Neon

s forming neon's element symbol Neon was discovered in 1898 by the British chemists Sir William Ramsay (1852–1916) and Morris Travers (1872–1961) in London. suggested by Ramsay's son. The characteristic brilliant red-orange color emitted by gaseous neon when excited electrically was noted immediately. Travers later wrote: "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget." A second gas was also reported along with neon, having approximately the same density as argon but with a different spectrum – Ramsay and Travers named it metargon. The intense color and vibrancy of neon equated with American society at the time, suggesting a "century of progress" and transforming cities into sensational new environments filled with radiating advertisements and "electro-graphic architecture". Neon played a role in the basic understanding of the nature of atoms in 1913, when J. J. Thomson, as part of his exploration into the composition of canal rays, channeled streams of neon ions through a magnetic and an electric field and measured the deflection of the streams with a photographic plate. Thomson observed two separate patches of light on the photographic plate (see image), which suggested two different parabolas of deflection. Thomson eventually concluded that some of the atoms in the neon gas were of higher mass than the rest. Though not understood at the time by Thomson, this was the first discovery of isotopes of stable atoms. Thomson's device was a crude version of the instrument we now term a mass spectrometer. ==Isotopes==

's photographic plate are the separate impact marks for the two isotopes neon-20 and neon-22. Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). 21Ne and 22Ne are partly primordial and partly nucleogenic (i.e. made by nuclear reactions of other nuclides with neutrons or other particles in the environment) and their variations in natural abundance are well understood. In contrast, 20Ne (the chief primordial isotope made in stellar nucleosynthesis) is not known to be nucleogenic or radiogenic, except from the decay of oxygen-20, which is produced in very rare cases of cluster decay by thorium-228. The causes of the variation of 20Ne in the Earth have thus been hotly debated. In addition, isotopic analysis of exposed terrestrial rocks has demonstrated the cosmogenic (cosmic ray) production of 21Ne. This isotope is generated by spallation reactions on magnesium, sodium, silicon, and aluminium. 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 surface rocks and meteorites. Neon in solar wind contains a higher proportion of 20Ne than nucleogenic and cosmogenic sources. ==Characteristics==

Neon is the second-lightest noble gas, after helium. Like other noble gases, neon is colorless and odorless. It glows reddish-orange in a vacuum discharge tube. It has over 40 times the refrigerating capacity (per unit volume) of liquid helium and three times that of liquid hydrogen. Despite helium surpassing neon in terms of ionization energy, neon is theorized to be the chemically least reactive of all the elements, even less so than the former. Multiple computational studies suggest that helium can form stable chemical species under extreme conditions. The helium hydride ion HeH⁺ has been experimentally observed, and high-pressure solids such as Na2He have also been confirmed. Additionally, theoretical works predict that helium hydride fluoride (HHeF), a neutral compound from HeH+ could be stable under extreme pressure, whereas the analogous neon compound HNeF appears unbound and therefore nonexistent. In contrast, no stable neutral or covalent neon compounds are known to exist under any pressure or temperature. While a neon-containing anion complex [B12(CN)11Ne]- has been predicted theoretically, its existence has yet to be proven experimentally, leaving neon as the only noble gas for which no compounds have been definitively confirmed to exist. of neon shows individual wavelengths of light contributing to its perceived color when heated. Neon plasma has the most intense light discharge at normal voltages and currents of all the noble gases. The average color of this light to the human eye is red-orange due to many lines in this range; it also contains a strong green line, which is hidden, unless the visual components are dispersed by a spectroscope. ==Occurrence==

