Answer:
Step-by-step explanation:
-We know that an atom is table if they have 8 valence electrons (like noble gases, they are stable)
-Group 1 atoms only has 1 valence electron, in order to become stable, they are desperately wanted to lose that one valence electron to become stable.
-While group 15 has 5 electrons, it is easier for them to gain 3 electrons to become 8 electrons than losing all 5 electrons.
-the same thing for group 16 has 6 valence electrons and 17 has 7 electrons. It is easier for them to gain 2 and 1 more valence electrons to become stable.
Hope this helps!