|Name , symbol , atomic number||Neon, Ne, 10|
|Element category||Noble gases|
|Group , period , block||18 , 2 , p|
|Mass fraction of the earth's envelope||0.005 ppm|
|Atomic mass||20, 1797 (6) et al|
|Covalent radius||58 pm|
|Van der Waals radius||154 pm|
|Electron configuration||[ He ] 2 s 2 2 p 6|
|1. Ionization energy||21st.564 540 (7) eV ≈ 2 080.66 kJ / mol|
|2. Ionization energy||40.96297 (4) eV ≈ 3 952.32 kJ / mol|
|3. Ionization energy||63.4233 (3) eV ≈ 6 119.42 kJ / mol|
|4. Ionization energy||97.1900 (25) eV ≈ 9 377.41 kJ / mol|
|5. Ionization energy||126.247 (12) eV ≈ 12 181 kJ / mol|
|Crystal structure||Cubic area-centered|
|density||0.900 kg m −3 at 273 K.|
|magnetism||diamagnetic ( Χ m = −3.8 10 −9 )|
|Melting point||24.56 K (−248.59 ° C)|
|boiling point||27.15 K (−246 ° C)|
|Molar volume||(solid) 13.23 · 10 −6 m 3 · mol −1|
|Heat of evaporation||1.9 kJ / mol|
|Heat of fusion||0.34 kJ mol −1|
|Speed of sound||435 m · s −1|
|Thermal conductivity||0.0491 W m −1 K −1|
|For other isotopes see list of isotopes|
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions .
In the periodic table it is in the 8th main group or the 18th IUPAC group and is therefore one of the noble gases . Like the other noble gases, it is a colorless, extremely inert, monatomic gas. In many properties, such as melting and boiling point or density , it stands between the lighter helium and the heavier argon .
In the universe Neon is one of the most common elements on Earth, however, it is relatively rare, because as with helium, much of the gas has escaped into space. It is mainly found in the earth's atmosphere , only small amounts are enclosed in rocks.
Like krypton and xenon , neon was discovered in 1898 by William Ramsay and Morris William Travers through fractional distillation of liquid air. The best-known applications are fluorescent tubes or neon lamps, in which neon is excited to glow by gas discharges in a typical orange-red color.
In 1894, Lord Rayleigh and William Ramsay discovered argon as the first noble gas . Ramsay isolated in 1895 and the previously only of the solar spectrum known helium from uranium ores . From the laws of the periodic table he recognized that between helium and argon there had to be another element with an atomic mass of about 20 u .
Therefore, from 1896 onwards, he first investigated various minerals and meteorites and the gases given off by them when heated or dissolved. Ramsay and his colleague Morris William Travers were unsuccessful, however, and helium and, less often, argon were found. The investigation of hot gases from Cauterets in France and from Iceland also yielded no results.
Eventually, they began examining 15 liters of crude argon isolated from liquid air and separating them by liquefaction and fractional distillation . The first element separated by this and detected in the flame spectrum was krypton ; on June 13, 1898, a lighter element was finally isolated from the lower-boiling fraction of crude argon. Ramsay and Travers called this neon , after the Greek νέος néos , German 'new' . A short time later they were able to extract another element, xenon , from the fraction containing krypton .
Neon, especially the isotope 20 Ne, is an important intermediate product in nucleosynthesis in stars, but is only formed when carbon is burned . During the burning of helium at around 200 · 10 6 K , 20 Ne is not formed due to the small capture cross-section of 16 O for α-particles; only the isotopes 21 Ne and 22 Ne can arise from the heavier 18 O. 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 24 Mg *. From this 20 Ne is formed by α-decay .
Due to the higher sensitivity of 20 Ne compared to 16 O to gamma radiation , this takes place before the actually expected reactions of the lighter oxygen nucleus. Oxygen burning takes place only after the neon burns , in which 16 O heavier elements such as silicon , phosphorus and sulfur are formed.
