- History
- The cradle of argon
- Discovery
- Neon lights
- Physical and chemical properties
- - Appearance
- - Molar mass
- - Atomic number (Z)
- - Melting point
- - Boiling point
- - Density
- - Vapor density
- - Vapor pressure
- - Heat of fusion
- - Heat of vaporization
- - Molar heat capacity
- - Ionization energies
- - oxidation number
- - Reactivity
- Compounds
- Structure and electronic configuration
- Interaction interactions
- Liquid and glass
- Where to find and obtaining
- Supernovae and icy environments
- Air liquefaction
- Isotopes
- Risks
- Applications
- illumination
- Electronic industry
- Lasers
- Clathrate
- References
The neon is a chemical element that is represented by the symbol Ne. It is a noble gas whose name in Greek means new, a quality that it was able to sustain for decades not only because of the sparkle of its discovery, but also because it adorned cities with its light as they developed their modernization.
We have all ever heard of neon lights, which actually correspond to nothing more than red-orange; unless they are mixed with other gases or additives. Nowadays they have a strange air compared to the recent lighting systems; however, neon is much more than just a stunning modern light source.
Dragon made of tubes filled with neon and other gases that, when receiving an electric current, ionize and emit characteristic lights and colors. Source: AndrewKeenanRichardson.
This gas, which consists practically of Ne atoms, indifferent to each other, represents the most inert and noble substance of all; It is the most inert element in the periodic table, and currently and formally a stable enough compound is not known. It is even more inert than helium itself, but also more expensive.
The high cost of neon is due to the fact that it is not extracted from the subsoil, as happens with helium, but from the liquefaction and cryogenic distillation of the air; even when it is present in the atmosphere in sufficient abundance to produce a huge volume of neon.
It is easier to extract helium from natural gas reserves than to liquefy air and extract neon from it. In addition, its abundance is less than that of helium, both inside and outside the Earth. In the Universe, neon is found in novae and supernovae, as well as in regions frozen enough to prevent it from escaping.
In its liquid form, it is a much more effective refrigerant than liquid helium and hydrogen. Likewise, it is an element present in the electronics industry with regard to lasers and equipment that detect radiation.
History
The cradle of argon
The history of neon is closely related to that of the rest of the gases that make up the air and their discoveries. The English chemist Sir William Ramsay, together with his mentor John William Strutt (Lord Rayleigh), decided in 1894 to study the composition of air through chemical reactions.
Using a sample of air, they managed to deoxygenate and denitrogenize it, obtaining and discovering the noble gas argon. His scientific passion also led him to the discovery of helium, after dissolving the mineral cleveite in an acid medium and collecting characterizing the released gas.
At the time, Ramsay suspected that there was a chemical element located between helium and argon, dedicating unsuccessful attempts to find them in mineral samples. Until finally he considered that argon should be “hidden” other gases less abundant in the air.
Thus, the experiments that led to the discovery of neon began with condensed argon.
Discovery
In his work, Ramsay, assisted by his colleague Morris W. Travers, began with a highly purified and liquefied sample of argon, which he subsequently subjected to a kind of fractional and cryogenic distillation. Thus, in 1898 and at University College London, both English chemists managed to identify and isolate three new gases: neon, krypton and xenon.
The first of them was neon, which he glimpsed when they collected it in a glass tube where they applied an electric shock; its intense red-orange light was even more striking than the colors of krypton and xenon.
It was in this way that Ramsay gave this gas the name 'neon', which in Greek means 'new'; a new element appeared from argon. Shortly after, in 1904 and thanks to this work, he and Travers received the Nobel Prize in chemistry.
Neon lights
Ramsay then had little to do with the revolutionary applications of neon as far as lighting is concerned. In 1902, the electrical engineer and inventor, Georges Claude, together with Paul Delorme, formed the L'Air Liquide company, dedicated to selling liquefied gases to industries and which soon saw the luminous potential of neon.
Claude, inspired by the inventions of Thomas Edison and Daniel McFarlan Moore, built the first tubes filled with neon, signing a patent in 1910. He sold his product practically under the following premise: neon lights are reserved for cities and monuments because they are very dazzling and attractive.
Since then, the rest of the history of neon up to the present goes hand in hand with the appearance of new technologies; as well as the need for cryogenic systems that can use it as a cooling liquid.
Physical and chemical properties
- Appearance
Glass vial or vial with neon excited by an electric discharge. Source: Hi-Res Images of Chemical Elements
Neon is a colorless, odorless, tasteless gas. However, when an electrical discharge is applied, its atoms are ionized or excited, emitting photons of energy that enter the visible spectrum as a reddish-orange flash (top image).
So the neon lights are red. The higher the gas pressure, the higher the electricity required and the reddish glow obtained. These lights illuminating the alleys or the facades of the shops are very common, especially in cold climates; since, the reddish intensity is such that it can penetrate the mist from considerable distances.
- Molar mass
20.1797 g / mol.
- Atomic number (Z)
10.
- Melting point
-248.59 ° C.
