Noble gas

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Group	18
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The noble gases are the chemical elements in group 18 (old-style Group 0) of the periodic table. This chemical series contains helium, neon, argon, krypton, xenon, and radon.

1 Etymology
2 Chemistry
3 Applications
4 Physical Properties
5 External links

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Etymology

The noble gases were previously referred to as inert gases, but this term is not strictly accurate because several of them do take part in chemical reactions. Another older term was rare gases, although in fact argon forms a considerable part (0.93% by volume, 1.29% by mass) of the Earth's atmosphere.

The name 'noble gases' is an allusion to the similarly unreactive Noble metals, so called due to their preciousness, resistance to corrosion and long association with the aristocracy.

**Explanation of above periodic table slice:**
Noble gases	atomic number in Template:Element color/Gas are gases	solid borders are primordial elements (older than the Earth)	dashed borders are naturally radioactive elements	dotted borders are radioactive, synthetic elements	those without borders have not been discovered yet

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Chemistry

The general physical properties of Noble gases are:

They are all monatomic molecules and chemically inert (unreactive), except for Kr and Xe, which have shown some reactivity in the laboratory—see noble gas compounds.

The noble gases' lack of reactivity is due to their having a complete valence shell. They have little tendency to gain or lose electrons. The noble gases have high ionization energies and negligible electronegativities. The noble gases have low boiling points and are all gases at room temperature.

Because of their unreactivity, the noble gases were not discovered until 1868, when helium was detected spectrographically in the Sun. The isolation of helium on Earth had to wait until 1895. The noble gases have very weak inter-atomic forces of attraction, and consequently very low melting points and boiling points. This is why they are all gases under normal conditions, even those with larger atomic masses than many normally solid elements.

Ununoctium

No isotopes with 118 protons have yet been detected in nature or synthesized in the laboratory. In the meantime, the systematic name "ununoctium" is used to refer to this hypothetical element. If discovered, ununoctium is expected to be another noble gas, filling the empty space in the periodic table beneath radon. All its isotopes are likely to be radioactive with a very short half-life in the millisecond range.

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Applications

One of the most commonly encountered uses of the noble gases in everyday life is in lighting. Argon is often used as a suitable safe and inert atmosphere for the inside of filament light bulbs. Some of the noble gases glow distinctive colours when used inside lighting tubes (neon lights). Helium, due to its unreactivity (compared to flammable hydrogen) and lightness, is often used in blimps and balloons.

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Physical Properties

Template:Start box | align = center | Property

|- | align = center | Element Number | align = center | 2 | align = center | 10 | align = center | 18 | align = center | 36 | align = center | 54 | align = center | 86 | align = center | 118 |- | align = center | Element Name | align = center | Helium | align = center | Neon | align = center | Argon | align = center | Krypton | align = center | Xenon | align = center | Radon | align = center | Ununoctium |- | align = center | Normal Density | align = center | 0.1786 | align = center | 0.9002 | align = center | 1.7818 | align = center | 3.708 | align = center | 5.851 | align = center | 9.97 | align = center | N/A |- | align = center | Atomic Mass | align = center | 4.00 | align = center | 20.2 | align = center | 39.9 | align = center | 82.92 | align = center | 130.2 | align = center | 222.4 | align = center | N/A |- | align = center | Boiling Pt. (°C) | align = center | -268.83 | align = center | -245.92 | align = center | -185.81 | align = center | -151.7 | align = center | -106.6 | align = center | -62 | align = center | N/A |- | align = center | Melting Pt. (°C) | align = center | -272 | align = center | -248.52 | align = center | -189.6 | align = center | -157 | align = center | -111.5 | align = center | -71 | align = center | N/A

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External links

Ohio State University press release for uranium compounds with noble gases.
Rare Gases - Neon, Krypton, Xenon Properties, Uses, Applications
Argon Ar Properties, Uses, Applications
Science Aid: Noble gases Simple look at the properties and uses of noble gases

Periodic tables
Standard table \| Vertical table \| Table with names \| Names and atomic masses (large) \| Names and atomic masses (small) \| Names and atomic masses (text only) \| Inline F-block \| Elements to 218 \| Electron configurations \| Metals and nonmetals \| Table by blocks
Lists of elements
Name \| Atomic symbol \| Atomic number \| Boiling point \| Melting point \| Density \| Atomic mass
Groups: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18
Periods: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9
Series: Alkalis - Alkaline earths - Lanthanides - Actinides - Transition metals - Poor metals - Metalloids - Nonmetals - Halogens - Noble gases
Blocks: s-block - p-block - d-block - f-block - g-block