noble gas(redirected from Group 18 element)
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Related to Group 18 element: Noble gases
Any of the elements in Group 18 of the periodic table, including helium, neon, argon, krypton, xenon, and radon, which are monatomic and with limited exceptions chemically inert. Also called rare gas.
(Chemistry) another name for inert gas1
any of the chemically inert gaseous elements of group 8A or 0 of the periodic table: helium, neon, argon, krypton, xenon, and radon. Also called inert gas.
Any of the six gases helium, neon, argon, krypton, xenon, and radon. Because the outermost electron shell of atoms of these gases is full, they do not react chemically with other substances except under certain special conditions. Also called inert gas. See Periodic Table.
Word History What makes a noble gas so noble? The noble gases are a group of six chemical elements, normally occurring in gaseous form, that do not react chemically with other elements or chemical compounds except very rarely. Helium and neon are two familiar examples. The fact that the noble gases do not mix with other elements became the basis for a comparison with nobility. The nobility—the class that rules many societies and includes royalty—usually keep to themselves and do not mix with common folk.
Any of a series of elements that are mostly inert and monatomic, for example argon and helium.
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|Noun||1.||noble gas - any of the chemically inert gaseous elements of the helium group in the periodic table|
chemical element, element - any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
Ar, argon, atomic number 18 - a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere
atomic number 2, He, helium - a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and Kansas)
atomic number 36, Kr, krypton - a colorless element that is one of the six inert gasses; occurs in trace amounts in air
atomic number 10, Ne, neon - a colorless odorless gaseous element that give a red glow in a vacuum tube; one of the six inert gasses; occurs in the air in small amounts
atomic number 86, radon, Rn - a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health
atomic number 54, Xe, xenon - a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts
gas - a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely