Inert gas

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The noble gases are made up of the elements in Group 18 (Group VIII), shown here in light blue. Click to enlarge.

Inert gases, also known as noble gases, are gases that will not combine with any known element. At present, six are known: argon, helium, xenon, radon, neon and krypton. Only argon and helium are used as shielding gases for welding.^[1] These gases are only used for nonferrous welding due to lack of adequate penetration of the weld when using pure argon and an erratic arc and increased spatter when using pure helium. Blends of inert and/or semi-inert gases are often used to take advantage of the positive features of each gas while minimizing the negative.^[2]

Inert gases are any of the elements in Group O (Group 18) of the periodic table, which are monatomic and with limited exceptions chemically inert.^[3]

Source(s): Inert gas

Sources of Inert Gases

Air is the major commercial source of argon, xenon, krypton and neon, which are commonly obtained by fractional distillation and liquefaction. Helium is commonly isolated from natural gas wells, while radon is commonly produced from the radioactive decomposition of radium compounds. Despite being the second-most abundant element in the universe, helium has been the subject of an ongoing world-wide shortage since 2006.

Source(s): Inert gas

The Seventh Noble Gas

A seventh noble gas, element 118 (known temporarily as ununoctium, with the symbol Uuo), was synthesized by scientists in 2002 and 2005 using a particle accelerator. Only three atoms of the element have been produced, leaving scientists unable to determine the physical or chemical properties of the atom.^[4]

Nitrogen is also highly inert, and is sometimes mistaken for an inert gas. However, it forms several compounds, including nitrous oxide, ammonia and nitrogen dioxide, and is therefore not an inert gas.^[5]

Source(s): Inert gas

Uses of Inert Gases

Due to their inertness, or inability to react chemically with other elements, noble gases are commonly used in wine making and wine preservation. The inert gas displaces oxygen in the bottle headspace, preventing oxidation and spoilage by yeast and bacteria and keeping the wine fresh for longer. Other gases, including nitrogen and carbon dioxide, are commonly used in place of inert gas.^[6]

Inert gases are also used in the trimix and nitrox breathing mixtures used by SCUBA divers. Helium and argon are the most commonly used.^[7]

Source(s): Inert gas

References

1. http://www.millerwelds.com/interests/instructors/pdf/Glossary.pdf
2. http://www.answers.com/topic/noble-gas
3. http://www.environics.com/welding-applications/
4. http://www.britannica.com/EBchecked/topic/416955/noble-gas
5. http://www.wineqc.com/papers/inertgas/inertgas.html
6. http://www.uigi.com/nitrogen.html
7. http://www.environics.com/