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# Chemistry of Neon (Z=10)

Neon is a member of the group 18 elements, the noble gases. This element is most commonly known through its use in glow lamps and advertising signs emitting a distinctive bright orange-red color.

### General Properties

• Symbol: Ne
• Atomic Number: 10
• Atomic weight 20.1797 g/mol
• Electron Configuration: [He] 2s22p6
• Colorless and odorless gas
• Melting point: 24.56 K
• Boiling point: 27.07 K
• Density: 0.0008999 g/cm3
• 3 Stable isotopes
• Crystal Structure: Face Centered
• Fourth most abundant element in universe
• Rare on earth: 0.001818% atmosphere
•  Ionization Energy: 21.565 eV

Figure 1: Electron Diagram of Neon. Image courtesy of xxx

### History and Origin

The name for the element Neon is derived from the Greek word for new, “neos”.  Since neon and the other noble gases are highly unreactive and only found in trace amounts in the atmosphere, they were not discovered until the late nineteenth century. Neon was discovered in 1898 by English chemists Sir William Ramsay and Morris M. Travers, along with Krypton and Xenon. They accomplished the isolation of these inert gases by fractional distillation of air. Through a two step process of condensation then evaporation, they were able to trap other components of the air. Initially, the group 18 elements were considered to be inert gases, as they were highly unreactive with any other element. However, in 1962 compounds of Xenon and Krypton compounds were synthesized with Fluorine, disproving their inert quality. Therefore, these elements were renamed the noble gases.

### Occurrence

Neon is the fourth most abundant element in the entire universe, behind hydrogen, helium and oxygen. However, it is considered very rare on Earth as it can mainly be found in the atmosphere, which consists only 0.001818% of Neon in volume. This is because it is highly inert, very light, and has high vapor pressure at low temperatures. These properties explain why smaller, warmer, and solid planets like Earth are less abundant in Neon. Although, small traces of Neon can be encountered in the Earth's crust and ocean. Its estimated abundance is 5×10-3 mg/Kg and 1.2×10-4 mg/L respectively. Neon is the second lightest noble gas and is a monatomic gas, therefore found as Ne and not Ne2.

### Formation of Compounds and Isotopes

A neon compound is still yet to be theoretically identified although the gas phase ions like $$NeAr^+$$, $$NeH^+$$, $$HeNe^+$$ have been resolved from mass spectrometry studies.

The average atomic mass of neon is 20.1797 u. Neon is known to have over nineteen different isotopes ranging from 16-34 in isotopic mass. However, neon only has three stable isotopes: 20Ne, 21Ne, and 22Ne. The most abundant of those stable isotopes (no t1/2 or decay) is 20Ne at about 90% via alpha decay of Mg-25 to form Ne-21.

$\ce{^{25}_{12}Mg \rightarrow ^{21}_{10}Ne + ^{4}_{2}He}$

### Applications and Uses

Neon is most notable for its use in neon lighting and signs. These neon lights are made with filled glass or plastic tubes with Neon gas.  As electricity passes through these tubes, electric discharge produces high-energy electrons that hit the neon atoms changing their energy state, as photon of light is emitted. These glass tubings can be shaped and twisted to form various designs.

It is a common misconception that all “neon” lights are made entirely of neon, as they do not change colors. Tubes filled solely with the Ne (g) emit the bright orange-red color. The different colors of lights are made by mixing other noble gases and elements. Over 150 colors can be made. (Ex: Mercury emits a light blue color). Other commercial uses for Neon are in high-voltage indicators, TV tubes, lightning arresters, and helium-gas lasers. Also, liquid neon is used as an economical cryogenic refrigerant.

*(Lightning Arrestor in a telephone pole to limit power surges)

### Problems

1. What is the electron configuration of Ne+?
2. Describe the process of fractional distillation of air.
3. Why is Neon not abundant on Earth?
4. Can the inert gas Neon react to form a compound?
5. What color is a “neon light” that is filled with Argon and phosphor?

### Solutions

1. [He] 2s2 2p5
2. Fractional distillation refers to the process of breaking down a mixture into its component parts. For air, it is accomplished by cooling the air until it is a liquid and then boiling and waiting for evaporation. The different gases are then separated.
3. Neon is inert, light, and has high vapor pressure at low temperatures. Therefore, it is rarer on smaller and warmer planets such as Earth.
4. Yes, neon is found to react with fluoride to form Neon Fluoride because F is highly electronegative and is forced to react under high temperatures.
5. The light emitted is a bold yellow color.

### References

1. Petrucci, Ralph, et.al. General Chemistry: Principles and Modern Applications. 9th ed. New Jersey: Prentice Hall, 2007. Print.
2. Hyman, Herbert H. "Noble Gas Compounds" Science. 5 July, 1963: 61-63
3. Fung, Bing-Man. "The Electronegativity of Noble Gases." J. Phys. Chem., 196569 (2), pp 596–600
4. "The Isotopes of Neon. " J. Chem. Educ., 1929, 6 (4), p 707

### Contributors

• Jonathan Molina - (UCD)