Lorenzo is making a prediction. “i learned that nonmetals increase in reactivity when moving from left to right. so i predict that xenon will be more reactive than iodine.” is lorenzo correct? if so, why? if not, explain his error.

That prediction is not correct because Xenon is extremely stable; column 18 of the periodic table contains the noble gasses, which are stable because their outer-most energy levels are completely filled. Having the octet (8) of valence electrons means that the element no longer needs to lose or gain electrons to gain stability.

The column 17 elements are unstable because they only have one valence electron short of the stable octet configuration of the noble gasses.

Lorenzo is not correct. Nonmetals increase in reactivity from left to right because nonmetals on the right have more valence electrons. They need to gain fewer electrons to have a full outer shell. However, this trend only continues until group 17, because the noble gases already have a full outer shell. Therefore, their reactivity is the least of all the elements.