Neon is one of the most common elements in the universe , only hydrogen , helium, oxygen , carbon and nitrogen are more common. On the other hand, like helium, it is relatively rare on earth ; the total proportion of the earth's shell is around 0.005 ppm . Most of the neon is in the atmosphere, with an average content of 18.18 ppm it is the most common noble gas after argon. From the different distribution of the light and heavy isotopes of neon on the earth and the sun, it can be concluded that a large part of the neon has escaped from the atmosphere since the formation of the earth and that preferably the heavier isotopes 21 Ne and 22 Ne have remained.
Neon is also found in small quantities in the rocks of the earth. It was found in granite , basalt rocks , diamonds and volcanic gases . Due to different isotopic compositions, it is assumed that this neon has three different origins: Primordial neon, whose composition corresponds to that of the sun and which is enclosed in diamonds or in the earth's mantle without contact with the atmosphere; atmospheric neon and neon created by spallation reactions with cosmic rays .
On gas planets like Jupiter the neon cannot escape due to the high gravity , the isotopic composition therefore corresponds to that during the formation of the planet. As determined by the Galileo space probe , the ratio of 20 Ne to 22 Ne corresponds to that of the sun, which allows conclusions to be drawn about the formation conditions, such as the temperature, when the gas planets formed.
Extraction and presentation
Neon can be obtained as a by-product of air separation using the Linde process . After water , carbon dioxide , oxygen, the noble gases that boil at higher temperatures and most of the nitrogen have been separated off, a gas mixture remains that consists of 35% neon, as well as helium , hydrogen and about 50% nitrogen (both proportions ). This can be separated in different ways, so that in the end the pure gases neon and helium are obtained. One possibility is to separate the gases by condensation at different boiling points and by using the Joule-Thomson effect . After the hydrogen has been separated off via a catalytic reaction with added oxygen and the water has been removed, the nitrogen is first liquefied at 30 bar and 66 K and separated off. After the removal of the remaining nitrogen by adsorption on silica gel , a gas mixture of about 76% neon and 24% helium remains. This is first compressed to 180 bar at room temperature and then gradually cooled to 50 K. When expanding to 25 bar and then to 1.5 bar, the neon condenses, while helium remains gaseous. Fine separation is then carried out by rectification .
An alternative is adsorption. For this purpose, after the nitrogen has been separated off, the neon is adsorbed onto a carrier material at 5 bar and 67 K. This releases the neon again at 3 bar so that it can be separated from the helium. In order to achieve greater purity, the neon is adsorbed twice in succession.
Under normal conditions, neon is a monoatomic, colorless and odorless gas that condenses at 27 K (−246 ° C) and solidifies at 24.57 K (−248.59 ° C). It has the smallest temperature range of all elements in which it is liquid. Like the other noble gases apart from helium, neon crystallizes in a cubic close packing of spheres with the lattice parameter a = 443 pm .
With a density of 0.9 kg / m 3 at 0 ° C and 1013 hPa, neon is somewhat lighter than air, so it rises. In the phase diagram , the triple point is at 24.56 K and 43.37 kPa, the critical point at 44.4 K, 265.4 kPa and a critical density of 0.483 g / cm 3 .
Neon is poorly soluble in water; a maximum of 10.5 ml of neon can dissolve in one liter of water at 20 ° C.
Like other noble gases, neon shows a characteristic spectrum of lines during gas discharges . Since the lines in the visible spectral range are predominantly in the red to yellow range, the gas appears in a typical red color during a discharge.
As a typical noble gas, neon is extremely inert; as with helium, no compounds of the element are known to date. Even clathrates in which other noble gases are physically entrapped in other compounds are unknown. According to theoretical calculations, neon is the least reactive element. The calculated enthalpy of dissociation for compounds of the type NgBeO (Ng: noble gas) is lowest for the neon compound. It turned out that even the neon analogue of the only known helium compound, HHeF, which is stable according to calculations, should not be stable. Possible explanations for these results are the larger fluorine-hydrogen distances and thus weaker attractive forces in the HNe + ion compared to the helium species or repulsive p-π interactions in neon cations.
