Question

Why does xenon form stable compounds with fluorine, whereas argon does not?

Short answer

Xenon forms stable compounds with Fluorine due to their relatively similar electronegativity values, Xenon's comparatively lower ionization energy, and Fluorine's high reactivity. On the other hand, Argon, being lighter and having a greater ionization energy, does not readily form compounds with Fluorine.

Step-by-step solution

Electronic configuration of Xenon and Argon

First, we need to look at the electronic configuration of both Xenon (Xe) and Argon (Ar) to determine their position in the periodic table and the noble gas (group 18) characteristics. Xenon has an atomic number of 54 with an electronic configuration of \[1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 \] or simply, [Kr]4d^{10}5s^2 5p^6. Argon has an atomic number of 18 with an electronic configuration of \[1s^2 2s^2 2p^6 3s^2 3p^6\] or simply, [Ne]3s^2 3p^6.

Stability of noble gases

Now, we know that one of the characteristics of the noble gases is their chemical stability due to their full valence electron shells. This makes it hard for them to form compounds, as they already possess a stable electron configuration and do not need to lose or gain electrons to achieve this stability. Argon, being lighter than Xenon, has a smaller atomic radius and a greater ionization energy, making it less likely to form compounds.

Ionization energy and compound formation

However, Xenon, being a heavier noble gas and having a larger atomic radius, has a lower ionization energy than Argon. Both Xenon and Fluorine have relatively similar electronegativity values, where Xenon has an electronegativity value of approximately 2.6, while Fluorine has a value of approx. 3.98 (according to the Pauling scale). The relatively lower ionization energy of Xenon and their similar electronegativity values facilitates the formation of stable compounds between them.

The role of Fluorine in compound formation

Fluorine is a highly reactive element, having the highest electronegativity among all elements. It can therefore form stable compounds with many elements, including the noble gases. Given the right conditions (high temperatures and pressure), Fluorine can react with Xenon, breaking the stronger Xe-Xe bonds and forming stable Xe-F bonds. Some of the common Xenon-Fluorine compounds include XeF₂, XeF₄, and XeF₆.

Conclusion

In conclusion, Xenon can form stable compounds with Fluorine due to their relatively similar electronegativity values, Xenon's comparatively lower ionization energy, and Fluorine's high reactivity. On the other hand, Argon, being lighter and having a greater ionization energy, does not readily form compounds with Fluorine.