- Boiling point
-246.046 ° C.
- Density
-Under normal conditions: 0.9002 g / L.
-From the liquid, just at the boiling point: 1.207 g / mL.
- Vapor density
0.6964 (relative to air = 1). In other words, air is 1.4 times denser than neon. Then a balloon inflated with neon will rise into the air; although less quickly compared to one inflated with helium.
- Vapor pressure
0.9869 atm at 27 K (-246.15 ° C). Note that at such a low temperature neon already exerts a pressure comparable to atmospheric.
- Heat of fusion
0.335 kJ / mol.
- Heat of vaporization
1.71 kJ / mol.
- Molar heat capacity
20.79 J / (mol · K).
- Ionization energies
-First: 2080.7 kJ / mol (Ne + gaseous).
-Second: 3952.3 kJ / mol (Ne 2+ gas).
-Third: 6122 kJ / mol (Ne 3+ gaseous).
The ionization energies for neon are particularly high. This is due to the difficulty of removing one of its valence electrons from its very small atom (compared to the other elements of its same period).
- oxidation number
The only probable and theoretical number or oxidation state for neon is 0; that is, in its hypothetical compounds it does not gain or lose electrons, but rather interacts as a neutral atom (Ne 0).
This is due to its null reactivity as a noble gas, which does not allow it to gain electrons due to the lack of an energetically available orbital; and neither can it be lost by having positive oxidation numbers, due to the difficulty of overcoming the effective nuclear charge of its ten protons.
- Reactivity
The aforementioned explains why a noble gas is not very reactive. However, among all the noble gases and chemical elements, neon is the owner of the true crown of nobility; It does not admit electrons in any way or from anyone, and it cannot share its own because its nucleus prevents it and, therefore, does not form covalent bonds.
Neon is less reactive (more noble) than helium because, although its atomic radius is larger, the effective nuclear charge of its ten protons exceeds that of the two protons in the helium nucleus.
As one descends through group 18, this force decreases because the atomic radius increases considerably; And that's why the other noble gases (especially xenon and krypton) can form compounds.
Compounds
To date, no remotely stable compound of neon is known. However, the existence of polyatomic cations such as: +, WNe 3+, RhNe 2+, MoNe 2+, + and + has been verified by means of optical and mass spectrometry studies.
Likewise, mention can be made of their Van der Walls compounds, in which although there are no covalent bonds (at least not formally), the non-covalent interactions allow them to remain cohesive under rigorous conditions.
Some such Van der Walls compounds for neon are, for example: Ne 3 (trimer), I 2 Ne 2, NeNiCO, NeAuF, LiNe, (N 2) 6 Ne 7, NeC 20 H 20 (endohedral fullerene complex), etc. And also, it should be noted that organic molecules can also "rub shoulders" with this gas under very special conditions.
The detail of all these compounds is that they are not stable; moreover, most originate in the midst of a very strong electric field, where gaseous metal atoms are excited in the company of neon.
Even with a covalent (or ionic) bond, some chemists don't bother to think of them as true compounds; and therefore, neon continues to be a noble and inert element seen from all "normal" sides.
Structure and electronic configuration
Interaction interactions
The neon atom could be visualized as an almost compact sphere due to its small size, and to the great effective nuclear charge of its ten electrons, eight of which are of valence, according to their electronic configuration:
1s 2 2s 2 2p 6 or 2s 2 2p 6
Thus, the Ne atom interacts with its environment using its 2s and 2p orbitals. However, they are completely filled with electrons, complying with the famous valence octet.
It cannot gain more electrons because the 3s orbital is not energetically available; Besides, it cannot lose them either because of their small atomic radius and the "narrow" distance separates them from the ten protons in the nucleus. Therefore, this Ne atom or sphere is very stable, unable to form chemical bonds with practically any element.
It is these Ne atoms that define the gas phase. Being very small, its electronic cloud is homogeneous and compact, difficult to polarize and, therefore, to establish instantaneous dipole moments that induce others in neighboring atoms; that is, the scattering forces between the Ne atoms is very weak.
Liquid and glass
That is why the temperature must drop to -246 ºC so that neon can go from a gaseous state to a liquid.
Once at this temperature, the Ne atoms are close enough for dispersion forces to bind them together in a liquid; that although apparently it is not as impressive as the quantum fluid of liquid helium and its superfluidity, it has a cooling power 40 times greater than this.
This means that a liquid neon cooling system is 40 times more efficient than a liquid helium one; cools faster and maintains temperature for longer.
The reason could be due to the fact that, even with Ne atoms being heavier than He, the former separate and disperse more easily (heat up) than the latter; but their interactions are so weak during their collisions or encounters, that they again slow down (cool down) rapidly.
As the temperature drops even further, to -248 ° C, the dispersion forces become stronger and more directional, now capable of ordering He atoms to crystallize into a face-centered cubic (fcc) crystal. This helium fcc crystal is stable under all pressures.
