent and does not absorb visible light; its refractive index is very close to that of vacuum (about 1.00004). Under an electric discharge, neon atoms emit bright light, so discharge tubes filled with neon glow in characteristic colors (usually bright orange-red in glow-discharge).

Neon liquefies at very low temperatures. Its melting point is about 24.56 K (−248.59 °C) and its boiling point around 27.07 K (−246.08 °C) at 1 atmosphere. In other units, the triple point (solid-liquid-gas equilibrium) is at about 24.56 K and 0.43 atm, and the critical point occurs near 44.4 K and 26.2 atm. By volume, liquid neon is roughly 1/600th the volume of its gas at STP (reflecting the condensation of the gas). The density of liquid neon at its boiling point is about 1.206 g/cm³ (1206 kg/m³). Solid neon (formed by freezing the liquid at ~1 atm) has a density around 1.444 g/cm³ at the triple point. All solid and liquid phases are colorless and transparent to visible light.

Neon’s thermal properties: As a noble gas, it has a relatively high specific heat for a gas (on the order of 0.9 J/g·K at constant pressure) because it is monatomic (monatomic gases have heat capacity ~3/2 R per mole). Its thermal conductivity is moderate – about 0.049 W/(m·K) at 25 °C – roughly twice that of air. Neon’s sound speed is higher than air’s (because of its low molar mass); at 0 °C it is about 435 m/s (air is ~331 m/s).

Electrically, gaseous neon is an excellent insulator at low fields but will conduct via a plasma discharge at sufficiently high electric fields. Neon-glow discharge tubes require lower voltage than some other rare gases; typical breakdown (similar to neon bulb ignition) might require on the order of a few hundred volts at low pressure. In physical applications, neon is sometimes used as a neon buffer gas in vacuum systems or excitation lamps (glow lamps) because of its stable handling and distinctive glow.

Spectroscopically, neon has many notable lines in its emission spectrum. The strongest visible spectral lines are in the red-orange region, which is why neon glow lamps look orange-red. Notable lines include wavelengths around 585.2 nm (yellow), 640.2 nm (orange-red), 614.3 nm, 703 nm, and others. These lines result from excited neon atoms relaxing to lower energy levels. Neon has fewer lines in the blue/green region, which is why the predominant light is yellow-red. The famous 632.8 nm line, however, comes from the neon component in Helium-Neon (He–Ne) lasers; helium and neon in the laser mix produce a strong neon emission at 632.8 nm (red). Neon’s UV lines are used as calibration references in spectroscopy. Because its lines are sharp and well-known, neon discharge lamps are often used to calibrate spectrometers for visible light.

Finally, neon’s refractive index, refractivity, and optical properties are well known: it is only slightly refractive for light (index ~1.00004) and transparent in visible wavelengths. Neon’s solid and liquid forms do not have multiple crystal phases under ambient pressure; the stable structure is face-centered cubic (fcc) at low temperatures. Neon does not exhibit magnetism: it is diamagnetic (like other noble gases) and has no magnetic ordering in any form, owing to all paired electrons.

Chemical Reactivity and Trends

Neon is at the far extreme of chemical inertness. In chemical reactivity, it is placed at the bottom of the reactivity scale: it does not react with water, acids, or bases; it does not corrode or oxidize; and it is unaffected by strong reducing or oxidizing agents under normal conditions.

As a noble gas, neon does not form typical chemical bonds, so it has no behavior as an acid or base in the Brønsted–Lowry or Lewis sense. It does not dissolve significantly in water or most organic solvents (its solubility in water at 20 °C is very low, on the order of 10^-5 mol/mol). When present around reactive metals or chemicals, neon simply remains as separate atoms. It will not displace hydrogen from water or any source, nor will it oxidize or reduce any compound. In a fire or high-temperature environment, neon will not burn or shatter chemically; it will remain as neon atoms or a neon plasma if sufficiently energized.

