1. What is the common valence electron configuration for elements in Group 18 (noble gases) of the periodic table?

Common Valence Electron Configuration for Group 18 Elements

Group 18 of the periodic table is known as the noble gases, which include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). The defining feature of these elements is their complete valence electron shell, which contributes to their stability and low reactivity.

1. Electron Configuration Overview

   • Noble gases have full outer electron shells, meaning they have all the electrons they can hold in their outermost energy level, leading to a stable electronic configuration.

2. Valence Electrons in Noble Gases

   • The common valence electron configuration for the noble gases can be summarized as follows:
     • Helium (He): $1s^2$
     • Neon (Ne): $1s^2 2s^2 2p^6$
     • Argon (Ar): $1s^2 2s^2 2p^6 3s^2 3p^6$
     • Krypton (Kr): $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 4p^6$
     • Xenon (Xe): $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 4p^6 5s^2 5p^6$
     • Radon (Rn): $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 4p^6 5s^2 5p^6 6s^2 6p^6$

3. Summary of Valence Electron Configuration

   • The general form for the valence electron configuration of noble gases is given by: $\text{Noble Gas Configuration} = ns^2 \, np^6 \quad (n \text{ is the principal quantum number})$
   • This indicates that noble gases have two electrons in the 's' subshell and six electrons in the 'p' subshell of their highest energy level.

Conclusion

Thus, the common trait among Group 18 elements is their complete valence shell, making their electron configurations end in $ns^2 \, np^6$, leading to their inert behavior and minimal chemical reactivity.