Neon was the second of these three rare gases to be discovered and was immediately recognized as a new element from its bright red emission spectrum. It was discovered (along with krypton and xenon) in 1898 as one of the three residual rare inert elements remaining in dry air, after nitrogen, oxygen, argon and carbon dioxide were removed. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. These ions include Ne+, (NeAr)+, (NeH)+, and (HeNe+).Neon is a chemical element with the symbol Ne and atomic number 10. In addition, research involving specialized techniques (including mass spectrometry) has shown that neon can form various ions, either by itself or in combination with other elements. It does, however, appear to form an unstable hydrate. Given the extreme inertness of neon, its compounds are hard to find. Processing 88,000 pounds of liquid air will produce one pound of neon. 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. Neon remains, along with hydrogen and helium, in the small fraction of air that resists liquefaction upon cooling to −195.8 ☌ (−320.4 ☏, the boiling point of liquid nitrogen). Neon is the 5th most abundant element in the universe however, it is rare on Earth, making up only 0.0018% of Earth's atmosphere. Neon is non-toxic and has no known biological role. Ramsay named the new gas neon, basing it on neos, the Greek word for new. This time they were successful, and when they put a sample of the new gas into their atomic spectrometer, it startled them by the brilliant red glow that we now associate with neon signs. They then repeated their experiment, this time allowing solid argon to evaporate slowly under reduced pressure and collected the gas that came off first.

They had been expecting to find a lighter gas which would fit a niche above argon in the periodic table of the elements. In 1898, William Ramsay and Morris Travers at University College London isolated krypton gas by evaporating liquid argon. Other clinical applications of neon, such as a radiotherapy in various cancers, have been studied. Neon may be used in the clinical setting as a diagnostic tracer gas in a gas analyzer for a lung diffusion test.It has over 40 times more refrigerating capacity per unit volume than liquid helium, and more than 3 times that of liquid hydrogen. Liquid neon is an important cryogenic refrigerant.Neon is also used to make high-voltage indicators and switching gear, lightning arresters, diving equipment and lasers.Others contain different gases to give different colours. Only the red signs actually contain pure neon. In a vacuum discharge tube neon glows a reddish orange colour. The largest use of neon is in making the ubiquitous ‘neon signs’ for advertising.Neon glows reddish-orange in a vacuum discharge tube. Of all the rare gases, neon has the most intense discharge at normal voltages and currents.

Exposure of a container of neon to prolonged heat or fire may cause it to rupture violently and rocket. Because of its low density, neon slowly escapes Earth's atmosphere, making it rare on Earth. The gas is composed of single atoms and is therefore described as 'monatomic.' Neon is 2/3 as dense as air and is the second-lightest noble gas, after helium. Neon appears as a colorless, odorless, noncombustible, and nonreactive gas.

Neon number on periodic table