Where to find and obtaining
Supernovae and icy environments
In the formation of a supernova, neon jets are scattered, which end up composing these stellar clouds and traveling to other regions of the Universe. Source: Pxhere.
Neon is the fifth most abundant chemical element in the entire Universe. Due to its lack of reactivity, high vapor pressure, and light mass, it escapes from the Earth's atmosphere (although to a lesser degree than helium), and little dissolves in the seas. That is why here, in the Earth's air, it barely has a concentration of 18.2 ppm by volume.
For said concentration of neon to increase, it is necessary to lower the temperature to the neighborhood of absolute zero; conditions only possible in the Cosmos, and to a lesser degree, in the icy atmospheres of some gas giants like Jupiter, on the rocky surfaces of meteorites, or in the exosphere of the Moon.
Its greatest concentration, however, lies in the novae or supernovae distributed throughout the Universe; as well as in the stars from which they originate, more voluminous than our sun, inside which neon atoms are produced as a result of a nucleosynthesis between carbon and oxygen.
Air liquefaction
Although its concentration is only 18.2 ppm in our air, it is enough to get a few liters of neon from any home space.
Thus, to produce it, it is necessary to subject the air to liquefaction and then carry out a cryogenic fractional distillation. In this way, its atoms can be separated from the liquid phase composed of liquid oxygen and nitrogen.
Isotopes
Neon's most stable isotope is 20 Ne, with an abundance of 90.48%. It also has two other isotopes that are also stable, but less abundant: 21 Ne (0.27%) and 22 Ne (9.25%). The remainder are radioisotopes, and at the moment fifteen of them are known in total (15-19 Ne and 23-32 Ne).
Risks
Neon is a harmless gas from almost every possible aspect. Due to its null chemical reactivity, it does not intervene at all with any metabolic process, and just as it enters the body, it leaves it without being assimilated. It therefore has no immediate pharmacological effect; although, it has been associated with possible anesthetic effects.
That is why if there is a neon leak, it is not a worrying alarm. However, if the concentration of its atoms in the air is very high, it can displace the oxygen molecules we breathe, which ends up causing suffocation and a series of symptoms associated with it.
However, liquid neon could cause cold burns on contact, so it is not advisable to touch it directly. Also, if the pressure in your containers is very high, an abrupt fissure could be explosive; not by the presence of flames but by the force of the gas.
Neon does not represent a danger to the ecosystem either. Furthermore, its concentration in the air is very low and there is no problem in breathing it. And most importantly: it is not a flammable gas. Therefore, it will never burn no matter how high the temperatures are.
Applications
illumination
As mentioned, red neon lights are present in thousands of establishments. The reason is that only a low pressure of the gas is required (~ 1/100 atm) so that it can produce, at the electric discharge, its characteristic light, which has also been placed in advertisements of different kinds (advertising, signs of road, etc.).
Neon-filled tubes can be made of glass or plastic, and take on all kinds of shapes or forms.
Electronic industry
Neon is a very important gas in the electronics industry. It is used for the manufacture of fluorescent and heating lamps; devices that detect radiation or high voltages, television kinescopes, Geyser counters and ionization chambers.
Lasers
Together with helium, the Ne-He duo can be used for laser devices, which project a beam of reddish light.
Clathrate
While it is true that neon cannot form any compounds, it has been found that under high pressure (~ 0.4 GPa) its atoms are trapped within ice to form clathrate. In it, the Ne atoms are confined to a kind of channel limited by water molecules, and within which they can move along the crystal.
Although at the moment there are not many potential applications for this neon clathrate, it could in the future be an alternative for its storage; or simply serve as a model to deepen our understanding of these frozen materials. Perhaps, on some planets, neon is trapped in masses of ice.
References
- Shiver & Atkins. (2008). Inorganic chemistry. (Fourth edition). Mc Graw Hill.
- National Center for Biotechnology Information. (2019). Neon. PubChem Database. CID = 23987. Recovered from: pubchem.ncbi.nlm.nih.gov
- J. de Smedt, WH Keesom and HH Mooy. (1930). On the Crystal structure of Neon. Physical Laboratory at Leiden.
- Xiaohui Yu & col. (2014). Crystal structure and encapsulation dynamics of ice II-structured neon hydrate. Proceedings of the National Academy of Sciences 111 (29) 10456-10461; DOI: 10.1073 / pnas.1410690111
- Wikipedia. (2019). Neon. Recovered from: en.wikipedia.org
- Helmenstine, Anne Marie, Ph.D. (December 22, 2018). 10 Neon Facts - Chemical Element. Recovered from: thoughtco.com
- Dr. Doug Stewart. (2019). Neon Element Facts. Chemicool. Recovered from: chemicool.com
- Wikipedia. (2019). Neon compounds. Recovered from: en.wikipedia.org
- Nicola McDougal. (2019). The Element Neon: History, Facts & Uses. Study. Recovered from: study.com
- Jane E. Boyd & Joseph Rucker. (August 9, 2012). A Blaze of Crimson Light: The Story of Neon. Science History Institute. Recovered from: sciencehistory.org