Noble gases are known for their high stability and relatively low reactivity compared to other elements. This stability is attributed to the electron configuration of noble gases, particularly the filled outer electron shells.
Noble gases belong to Group 18 (VIII A) of the periodic table, also known as the "helium group" or "noble gases group." Their electron configurations follow a pattern where the outermost (valence) electron shell is completely filled. Here are the electron configurations and the number of valence electrons for the noble gases:
- Helium (He): 1s² (2 valence electrons)
- Neon (Ne): [He] 2s² 2p⁶ (8 valence electrons)
- Argon (Ar): [Ne] 3s² 3p⁶ (8 valence electrons)
- Krypton (Kr): [Ar] 4s² 3d¹⁰ 4p⁶ (8 valence electrons)
- Xenon (Xe): [Kr] 5s² 4d¹⁰ 5p⁶ (8 valence electrons)
- Radon (Rn): [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁶ (8 valence electrons)
All noble gases have 8 valence electrons except for helium, which has only 2 valence electrons. This filled outer electron shell (except for helium's case) provides a high level of stability, making noble gases relatively unreactive under normal conditions. It is this stability that contributes to their limited chemical reactivity, as they have little tendency to gain, lose, or share electrons with other elements.