Neon’s chemical inertness arises from its filled electron shell. Removing an electron (ionization) costs over 2,000 kJ/mol, and adding an electron is energetically unfavorable (neon’s electron affinity is effectively zero in practical terms, meaning it will not accept an electron). Therefore, neon does not participate in redox reactions, and no stable neon cations or anions exist at room conditions. Even the formation of diatomic or polyatomic neon species (Ne₂, NeXe, etc.) is negligible; any van der Waals clusters of neon (like small frozen clusters) are held only by very weak dispersion forces and do not count as chemical bonds.

Neon also does not undergo hydrolysis or polymerization – there is simply no chemical pathway. Under extremely energetic conditions (stellar interiors, nuclear explosions, or corona discharges), neon atoms can be ionized or broken apart, but on Earth these conditions are not naturally encountered in chemistry. Even in flames (like neon-burner or extremely hot jets), neon does not react; it might become ionized to glow, but it remains neon.

In the context of corrosion or passivation, neon’s behavior is trivial – it does not deposit layers on metals nor protect them; it usually is not used for that purpose because gold or platinum do not need neon’s inertness (they are inert themselves). Neon-filled environments would prevent oxidation of metals only by excluding oxygen, but that is a generic inert gas effect, not a specific neon reaction.

In summary, neon plays no active role in chemical reaction series or acid-base chemistry. It occupies the bottom rung of the reactivity series (inert gases), comparable to helium. The only notable chemical “interaction” is its physical solubility or scavenging in some advanced materials (like certain porous solids can trap neon atoms), but these are end of the line – no classical chemical reactivity is available for neon under ambient conditions.

Occurrence and Production

Neon is relatively common in the cosmos but rare on Earth.

• Cosmic abundance: Neon is the fifth or sixth most abundant element in the Universe by mass fraction (after hydrogen, helium, oxygen, carbon, and nitrogen). It is produced in stars via alpha-capture nucleosynthesis (fusing carbon into neon, and neon into magnesium). In the universe and the solar system, neon is more abundant than many elements like iron or gold.

• Solar system: In the Sun and planets, neon is present mostly as a non-reactive gas. For example, the Sun’s atmosphere contains neon (often measured via spectral lines), comprising on the order of 10^-4 by number relative to hydrogen (so a few parts in ten thousand). On jovian planets or gas giants (Jupiter, Saturn), neon is mixed with hydrogen and helium in their atmospheres.

• Earth’s atmosphere: On Earth, neon is present in the atmosphere at about 18.2 parts per million (ppm) by volume (which is about 0.00182% of air by volume). This is determined from analyses of dry air composition. For comparison, argon is about 0.93% and helium only ~5.2 ppm. Oxygen and nitrogen dominate the rest. Because neon is inert, it is not consumed or produced in biological or chemical processes, so its atmospheric amount has remained relatively stable over geological time, aside from slow diffusion to space.

• Earth’s crust: Neon does not form minerals, so it is not found in rocks or ores. It may be trapped loosely in some minerals but at extremely low concentrations, essentially negligible. Any neon that might have been present in the early Earth largely escaped to the atmosphere or lost to space because its light mass means it can reach escape velocity under certain conditions.

• Industrial production: Commercially, all neon is obtained by fractional distillation of liquefied air. When air is cooled and compressed to be liquefied, its components (nitrogen, oxygen, argon, etc.) boil off at different temperatures. Neon (and helium) are boiled off early and concentrated in a small fraction. Specialized air separation units capture the neon-rich gas and then further distill it (often as a mix with the small amounts of helium and hydrogen also present) to purify neon. Because neon is only 0.0018% of air, very large volumes of air must be processed to get usable quantities of neon gas.

There are no natural “neon mines”; neon is a by-product of oxygen and nitrogen gas production. Major industrial gas companies operated large facilities to extract neon. Historically, notable producers included facilities in the U.S., Europe, Russia, and especially Ukraine. For example, plants in Donetsk and Odessa regions of Ukraine were known for neon production (supplying the semiconductor industry). In recent times, major gas suppliers like Air Liquide, Linde, Praxair, and others produce neon.