A total of 19 isotopes of neon between 15 Ne and 34 Ne are known. Of these, three, 20 Ne, 21 Ne and 22 Ne are stable and also occur in nature. With a share of 90.48%, 20 Ne is by far the most common. With a share of 0.27%, 21 Ne is the rarest on earth and 22 Ne occurs with a frequency of 9.25% in the natural isotope distribution on earth. All other isotopes have short half-lives of a maximum of 3.38 minutes at 24 Ne.
Due to the loss of neon into space and its formation in nuclear reactions, the ratio of 20 Ne / 22 Ne and 21 Ne / 22 Ne of neon, which is enclosed in rocks and has no contact with the atmosphere, is not always the same. Therefore, conclusions can be drawn about the formation from the isotope ratios. For example, in rocks in which neon was formed through spallation reactions , the content of 21 Ne is increased. Primordial neon, which was trapped in rocks and diamonds before a large part of the neon was lost, has a higher proportion of 20 Ne.
Like the other noble gases, neon has no biological significance due to its inertia and is also non-toxic. In higher concentrations, it has a suffocating effect by displacing the oxygen. At pressures of more than 110 bar it has a narcotic effect .
Due to the rarity and complicated production and the associated higher price compared to the similar argon, neon is only used in smaller quantities. Neon is the filling gas for fluorescent tubes and glow lamps , in which it is stimulated to glow in a typical orange-red color by gas discharges . Neon is also used as a filling gas in flash and stroboscope lamps.
Helium-neon lasers , in which a mixture of helium and neon is used, are among the more important lasers. The necessary population inversion of the laser is achieved by the excitation of the helium and the radiationless transition from electrons to neon. The stimulated emission occurs on neon at wavelengths of 632.8 nm (red) as well as 1152.3 nm and 3391 nm (infrared). Further laser transitions, for example in the green spectral range at 543.3 nm, are possible.
Neon can be used in a mixture with oxygen as breathing gas for diving at great depths. However, it is only rarely used because it has a higher price compared to similarly usable helium and also has a greater breathing resistance .
- P. Häussinger, R. Glatthaar, W. Rhode, H. Kick, C. Benkmann, J. Weber, H.-J. Wunschel, V. Stenke, E. Leicht, H. Stenger: Noble Gases. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH, Weinheim 2006; doi: 10.1002 / 14356007.a17_485 .
- Entry to neon. In: Römpp Online . Georg Thieme Verlag, accessed on June 19, 2014.
- AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , pp. 417-429.
- Harry H. Binder: Lexicon of the chemical elements. S. Hirzel Verlag, Stuttgart 1999, ISBN 3-7776-0736-3 .
- The values for the properties (info box) are taken from www.webelements.com (Neon) , unless otherwise stated .
- Michael E. Wieser, Tyler B. Coplen: Atomic weights of the elements (IUPAC Technical Report). In: Pure and Applied Chemistry . Volume 83, No. 2, 2011, pp. 359-396, doi: 10.1351 / PAC-REP-10-09-14 (free full text).
- IUPAC, Standard Atomic Weights Revised 2013 .
- entry on neon in Kramida, A., Ralchenko, Yu., Reader, J. and NIST ASD Team (2019): NIST Atomic Spectra Database (ver. 5.7.1) . Ed .: NIST , Gaithersburg, MD. doi : 10.18434 / T4W30F ( https://physics.nist.gov/asd ). Retrieved June 11, 2020.
- entry on neon at WebElements, https://www.webelements.com , accessed on June 11, 2020.
- Robert C. Weast (Ed.): CRC Handbook of Chemistry and Physics . CRC (Chemical Rubber Publishing Company), Boca Raton 1990, ISBN 0-8493-0470-9 , pp. E-129 to E-145. Values there are based on g / mol and given in cgs units. The value specified here is the SI value calculated from it, without a unit of measure.
