Members of group 18 in the modern periodic table are known as the noble gases.
They are:
The members of the group have eight electrons in their outermost orbit (except helium which has two electrons). Thus, they have a stable configuration. Group 18 elements are gases and chemically unreactive, which means they don’t form many compounds. Thus, the elements are known as inert gases. Like the other group elements, noble gas elements also exhibit trends in their physical and chemical properties. The general characteristics of noble gases are discussed below.
Neon Electronic Configuration
Characteristics of Group 18 Elements:
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Electronic configuration of noble gases:
Members of group 18 have eight valence electrons, i.e., they have eight electrons in their outermost orbit (except helium). Thus, they exhibit a stable octet configuration. But helium exhibits a duplet configuration. The general configuration of the noble gas family is given as ns2np6 (except helium which has 1s2).
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Atomic radii of noble gases:
The members of group 18 have very small atomic radii. Atomic radii of noble gases increase down the group with an increase in atomic number due to the addition of new shells.
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Ionization enthalpy of noble gases:
Noble gases have eight valence electrons, that is, they have eight electrons in their outermost orbit (except helium). Thus, they exhibit stable octet or duplet configuration. Hence, the elements of group 18 exhibit very high ionization enthalpies. Ionization enthalpy of noble gases decreases down the group due to the increase in their atomic size.
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Electron gain enthalpy of noble gases:
Members of the group have eight valence electrons (except helium). Thus, they exhibit stable octet or duplet configuration. Hence, elements of group 18 exhibit very large positive values of electron gain enthalpy.
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