Because neon is used in high-tech applications (lasers and semiconductors), its supply chain is linked to these industries. For instance, in 2022 news reports mentioned potential neon shortages due to supply disruptions, since neon is critical in certain plasma lasers used for chip etching. However, worldwide neon output is relatively small (on the order of tens of millions of cubic meters per year, quite low compared to air or nitrogen). Its commercial price reflects its rarity, sometimes several hundred dollars per cubic meter of gas.

Applications and Technology

Despite its chemical inertness, neon has many important applications that exploit its physical properties:

• Lighting and Signage: The most iconic use of neon is in neon lamps and neon signs. Low-pressure gas-discharge tubes filled with neon produce a bright orange-red light when a high voltage is applied. This is seen in decorative signs, rainbows of colors (by using other gases or fluorescent coatings), and advertising signage. Neon lighting was pioneered in the early 20th century by Georges Claude, and “neon signs” became synonymous with bright city nightlife. Modern neon lamps include indicators (small neon bulbs), gas-discharge lamps, and signs. True neon (single neon-filled lamps) specifically give mostly red/orange light; other colors are typically from mixing argon or other gases, but the term “neon lamp” is used generically for any such discharge lamp. Neon lamp technology is mostly replaced by LEDs now in new installations, but it remains valued for its distinct warm glow.

• Lasers: Neon plays a crucial role in the helium-neon laser. In these lasers, a mixture of helium and neon gas is excited by an electric discharge. The helium atoms transfer energy to neon atoms, which then lase. The most famous output is the 632.8 nm red laser line used in laboratories and alignment devices. Helium-neon lasers are common, low-power gas lasers (milliwatt range) used in teaching, holography, barcode scanners, and early survey instruments. The neon’s spectral lines in the gas determine the laser wavelength (so different isotopes or pressures can shift or allow other weaker lines, but 632.8 nm is the dominant line). Without neon, this type of laser would not work. Neon is not used by itself in practical lasers because population inversion is hard to achieve in pure neon without helium as a buffer/exciter.

• Cryogenics and Refrigeration: Liquid neon has special properties that make it useful in cryogenics. Its boiling point (27 K) is much higher than liquid helium (4 K) and slightly higher than hydrogen (20 K), making it suitable for intermediate-temperature refrigeration. Liquid neon has a very high volumetric cryocapacity: it can absorb a lot of heat per volume when it vaporizes, more than liquid helium or hydrogen. In practice, neon cryostats are used in scientific research (space instruments, infrared detectors, certain superconducting magnets) when temperatures around 25–30 K are needed. Because neon is inert and has no magnetic transitions, it causes no problems like helium’s superfluid leaks. It is more expensive than other cryogens, but in closed-cycle systems, it can be recycled. One famous example: NASA selected liquid neon as the coolant for the James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) instead of liquid helium, because neon provided stable cooling at needed temperatures for a long mission. On Earth, liquid neon can also be used in cold traps and cryogenic pumping systems. Its hazard is similar to other cryogens (risk of cold burns or asphyxiation) but it’s chemically safe and non-flammable.

• Electronics and Semiconductor Industry: Apart from lasers, neon gas and neon mixtures are sometimes used in specialized discharge tubes and etching processes. For example, neon is used as a buffer or in some gas lasers for lithography. In the semiconductor industry, high-purity neon is needed for certain lithography lasers (e.g. argon fluoride (ArF) lasers sometimes use neon as a diluent gas). Demand for high-purity neon surged when new chip factories came online, and disruptions in neon supply can affect chip production.

• Metrology and Research: Neon’s spectral lines are used as wavelength standards in spectrometers. Neon glow lamps may be employed as calibration sources because the wavelengths of neon emission lines are very precisely known. Neon’s inert nature also makes it handy as a tracer or sentinel gas in lab settings: for example, neon can be used to detect leaks or to calibrate instruments that measure trace gas flows, since it doesn’t react and is easy to detect with mass spectrometry.

