Final answer:
Iodine (I) is more reactive than Argon (Ar) because Iodine is a halogen with a nearly full outer electron shell, making it reactive, while Argon is a noble gas with a full valence shell, rendering it largely unreactive.
Step-by-step explanation:
The element that is likely more reactive between Iodine (I) and Argon (Ar) is Iodine (I). Iodine is a member of the halogens which are found in Group 17 of the periodic table. Halogens are highly reactive nonmetals because they are one electron short of a full valence shell, making them eager to gain that last electron through chemical reactions. In contrast, Argon is part of the noble gases located in Group 18. Noble gases are known for having their energy orbitals full, which makes them very unreactive as they already have a complete valence shell. Therefore, Iodine (I), being a halogen, is much more chemically reactive than Argon (Ar), which is a noble gas.