Group 18 . 5 Argon Helium Krypton

Group 8A—Noble gases Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) are gases of very low reactivity. Helium, neon, and argon don t combine with any other element krypton and xenon combine with very few. 

Gases form the group 8 of the periodic table. All contain a complete outer shell of electrons. They are helium, neon, argon and krypton. 

Gold, silver, and platinum are members of a class of metals called noble metals because they are relatively unreactive. (The term noble implies a class set apart.) Other elements that appear in nature in the uncombined state are the elements in Group 8 helium, neon, argon, krypton, xenon, and radon. 

Clues to the answer to this question may be found by considering a group of elements known as the noble (or inert) gases helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). Inert means inactive or idle , and describes the chemical reactivity of these elements. They are unreactive and for this reason are said to be chemically stable. He, Ne and Ar do not react with any other elements, whereas Kr and Xe react only with highly reactive fluorine. What is it that makes them so unwilling to react ... 

The first element in Group 18, helium, has the electron configuration s, the second, neon, the configuration [He]2 2p , while the heavier elements, argon, krypton and xenon, have the electron configurations [Ng](n - According to Lewis electron octet... 

The Group 8A(18) elements are helium (He), the second most abundant element in the universe neon (Ne) argon (Ar) krypton (Kr) xenon (Xe) and radioactive radon (Rn). Only the last three form compounds [Group 8A(18) Family Portrait], The noble gases make up about 1% by volume of the atmosphere, primarily due to the abundance of Ar. 

By this time you can see a pattern develop among the ground-state electron confign-rations of the atoms. This pattern explains the periodic table, which was briefly described in Section 2.5. Consider helium, neon, argon, and krypton, elements in Group VIIIA of the periodic table. Neon, argon, and krypton have conflgnrations in which a p subshell has just fllled. (Helium has a filled s subshell no p snbshell is possible.)... 

Noble gases (Section 1 1) The elements in group VIIIA of the penodic table (helium neon argon krypton xenon radon)... 

Neon has eight valence electrons and all of them are paired, hence the valence orbitals of neon are completely filled. Therefore neon is very unreactive and does not bond with any other element. Similarly, the group 8A elements (noble gases) helium and argon are very unreactive. However, krypton and xenon may form bonds under certain conditions. 

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