• General Inert Atmosphere: While krypton or argon are more common, neon can serve as an inert gas purge in some specialized circumstances (such as in certain vacuum tubes or display technologies). Its low refractive index and non-fluorescing property (unless excited) make it useful in some optical or electrical insulation roles. However, its rarity and cost mean it is used only where its unique properties are required.

• Neon in Ultrasound and Other Niche Areas: Neon has been used to fill some bubble chamber detectors and was historically used as a component in neon signs for silent gas lasers. In medical imaging, helium-neon lasers were used for low-power therapy (though neon gas itself is not used in medicine). Neon can also be used in high-voltage indicators and some types of discharge lamps (similar to neon signs).

Overall, neon’s major roles are in lighting (especially the classic neon sign industry) and in applications that exploit its spectral or cryogenic properties. Its inertness and abundance (relative) in atmosphere make it readily available to technicians with the proper cryogenic equipment.

Biology, Environmental, and Safety Aspects

Neon has virtually no biological role in organisms. It is not known to be essential, toxic, or to interact with biological systems chemically. Because neon is chemically inert and poorly soluble in water, it does not dissolve significantly in blood or tissues. If inhaled, neon will displace oxygen in the lungs (since it is denser than air), and breathing pure neon leads to asphyxiation by oxygen deprivation, just as breathing pure nitrogen or helium would – but neon itself is not metabolized or toxic. There are no studies showing any metabolic uptake or adverse biochemical effect of neon; it simply behaves like a neutral inert gas in the body.

At high ambient pressures (as in deep diving conditions), neon could act as an inert gas that dissolves in tissues and might cause inert gas narcosis (a state of intoxication caused by any inert gas under pressure, typically more pronounced for heavier gases like argon or xenon). However, neon’s practical use in diving is nil, and helium or nitrogen are far more relevant. There is a rare use of helium-neon gas mixtures in some dive gases to mitigate nitrogen narcosis, but neon is not used for this.

Environmentally, neon is benign. It does not contribute to air pollution or climate change because it is inert and present at trace levels everywhere. It is not an ozone-depleting substance or greenhouse gas (it does not absorb infrared radiation significantly). When neon escapes to the atmosphere, it stays in the atmosphere or eventually escapes to space (lighter noble gases do this slowly over geologic time; it is part of why Earth’s atmosphere lost a lot of its primordial neon). On Earth’s surface, neon is not recycled by any biological or chemical cycle, so its atmospheric concentration changes only by physical processes.

Safety considerations for neon are mostly physical rather than chemical. Neon gas is colorless and odorless, so leaks in enclosed spaces can create an asphyxiation hazard similar to nitrogen or argon. A person in a small room with only neon might quickly suffocate without realizing it. Therefore, proper ventilation is essential where large volumes of neon gas are used (such as in gas handling facilities). Because neon is inert and non-flammable, it does not pose a fire or explosion hazard under normal conditions: it cannot aid combustion or explode, unlike oxygen or some flammable gases.

Liquid neon, being cryogenic (~27 K), poses a cold hazard. Contact with liquid neon or supercold gas can cause severe frostbite or cold burns. Pressurized cryogenic containers of neon must be handled with care. Additionally, if liquid neon boils off, it can displace oxygen in an enclosed space (like liquid nitrogen or helium) and cause suffocation risk. On the other hand, neon’s lack of chemical reactivity means it does not form peroxide hazards or react violently with moisture or other chemicals.

If neon is present in small systems (e.g. sealed glow lamps), the typical safety issues are the high-voltage ignition systems (shock hazard) rather than the neon itself. In summary, for occupational hazards, neon requires the same precautions as other inert industrial gases: monitor oxygen levels in enclosed spaces, avoid cryogenic burns, and handle high-pressure cylinders carefully. There are no specific exposure limits for neon because it’s not toxic; regulatory guidance would focus on oxygen displacement and cryogenic safety.

