Position of nobel gases in the periodic table

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Position of nobel gases in the periodic table:

The inert gases were not discovered at the time when Mendeleef gave his periodic table. He also could not imagine the presence of such elements devoid of chemical reactivity and thus left no place for these elements in his periodic table. As these elements are chemically inert, they should be placed in between the highly electronegativity halogens (VIIA) and highly electropositive alkali metals (IA), I.e., in the zero group. Further, it has been found that all these elements have fully filled stable electronic configuration, i.e., they have no tendency either to lose, gain or share electrons with the atoms of other elements. In other words, their valency is zero. Therefore, they have assigned zero group in the periodic table. Zero group is also numbered as group 18 in the modern periodic table. Basing upon their electronic configuration, it has been found that expect helium all other inert gases have eight electrons in their valence shell (ns²np⁶). As they have eight electrons in the valence shell and last electron enters the p-subshell, they should be placed in (8+10)=18 group of the periodic table. Thus, the nobel gases in the modern periodic table is placed in zero group 18 of the periodic table.

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