Neo (neon) is a chemical element with the symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air. It was discovered (along with krypton and xenon) in 1898 by Scottish chemist Sir William Ramsay and English physicist Lord Rayleigh in London. 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. The name neon is derived from the Greek word νέον (neos), meaning new.
Neon is chemically inert and forms no uncharged chemical compounds except for ionic ones like NaNe. Although many noble gases are known, only argon, helium, krypton, neon, radon and xenon occur naturally in significant quantities on Earth because of their extremely low reactivity under normal conditions; all other known noble gases have been artificially produced.
The complete octet (eight electrons) in the outer atomic shell makes neon very stable against further oxidation or reduction reactions; as a result it has few natural sources other than air: most neon found commercially comes from liquefying air using cryogenic distillation techniques that separate liquid nitrogen ((N2))boiling at 77 K (−196 °C; −321 °F) from gaseous oxygen ((O2)).
When isolated in an unreactive container such as an evacuated glass tube coated inside with silica deposits or paraffin wax we can see evidence of this stability: over time samples of gaseous neon slowly change color from reddish-orange to yellow due to surface deposition of impurities such as sodium ((Na))from contaminating materials used to manufacture the glass containers; This effect can be minimized by using purified quartz glass instead((SiO2)).
In addition to being almost completely inert under ordinary laboratory conditions there are several other properties of neon that make it useful: its low freezing point (−248 °C; −415 °F), lack of coloration when evaporated into vacuum((thus allowing easy detection by means of an incandescent light bulb)), high thermal conductivity(14 times that of dry air), unique among all elements in having more than one stable isotope((20Ne & 22Ne)), electronegativity similar to that of hydrogen((1st row elements on periodic table generally have higher electronegativities while those on 2nd row have lower values relative to 1st row)) making it attracted to metals rather than nonmetals thus giving rise to interesting electrical discharge phenomena including plasma arcs used for welding purposes.(A plasma arc weld torch uses an electrode composed mainly of tungsten which has been socialized with thorium oxide—ThO2—to form what is called a “thorium tungsten” electrode.)