History and Etymology

Neon was discovered in 1898 by Scottish chemist Sir William Ramsay and English chemist Morris Travers. While analyzing liquid air (following the discovery of argon), Ramsay had identified krypton and xenon earlier that year. In the process of slowly evaporating liquid air, a new gas fraction that glowed with an intense red-orange light under a spark led to the discovery of neon. Ramsay and Travers announced the discovery of neon (and krypton, xenon) on June 7, 1898, and the name “neon” was announced on October 1898. It is derived from the Greek neos (“new”), reflecting that it was a newly identified element.

The symbol Ne comes from the first two letters of “neon.” The element’s full Latin/English name “neon” appeared first in a 1898 lecture abstract. In 1903, Ramsay received the Nobel Prize in Chemistry (partly for this discovery and separation of noble gases).

Just a few years after its discovery, neon began to find a public place. In 1910, French engineer Georges Claude demonstrated the first neon tube (neon lamp) in Paris. He filled glass tubes with neon gas and used electrodes to excite them; the vivid glowing tubes amazed audiences, and he soon patented the neon sign. The first commercial neon sign went up in Paris around 1912. Neon lighting spread worldwide in the early 20th century as a spectacular commercial lighting technology – especially in advertising. The era of neon signs is a cultural icon of mid-century cities (like Las Vegas, New York) and cinema. Technological advances have since led to fluorescent and LED lights, but true neon signs remain prized for certain artistic and aesthetic uses.

The first laser, built in 1960, was a helium–neon gas laser (invented by Ali Javan, William Bennett, and Donald Herriott). This scientific breakthrough immediately put neon into a critical role in laser research. For decades, Helium-Neon lasers were the standard red lasers in laboratories and industry.

Neon has also figured in scientific milestones. For example, neon isotopes on the Moon and in meteorites have been studied to learn about solar-wind composition and early solar system. Neon gas was also used in one of the first particle detectors (the bubble chamber). Its usage in these contexts underscores neon’s utility in physics and cosmochemistry.

Etymologically, the root neon appears in words meaning “new” (e.g., neophyte, neonate). Its adoption in physics language underscores the fresh discovery of an apparently inert, new component of air.

In summary, neon’s history is that of a scientifically fascinating element that quickly found practical use. Discovered at the turn of the 20th century in winning the puzzle of Earth’s atmosphere composition, neon became both a laboratory standard (spectral lines, lasers) and a popular icon (neon signs) of the modern industrial age.

Data Table

Property	Value / Description
Symbol	Ne
Atomic Number	10
Atomic Weight	20.1797 u (approximately)
Classification	Noble gas (Group 18, Period 2, p-block)
Electron Configuration	[He] 2s² 2p⁶ (10 electrons total)
Common Oxidation State	0 (no stable compounds)
Stable Isotopes	^20Ne (~90.5%), ^21Ne (~0.3%, spin 3/2), ^22Ne (~9.3%)
Phase at STP (0 °C, 1 atm)	Colorless gas
Density (gas, STP)	~0.9 kg/m³ (0°C, 1 atm)
Melting Point	~24.56 K (−248.6 °C)
Boiling Point	~27.07 K (−246.1 °C)
Triple Point	24.5561 K and 0.43 atm
Critical Point	44.4 K and 26.2 atm
Crystal Structure	Solid: face-centered cubic (fcc) at low temperature
Thermal Conductivity	~0.049 W/(m·K) (at 298 K)
Specific Heat (gas)	~0.9 J/(g·K) (constant pressure, 300 K)
First Ionization Energy	21.56 eV (about 2 076 kJ/mol)
Electron Affinity	~0 (negligible; neon does not form stable anions)
Electronegativity	Not defined (neon does not bond)
Van der Waals Radius	~154 pm
Atomic/Van der Waals Radii	Atomic radius ~38 pm (calculated)
Abundance (Universe)	~1000–1200 ppm by mass (in solar system)
Abundance (Earth’s atm.)	~18.2 ppm by volume (dry air)
Discovery	1898 by Sir William Ramsay and Morris Travers (liquid air separation)
Named After	Greek neos (new)