- Yiming Zhang, Julian RG Evans, Shoufeng Yang: Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks. In: Journal of Chemical & Engineering Data. 56, 2011, pp. 328-337; doi: 10.1021 / je1011086 .
- David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Geophysics, Astronomy, and Acoustics, pp. 14-49. at 0 ° C.
- William Ramsay: The Rare Gases of the Atmosphere . Nobel Prize Speech, December 12, 1904.
- Patent application US1125476 System of illuminating by luminescent tubes. Registered October 8, 1911, published January 19, 1915, applicant: Georges Claude.
- LR Buchmann, CA Barnes: Nuclear reactions in stellar helium burning and later hydrostatic burning stages. In: Nuclear Physics A. 777, 2006, pp. 254-290; doi: 10.1016 / j.nuclphysa.2005.01.005 .
- SE Woosley, A. Heger: The evolution and explosion of massive stars. In: Rev. Mod. Phys. Volume 74, 2002, pp. 1015-1071, doi: 10.1103 / RevModPhys.74.1015 .
- David R. Williams: Earth Fact Sheet . NASA , Greenbelt, as of May 20, 2009.
- Alan P. Dickin: Radiogenic isotope geology. 2nd Edition. Cambridge University Press, 2005, ISBN 0-521-82316-1 , pp. 303-307.
- PR Mahaffy, HB Niemann, A. Alpert, SK Atreya, J. Demick, TM Donahue, DN Harpold, TC Owen: Noble gas abundance and isotope ratios in the atmosphere of Jupiter from the Galileo Probe Mass Spectrometer. In: J. Geophys. Res. Volume 105, 2000, pp. 15061-15071, doi: 10.1029 / 1999JE001224 .
- P. Häussinger, R. Glatthaar, W. Rhode, H. Kick, C. Benkmann, J. Weber, H.-J. Wunschel, V. Stenke, E. Leicht, H. Stenger: Noble Gases. In: Ullmann's Encyclopedia of Industrial Chemistry . Wiley-VCH, Weinheim 2006, doi: 10.1002 / 14356007.a17_485 .
- K. Schubert: A model for the crystal structures of the chemical elements. In: Acta Crystallographica. 30, 1974, pp. 193-204; doi: 10.1107 / S0567740874002469 .
- Entry on neon (phase change data). In: P. J. Linstrom, W. G. Mallard (Eds.): NIST Chemistry WebBook, NIST Standard Reference Database Number 69 . National Institute of Standards and Technology , Gaithersburg MD, accessed November 17, 2019.
- Entry on neon. In: Römpp Online . Georg Thieme Verlag, accessed on June 19, 2014.
- Errol G. Lewars: Modeling Marvels: Computational Anticipation of Novel Molecules. Springer Verlag, 2008, ISBN 978-1-4020-6972-7 , pp. 69-80.
- David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Properties of the Elements and Inorganic Compounds, pp. 4-23.
- G. Audi, FG Kondev, Meng Wang, WJ Huang, S. Naimi: The NUBASE2016 evaluation of nuclear properties. In: Chinese Physics C. Volume 41, 2017, p. 030001, doi: 10.1088 / 1674-1137 / 41/3/030001 ( full text ).
- Neon 4.5. (PDF; 304 kB) Linde AG , May 2, 2011, accessed on June 16, 2018 .
- Walter J. Moore, Dieter O. Hummel: Physikalische Chemie. 4th edition. de Gruyter, 1986, ISBN 3-11-010979-4 , p. 284 ( limited preview in the Google book search).
- Entry on helium-neon laser. In: Römpp Online . Georg Thieme Verlag, accessed on June 19, 2014.
- Alfred A. Bove, Jefferson Carroll Davis: Bove and Davis' diving medicine. 4th edition. Elsevier, 2004, ISBN 0-7216-9424-1 , p. 121.
- Patent US3815591 : Diving gas mixtures and methods of deep diving. Published April 28, 1972 , Applicant: Union Carbide Co., Inventor: Heinz Schreiner, Robert Hamilton, Arthur Francis.