Stable isotopes of neon are produced in stars. Neon's most abundant isotope 20Ne (90.48%) is created by the nuclear fusion of carbon and carbon in the carbon-burning process of stellar nucleosynthesis. This requires temperatures above 500 megakelvins, which occur in the cores of stars of more than 8 solar masses. Neon is abundant on a universal scale; it is the fifth most abundant chemical element in the universe by mass, after hydrogen, helium, oxygen, and carbon (see chemical element). Its relative rarity on Earth, like that of helium, is due to its relative lightness, high vapor pressure at very low temperatures, and chemical inertness, all properties which tend to keep it from being trapped in the condensing gas and dust clouds that formed the smaller and warmer solid planets like Earth. Neon is monatomic, making it lighter than the molecules of diatomic nitrogen and oxygen which form the bulk of Earth's atmosphere; a balloon filled with neon will rise in air, albeit more slowly than a helium balloon. Neon's abundance in the universe is about 1 part in 750 by mass; in the Sun and presumably in its proto-solar system nebula, about 1 part in 600. The Galileo spacecraft atmospheric entry probe found that in the upper atmosphere of Jupiter, the abundance of neon is reduced (depleted) by about a factor of 10, to a level of 1 part in 6,000 by mass. This may indicate that the ice-planetesimals that brought neon into Jupiter from the outer solar system formed in a region that was too warm to retain the neon atmospheric component (abundances of heavier inert gases on Jupiter are several times that found in the Sun), or that neon is selectively sequestered in the planet's interior. Neon comprises 1 part in 55,000 in the Earth's atmosphere, or 18.2 ppm by volume (this is about the same as the molecule or mole fraction), or 1 part in 79,000 of air by mass. It comprises a smaller fraction in the crust. It is industrially produced by cryogenic fractional distillation of liquefied air. ==Chemistry==

The ions [NeAr]+, [NeH]+, and [HeNe]+ have been observed from optical and mass spectrometric studies. Ne atoms are not bonded to water and can freely move through this material. They can be extracted by placing the clathrate into a vacuum chamber for several days, yielding ice XVI, the least dense crystalline form of water. The familiar Pauling electronegativity scale relies upon chemical bond energies, but such values have obviously not been measured for inert helium and neon. The Allen electronegativity scale, which relies only upon (measurable) atomic energies, identifies neon as the most electronegative element, closely followed by fluorine and helium. The triple point temperature of neon (24.5561 K) is a defining fixed point in the International Temperature Scale of 1990. ==Production==

Neon is produced from air in cryogenic air-separation plants. A gas-phase mixture mainly of nitrogen, neon, helium, and hydrogen is withdrawn from the main condenser at the top of the high-pressure air-separation column and fed to the bottom of a side column for rectification of the neon. It can then be further purified from helium by bringing it into contact with activated charcoal. Hydrogen is purified from the neon by adding oxygen so water is formed and is condensed. as a by-product of steel production in Russia. , the company Iceblick, with plants in Odesa and Moscow, supplies 65% of the world's production of neon, as well as 15% of the krypton and xenon. and toward suppliers in China. The closure was predicted to exacerbate the COVID-19 chip shortage, which may further shift neon production to China. ==Applications==

Lighting and signage , florist shop|300x300pxTwo quite different kinds of neon lighting are in common use. Neon glow lamps are generally tiny, with most operating between 100 and 250 volts. They have been widely used as power-on indicators and in circuit-testing equipment, but light-emitting diodes (LEDs) now dominate in those applications. These simple neon devices were the forerunners of plasma displays and plasma television screens. Neon signs typically operate at much higher voltages (2–15 kilovolts), and the luminous tubes are commonly meters long. The glass tubing is often formed into shapes and letters for signage, as well as architectural and artistic applications. In neon signs, neon produces an unmistakable bright reddish-orange light when electric current passes through it under low pressure. Although tube lights with other colors are often called "neon", they use different noble gases or varied colors of fluorescent lighting, for example, argon produces a lavender or blue hue. As of 2012, there are over one hundred colors available. Other Neon is used in vacuum tubes, high-voltage indicators, lightning arresters, wavemeter tubes, television tubes, and helium–neon lasers. Gas mixtures that include high-purity neon are used in lasers for photolithography in semiconductor device fabrication. Liquefied neon is commercially used as a cryogenic refrigerant in applications not requiring the lower temperature range attainable with the more extreme liquid helium refrigeration. ==References==