|
Name: Neon |
Boiling Point: 27.246°K, -245.904°C, -410.6°F Melting Point: 24.703°K, -248.447°C, -415.205°F Electrons Energy Level: 2, 8 Isotopes: 13 + 3 Stable Heat of Vaporization: 1.7326 kJ/mol Heat of Fusion: 0.3317 kJ/mol Density: 0.9 g/L @ 273K & 1atm Specific Heat: 0.904 J/g°K Atomic Radius: 0.51Å Ionic Radius: unknown Electronegativity: N/A (Pauling); 4.84 (Allrod Rochow) |
| Neon (Greek
meaning "new") was discovered in 1898 Scottish chemist William Ramsay and
English chemist Morris Travers in London, England. Neon is perhaps the best known noble gas because of its use in so-called "neon" lights (many of which actually contain other gases) and is relatively plentiful in the earth's atmosphere. Neon is actually abundant on a universal scale: the fifth most abundant chemical element in the universe by mass, after hydrogen, helium, oxygen, and carbon. Its relative rarity on Earth, like that of helium, is due to its relative lightness and chemical inertness, both properties keeping it from being trapped in the condensing gas and dust clouds of the formation of smaller and warmer solid planets like Earth. Mass abundance in the universe is about 1 part in 750 and in the Sun and presumably in the proto-solar system nebula, about 1 part in 600. The Galileo spacecraft atmospheric entry probe found that even in the upper atmosphere of Jupiter, neon is reduced by about a factor of 10, to 1 part in 6,000 by mass. This may indicate that even the ice-planetesmals which brought neon into Jupiter from the outer solar system, formed in a region which was too warm for them to have kept their neon (abundances of heavier inert gases on Jupiter are several times that found in the Sun). No stable compounds of neon are known to date. The gas is extracted from air by liquefaction. Neon is the second-lightest noble gas, glows reddish-orange in a vacuum discharge tube and has over 40 times the refrigerating capacity of liquid helium and three times that of liquid hydrogen (on a per unit volume basis); it also contains a strong green line which is hidden, unless the visual components are dispersed by a spectroscope. In most applications it is a less expensive refrigerant than helium. Neon plasma has the most intense light discharge at normal voltages and currents of all the rare gases. |
2 He 4.002 |
| 10 Ne 20.17 |
|
| 18 Ar 39.94 |
|
| 36 Kr 83.80 |
|
| 54 Xe 131.3 |
|
| 86 Rn 222.0 |
|
| 118 Uuo 293.0 |
1s2 2s2p6
The reddish-orange color that neon emits in neon lights is widely used to make advertising signs and is also used in long tubular strips in car modification. The word "neon" is also used generically for these types of lights even though many other gases are used to produce different colors of light. Other uses:
Neon is a monatomic gas at standard conditions. Neon is rare on Earth, found in the Earth's atmosphere at 1 part in 65,000 (by volume) or 1 part in 83,000 by mass. It is industrially produced by cryogenic fractional distillation of liquefied air.
| 1s2 | ||
| 2s2 | 2p6 |
The ions, Ne+, (NeAr)+, (NeH)+, and (HeNe+), have been observed from optical and mass spectrometric research. In addition, neon forms an unstable hydrate.
Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). 21Ne and 22Ne are nucleogenic and their variations are well understood. In contrast, 20Ne is not known to be nucleogenic and the causes of its variation in the Earth have have been hotly debated. The principal nuclear reactions which generate neon isotope are neutron emission, alpha decay reactions on 24Mg and 25Mg, which produce 21Ne and 22Ne, respectively. The alpha particles are derived from uranium-series decay chains, while the neutrons are mostly produced by secondary reactions from alpha particles. The net result yields a trend towards lower 20Ne/22Ne and higher 21Ne/22Ne ratios observed in uranium-rich rocks such as granites. Isotopic analysis of exposed terrestrial rocks has demonstrated the cosmogenic production of 21Ne. This isotope is generated by spallation reactions on magnesium, sodium, silicon, and aluminum. 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 surficial rocks and meteorites.
Similar to xenon, neon content observed in samples of volcanic gases are enriched in 20Ne, as well as nucleogenic 21Ne, relative to 22Ne content. The neon isotopic content of these mantle-derived samples represent a non-atmospheric source of neon. The 20Ne-enriched components are attributed to exotic primordial rare gas components in the Earth, possibly representing solar neon. Elevated 20Ne abundances are also found in diamonds, further suggesting a solar neon reservoir in the Earth.
| Isotope | Atomic Mass | Half-Life |
|---|---|---|
| Ne16 | 16.0258 | 122 keV |
| Ne17 | 17.0177 | 109.2ms |
| Ne18 | 18.0057 | 1672 ms |
| Ne19 | 19.0019 | 17.22 seconds |
| Ne20 | 19.9924 | Stable |
| Ne21 | 20.9938 | Stable |
| Ne22 | 21.9914 | Stable |
| Ne23 | 22.9945 | 37.24 seconds |
| Ne24 | 23.9936 | 3.38 minutes |
| Ne25 | 24.9978 | 602 ms |
| Ne26 | 26.0005 | 197 ms |
| Ne27 | 27.0076 | 32 ms |
| Ne28 | 28.012 | 17 ms |
| Ne29 | 29.019 | 0.2 seconds |
| Ne30 | 30.024 | >200 ns |
| Ne31 | 31.033 | |
| Ne32 | 32.04 | >200 ns |
Neon was discovered by Sir William Ramsay, a Scottish chemist, and Morris M. Travers, an English chemist, shortly after their discovery of the element krypton in 1898. Like krypton, neon was discovered through the study of liquefied air. Although neon is the fourth most abundant element in the universe, only 0.0018% of the earth's atmosphere is neon.
The largest use for neon gas is in advertising signs. Neon is also used to make high voltage indicators and is combined with helium to make helium-neon lasers. Liquid neon is used as a cryogenic refrigerant. Neon is highly inert and forms no known compounds, although there is some evidence that it could form a compound with fluorine.
| Neon Data |
Atomic Structure Atomic Radius (Å): 0.51Å Electrochemical Equivalents: unknown Atomic Mass Average: 20.1797 |
(Gr. neos, new) Discovered by Ramsay and Travers in 1898. Neon is a rare gaseous element present in the atmosphere to the extent of 1 part in 65,000 of air. It is obtained by liquefaction of air and separated from the other gases by fractional distillation. Natural neon is a mixture of three isotopes. Six other unstable isotopes are known. It is a very inert element; however, it is said to form a compound with fluorine. It is still questionable if true compounds of neon exist, but evidence is mounting in favor of their existence. The following ions are known from optical and mass spectrometric studies: Ne+, (NeAr)+, (NeH)+, and (HeNe+). Neon also forms an unstable hydrate. In a vacuum discharge tube, neon glows reddish orange. Of all the rare gases, the discharge of neon is the most intense at ordinary voltages and currents. Neon is used in making the common neon advertising signs, which account for its largest use. It is also used to make high-voltage indicators, lightning arrestors, wave meter tubes, and TV tubes. Neon and helium are used in making gas lasers. Liquid neon is now commercially available and is finding important application as an economical cryrogenic refrigerant. It has over 40 times more refrigerating capacity per unit volume than liquid helium and more than three times that of liquid hydrogen. It is compact, inert, and is less expensive than helium when it meets refrigeration requirements. Neon costs about $2.00/l.
Source: CRC Handbook of Chemistry and Physics, 1913-1995. David R. Lide, Editor in Chief. Author: C.R. Hammond