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Jai Ganesh

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Registered: 2005-06-28

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Neon

Neon

Gist

Neon is used in vacuum tubes, high-voltage indicators, lightning arresters, wavemeter tubes, television tubes, and helium–neon lasers.

Summary

Neon (Ne), chemical element, inert gas of Group 18 (noble gases) of the periodic table, used in electric signs and fluorescent lamps. Colourless, odourless, tasteless, and lighter than air, neon gas occurs in minute quantities in Earth’s atmosphere and trapped within the rocks of Earth’s crust. Though neon is about 3 1/2 times as plentiful as helium in the atmosphere, dry air contains only 0.0018 percent neon by volume. This element is more abundant in the cosmos than on Earth. Neon liquefies at −246.048 °C (−411 °F) and freezes at a temperature only 2 1/2° lower. When under low pressure, it emits a bright orange-red light if an electrical current is passed through it. This property is utilized in neon signs (which first became familiar in the 1920s), in some fluorescent and gaseous conduction lamps, and in high-voltage testers. The name neon is derived from the Greek word neos, “new.”

Neon was discovered (1898) by the British chemists Sir William Ramsay and Morris W. Travers as a component of the most volatile fraction of liquefied crude argon obtained from air. It was immediately recognized as a new element by its unique glow when electrically stimulated. Its only commercial source is the atmosphere, in which it is 18 parts per million by volume. Because its boiling point is −246 °C (−411 °F), neon remains, along with helium and hydrogen, in the small fraction of air that resists liquefaction upon cooling to −195.8 °C (−320.4 °F, the boiling point of liquid nitrogen). Neon is isolated from this cold, gaseous mixture by bringing it into contact with activated charcoal, which adsorbs the neon and hydrogen; removal of hydrogen is effected by adding enough oxygen to convert it all to water, which, along with any surplus oxygen, condenses upon cooling. Processing 88,000 pounds of liquid air will produce one pound of neon.

No stable chemical compounds of neon have been observed. Molecules of the element consist of single atoms. Natural neon is a mixture of three stable isotopes: neon-20 (90.92 percent); neon-21 (0.26 percent); and neon-22 (8.82 percent). Neon was the first element shown to consist of more than one stable isotope. In 1913, application of the technique of mass spectrometry revealed the existence of neon-20 and neon-22. The third stable isotope, neon-21 was detected later. Twelve radioactive isotopes of neon also have been identified.

Element Properties

atomic number  :  10
atomic weight  :  20.183
melting point  :  −248.67 °C (−415.5 °F)
boiling point  :  −246.048 °C (−411 °F)
density (1 atm, 0° C)  :  0.89990 g/litre
oxidation state  :  0

Details

Neon is a chemical element; it has symbol Ne and atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of air.

Neon was discovered in 1898 alongside krypton and xenon, identified as one of the three remaining rare inert elements in dry air after the removal of nitrogen, oxygen, argon, and carbon dioxide. Its discovery was marked by the distinctive bright red emission spectrum it exhibited, leading to its immediate recognition as a new element. The name neon originates from the Greek word νέον, a neuter singular form of νέος (neos), meaning 'new'. Neon is a chemically inert gas; although neon compounds do exist, they are primarily ionic molecules or fragile molecules held together by van der Waals forces.

The synthesis of most neon in the cosmos resulted from the nuclear fusion within stars of oxygen and helium through the alpha-capture process. Despite its abundant presence in the universe and Solar System—ranking fifth in cosmic abundance following hydrogen, helium, oxygen, and carbon—neon is comparatively scarce on Earth. It constitutes about 18.2 ppm of Earth's atmospheric volume and a lesser fraction in the Earth's crust. The high volatility of neon and its inability to form compounds that would anchor it to solids explain its limited presence on Earth and the inner terrestrial planets. Neon’s high volatility facilitated its escape from planetesimals under the early Solar System's nascent Sun's warmth.

Neon's notable applications include its use in low-voltage neon glow lamps, high-voltage discharge tubes, and neon advertising signs, where it emits a distinct reddish-orange glow. This same red emission line is responsible for the characteristic red light of helium–neon lasers. Although neon has some applications in plasma tubes and as a refrigerant, its commercial uses are relatively limited. It is primarily obtained through the fractional distillation of liquid air, making it significantly more expensive than helium due to air being its sole source.

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