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[24] [56] (On the other hand, flerovium, despite being in group 14, is predicted to be unusually volatile, which suggests noble gas-like properties.) [57] [58] The noble gases—including helium—can form stable molecular ions in the gas phase. The simplest is the helium hydride molecular ion, HeH +, discovered in 1925. [59]
1.4 Phase changes and critical properties. 2 Atomic properties. 3 Abundance. 4 Economic data. 5 References and notes. Toggle the table of contents. Noble gas (data page)
The noble gases (helium, neon, argon, krypton, xenon and radon) were previously known as 'inert gases' because of their perceived lack of participation in any chemical reactions. The reason for this is that their outermost electron shells (valence shells) are completely filled, so that they have little tendency to gain or lose electrons.
From left to right in the periodic table, the nonmetals can be divided into the reactive nonmetals and the noble gases. The reactive nonmetals near the metalloids show some incipient metallic character, such as the metallic appearance of graphite, black phosphorus, selenium and iodine. The noble gases are almost completely inert.
Before 1962, argon and the other noble gases were considered to be chemically inert and unable to form compounds; however, compounds of the heavier noble gases have since been synthesized. The first argon compound with tungsten pentacarbonyl, W(CO) 5 Ar, was isolated in 1975. However, it was not widely recognised at that time. [30]
Radon is a member of the zero-valence elements that are called noble gases, and is chemically not very reactive. The 3.8-day half-life of 222 Rn makes it useful in physical sciences as a natural tracer. Because radon is a gas at standard conditions, unlike its decay-chain parents, it can readily be extracted from them for research. [19]
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The elements in a group have similar physical or chemical characteristics of the outermost electron shells of their atoms ... d Group 18, the noble gases, were not ...