Problem 31 - Chemistry: The Central Science

Question

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

Step-by-Step Solution

Answer

Xenon can form stable compounds with fluorine because of its larger atomic size, available 5d-orbitals for bond formation, and the high electronegativity of fluorine that persuades xenon to give up some of its electrons. In contrast, argon cannot form compounds with fluorine due to its smaller atomic size, lack of available orbitals for bond formation, and tightly held valence electrons by the nucleus.

Step 1: Electronic Configuration of Noble Gases

Noble gases are the elements in Group 18 of the periodic table. They are known for their full valence electron shells, which makes them chemically inert and stable. The electronic configuration for xenon (Xe) and argon (Ar) are as follows: Xenon (Xe): \(1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6 4d^{10} 5s^2 5p^6\) Argon (Ar): \(1s^2 2s^2 2p^6 3s^2 3p^6\) Their full valence electron shells make it unfavorable for them to form compounds as they already have a stable electronic configuration. However, some noble gases can form compounds under certain conditions.

Step 2: Inertness and Reactivity of Xenon and Argon

Generally, noble gases are inert due to their highly stable electronic configurations. In the case of argon, there are no available d-orbitals for bond formation, making it extremely inert in forming compounds. However, for xenon, it can accommodate electrons in the energy level of the 5d-orbitals. The larger atomic size of xenon compared to argon makes its valence electrons less tightly held by the nucleus. This leads to a higher possibility of xenon reacting with highly electronegative elements such as fluorine.

Step 3: Forming Compounds with Fluorine

Fluorine is the most electronegative element on the periodic table, so it has the most significant tendency to attract electrons. Given the right conditions, fluorine can form compounds even with the relatively inert noble gases. The high electronegativity of fluorine can persuade xenon to give up some of its electrons to form chemical bonds. On the other hand, argon's electrons are held too tightly by the nucleus to react with fluorine.

Step 4: Stability of Xenon-Fluorine Compounds

Xenon can form several stable compounds with fluorine, such as XeF2, XeF4, and XeF6. The electronegativity difference between xenon and fluorine is significant enough to create strong covalent bonds. Moreover, xenon's ability to utilize its 5d-orbitals allows these compounds to have stable electronic configurations. In conclusion, xenon forms stable compounds with fluorine because of its larger atomic size, available orbitals for bond formation, and the high electronegativity of fluorine. In contrast, argon is unable to form compounds with fluorine due to its smaller atomic size, lack of available orbitals for bond formation, and a stronger hold on its valence electrons by the nucleus.