Using a periodic table, explain why elements in group 17 are more reactive than those in group 18.

Group 18 elements are noble gasses which are stable. They have a full valence shell so they are don't typically react too much. Group 17 only needs one more valence electron so these are most often paired with group 1 elements. Group 17 are Halogens and most often react with Alkali metals. Example: NaCl (Na group 1 | Cl group 17)

Explanation:

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide