Is one that does not enter into known chemical combination, either with itself or another element. The known inert gases: helium, neon, argon, krypton, xenon, radon.
They have extremely low reactivity with other substances. The noble gases—helium, argon, neon, xenon, krypton, radon, and element 118 (Uuo) – exist in their elemental form and are found in Group 18 of the periodic table.
The inert gases are obtained by fractional distillation of air, with the exception of helium which is separated from a few natural gas sources rich in this element, through cryogenic distillation or membrane separation. For specialized applications, purified inert gas shall be produced by specialized generators on-site. They are often used by chemical tankers and product carriers (smaller vessels). Benchtop specialized generators are also available for laboratories.
Applications:
Because of the non-reactive properties of inert gases, they are often useful to prevent undesirable chemical reactions from taking place. Food is packed in an inert gas to remove oxygen gas. This prevents bacteria from growing. It also prevents chemical oxidation by oxygen in normal air. An example is the rancidification (caused by oxidation) of edible oils. In food packaging, inert gases are used as a passive preservative, in contrast to active preservatives like sodium benzoate (an antimicrobial) or BHT (an antioxidant).
Inert gases are often used in the chemical industry. In a chemical manufacturing plant, reactions can be conducted under inert gas to minimize fire hazards or unwanted reactions. In such plants and in oil refineries, transfer lines and vessels can be purged with inert gas as a fire and explosion prevention measure. At the bench scale, chemists perform experiments on air-sensitive compounds using air-free techniques developed to handle them under inert gas.