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Neon

2007 Schools Wikipedia Selection. Related subjects: Chemical elements


                10                fluorine ← neon → sodium
                He
                ↑
                Ne
                ↓
                Ar

                                  Periodic Table - Extended Periodic Table

                                                                   General
                                         Name, Symbol, Number neon, Ne, 10
                                               Chemical series noble gases
                                             Group, Period, Block 18, 2, p
                                                      Appearance colorless
                                             Atomic mass 20.1797 (6) g/mol
                                     Electron configuration 1s^2 2s^2 2p^6
                                                  Electrons per shell 2, 8
                                                       Physical properties
                                                                 Phase gas
                                              Density (0 °C, 101.325 kPa)
                                                                0.9002 g/L
                                                    Melting point 24.56  K
                                              (-248.59 ° C, -415.46 ° F)
                                                     Boiling point 27.07 K
                                              (-246.08 ° C, -410.94 ° F)
                                           Critical point 44.4 K, 2.76 MPa
                                         Heat of fusion 0.335 kJ·mol^−1
                                    Heat of vaporization 1.71 kJ·mol^−1
                         Heat capacity (25 °C) 20.786 J·mol^−1·K^−1

   CAPTION: Vapor pressure

                                            P/Pa  1  10 100 1 k 10 k 100 k
                                           at T/K 12 13 15  18   21   27

                                                         Atomic properties
                                     Crystal structure cubic face centered
                                                  Oxidation states no data
                                                       Ionization energies
                                          ( more) 1st: 2080.7 kJ·mol^−1
                                                  2nd: 3952.3 kJ·mol^−1
                                                    3rd: 6122 kJ·mol^−1
                                               Atomic radius (calc.) 38 pm
                                                     Covalent radius 69 pm
                                               Van der Waals radius 154 pm
                                                             Miscellaneous
                                             Magnetic ordering nonmagnetic
                      Thermal conductivity (300 K) 49.1 mW·m^−1·K^−1
                                       Speed of sound (gas, 0 °C) 435 m/s
                                             CAS registry number 7440-01-9
                                                         Selected isotopes

                   CAPTION: Main article: Isotopes of neon

                                 iso    NA   half-life DM DE ( MeV)  DP
                                ^20Ne 90.48% Ne is stable with 10 neutrons
                                ^21Ne 0.27%  Ne is stable with 11 neutrons
                                ^22Ne 9.25%  Ne is stable with 12 neutrons

                                                                References

   Neon ( IPA: /ˈniːɒn/) is the chemical element in the periodic table
   that has the symbol Ne and atomic number 10. A colorless, nearly inert
   noble gas, neon gives a distinct reddish glow when used in vacuum
   discharge tubes and neon lamps and is found in air in trace amounts.

Notable characteristics

   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). In most applications it is a less expensive refrigerant
   than helium. Neon has the most intense discharge at normal voltages and
   currents of all the rare gases.

Applications

   Neon is often used in signs and produces an unmistakable bright orange
   colored light. All other colors (though still referred to as "neon")
   are created using a mercury vapor discharge which excites a phosphor
   via fluorescence.
   Enlarge
   Neon is often used in signs and produces an unmistakable bright orange
   colored light. All other colors (though still referred to as "neon")
   are created using a mercury vapor discharge which excites a phosphor
   via fluorescence.

   The reddish-orange colour 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:
     * vacuum tubes
     * high-voltage indicators
     * lightning arrestors
     * wave meter tubes
     * television tubes
     * Neon and helium are used to make a type of gas laser
     * Liquefied neon is commercially used as a cryogenic refrigerant in
       applications not requiring the lower temperature range attainable
       with more expensive liquid helium refrigeration.

History

   Neon ( Greek νέος meaning "new") was discovered by Scottish chemist
   William Ramsay and English chemist Morris Travers in 1898.

Occurrence

   Neon is a monatomic gas at standard conditions. Neon is rare, found in
   the Earth's atmosphere at 1 part in 65,000 and industrially produced by
   cryogenic fractional distillation of liquified air.

Compounds

   The ions, Ne^+, (NeAr)^+, (NeH)^+, and (HeNe^+), have been observed
   from optical and mass spectrometric research. In addition, neon forms
   an unstable hydrate.

Isotopes

   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 been hotly debated. The
   principal nuclear reactions which generate neon isotopes 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 aluminium. 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.
   Retrieved from " http://en.wikipedia.org/wiki/Neon"
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   with only minor checks and changes (see www.wikipedia.org for details
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