Gases: inert, 29 noble

Argon is a colorless, odorless, tasteless, chemically inert noble gas that makes up about 0.93% of the Earths atmosphere. It is the third most abundant gas in the atmosphere, meaning it is more common than carbon dioxide, helium, methane, and hydrogen. 

Atoms form bonds in order to obtain a stable electronic configuration, i.e. the electronic configuration of the nearest noble gas. All noble gases are inert, because their atoms have a stable electronic configuration in which they have eight electrons in the outer shell except helium (two electrons). Therefore, they cannot donate or gain electrons. 

Ans. Group VIIIA element (also referred to as an inert gas or noble gas)... 

Radon-222 is an inert noble gas produced by alpha decay of 226Ra with a half-life of 3.85 d. The primary application of 222Rn in estuaries has been in estimating flux rates of pore waters across the sediment-water interface and the rate of gas exchange between the estuary and the atmosphere. 

From the chemical point of view, the most direct and dramatic consequence of the )3-decay is undoubtedly the sudden change of chemical identity undergone by the radioactive atom, which drastically affects all its properties, including the ability to form, or maintain, chemical bonds. If the radioactive atom is chemically combined, the change of its atomic number is often sufficient to cause the disruption of the molecule, particularly when the nuclide formed from the decay is a chemically inert, noble gas atom. Other important chemical consequences follow directly from the intrinsic physical characteristics of the nuclear transformation. 

Radon is an inert noble gas and in the natural enviromnent its most important isotopes are Ra and °Rn. Rn (half-hfe 3.8 days) is an immediate daughter nuclide of Ra, but °Rn (half-life 55 s) is a product of " Ra decay [24]. From... 

Rn is inert noble gas that does not interact biochemically with the blood or tissues. 

Each metal has the electron configuration of an inert (noble) gas plus one electron in the next higher s orbital. Thus, Na is or alter-... 

Radon is a relatively inert noble gas that does not readily interact chemically with other elements. However, radon is a radioactive element and evaluation of the adverse health effects due to exposure to radon requires a slightly different approach than other chemicals. Radioactive elements are those that undergo spontaneous transformation (decay) in which energy is released (emitted) either in the form of particles, such as alpha and beta particles, or photons, such as gamma or X-ray. This disintegration or decay results in the formation of new elements, some of which may themselves be radioactive, in which case they will also decay. The process continues until a stable (nonradioactive) state is reached (See Appendix B for more information). 

This he called the effective atomic number rule . It is now called the inert/noble gas rule , or the 18-electron rule . The latter is based on the number of outer electrons (i.e. electrons outside an [Ar], [Kr], or [Xe4f " ] core) ... 

Substances that are chemically unreactive are generally not thought to be dangerous to one s health. However, radon, a colorless, odorless, chemically inert noble gas, is considered to be a serious health risk because it is radioactive. It is believed to be the leading cause of lung cancer among nonsmokers. It has been estimated by U.S. officials that up to 8% of the annual lung cancer deaths in the United States can be attributed to indoor exposure to radon-222. 

Fig. 20 Mendeleev periodic table, displaying horizontal autoreactive elements (i.e., chlorine dimer) in respective periods (1, 2, 3...) penultimate to the vertical column of non-autoreactive noble gases. Far right column displays ideal theoretical, shell-saturated PAMAM dendrimers (G = 1, 2, 3,...) as heuristic non-autoreactive nanoscale analogs of inert, noble gas elements. In the case where G = 2, shell-saturated dendrimer structure is equivalent to argon at the atomic level...

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