Neon From Wikipedia, the free encyclopedia This article is about the noble gas. For other uses, see Neon (disambiguation). Neon 10Ne ↑ Ne ↓ Ar fluorine ← neon → sodium Neon in the periodic table Appearance colorless gas exhibiting an orange-red glow when placed in a high voltage electric field Spectral lines of neon in the visible region General properties Name, symbol, number neon, Ne, 10 Pronunciation /ˈniːɒn/ Element category noble gases Group, period, block 18 (noble gases), 2, p Standard atomic weight 20.1797(6) Electron configuration [He] 2s2 2p6 2, 8 Physical properties Phase gas Density (0 °C, 101.325 kPa) 0.9002 g/L Liquid density at b.p. 1.207[1] g·cm−3 Melting point 24.56 K, -248.59 °C, -415.46 °F Boiling point 27.104 K, -246.046 °C, -410.883 °F Triple point 24.556 K, 43.37[2][3] kPa Critical point 44.4918 K, 2.7686[3] MPa Heat of fusion 0.335 kJ·mol−1 Heat of vaporization 1.71 kJ·mol−1 Molar heat capacity 5R/2 = 20.786 J·mol−1·K−1 Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 12 13 15 18 21 27 Atomic properties Oxidation states 1[4], 0 Ionization energies (more) 1st: 2080.7 kJ·mol−1 2nd: 3952.3 kJ·mol−1 3rd: 6122 kJ·mol−1 Covalent radius 58 pm Van der Waals radius 154 pm Miscellanea Crystal structure face-centered cubic Neon has a face-centered cubic crystal structure Magnetic ordering diamagnetic[5] Thermal conductivity 49.1×10−3 W·m−1·K−1 Speed of sound (gas, 0 °C) 435 m·s−1 Bulk modulus 654 GPa CAS registry number 7440-01-9 History Prediction William Ramsay (1897) Discovery William Ramsay & Morris Travers[6] (1898) First isolation William Ramsay & Morris Travers[7] (1898) Most stable isotopes Main article: Isotopes of neon iso NA half-life DM DE (MeV) DP 20Ne 90.48% 20Ne is stable with 10 neutrons 21Ne 0.27% 21Ne is stable with 11 neutrons 22Ne 9.25% 22Ne is stable with 12 neutrons v t e · references Neon is a chemical element with symbol Ne and atomic number 10. It is in group 18 (noble gases) of the periodic table. 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 as one of the three residual rare inert elements remaining in dry air, after nitrogen, oxygen, argon and carbon dioxide are removed. 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, neuter singular form of νέος [neos], meaning new. Neon is chemically inert and forms no uncharged chemical compounds. During cosmic nucleogenesis of the elements, large amounts of neon are built up from the alpha-capture fusion process in stars. Although neon is a very common element in the universe and solar system (it is fifth in cosmic abundance after hydrogen, helium, oxygen and carbon), it is very rare on Earth. It composes about 18.2 ppm of air by volume (this is about the same as the molecular or mole fraction), and a smaller fraction in Earth's crust. The reason for neon's relative scarcity on Earth and the inner (terrestrial) planets, is that neon forms no compounds to fix it to solids, and is highly volatile, therefore escaping from the planetesimals under the warmth of the newly ignited Sun in the early Solar System. Even the atmosphere of Jupiter is somewhat depleted of neon, presumably for this reason. Neon gives a distinct reddish-orange glow when used in either low-voltage neon glow lamps or in high-voltage discharge tubes or neon advertising signs.[8][9] The red emission line from neon is also responsible for the well known red light of helium–neon lasers. Neon is used in a few plasma tube and refrigerant applications but has few other commercial uses. It is commercially extracted by the fractional distillation of liquid air. It is considerably more expensive than helium, since air is its only source. Contents [hide] 1 History 2 Isotopes 3 Characteristics 4 Occurrence 5 Applications 6 Compounds 7 See also 8 References 9 External links History[edit] Neon gas-discharge lamps forming the symbol for neon "Ne" Neon (Greek νέον (neon), neuter singular form of νέος meaning "new"), was discovered in 1898 by the British chemists Sir William Ramsay (1852–1916) and Morris W. Travers (1872–1961) in London, England.[10] Neon was discovered when Ramsay chilled a sample of air until it became a liquid, then warmed the liquid and captured the gases as they boiled off. The gases nitrogen, oxygen, and argon had been identified, but the remaining gases were isolated in roughly their order of abundance, in a six-week period beginning at the end of May 1898. First to be identified was krypton. The next, after krypton had been removed, was a gas which gave a brilliant red light under spectroscopic discharge. This gas, identified in June, was named neon, the Greek analogue of "novum", (new), the name Ramsay's son suggested.[11] The characteristic brilliant red-orange color that is 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."[12] Finally, the same team discovered xenon by the same process, in June. Neon's scarcity precluded its prompt application for lighting along the lines of Moore tubes, which used nitrogen and which were commercialized in the early 1900s. After 1902, Georges Claude's company, Air Liquide, was producing industrial quantities of neon as a byproduct of his air liquefaction business. In December 1910 Claude demonstrated modern neon lighting based on a sealed tube of neon. Claude tried briefly to get neon tubes to be used for indoor lighting, due to their intensity, but failed, as homeowners rejected neon light sources due to their color. Finally in 1912, Claude's associate began selling neon discharge tubes as advertising signs, where they were instantly more successful as eye catchers. They were introduced to the U.S. in 1923, when two large neon signs were bought by a Los Angeles Packard car dealership. The glow and arresting red color made neon advertising completely different from the competition.[13] 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 their deflection by placing a photographic plate in their path. 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. It was made by using a crud