Question

Group 17 elements are strong non-metals, while group 1 elements are strong metals. Explain.

Answer 1

we know that the metallic character decreases from left to right.
from this we can say that groups in the beginning may posses more metallic character than the ending groups compounds.
thus,the group 1 metals are more strong metals than the elements in the 17th group.

hope it helps!!!

Answer 2

we know, all elements gain stable configuration when , elements loss or gain electrons form octet like structure.

here group 17
F , Cl, Br ,I etc are elements of group 17.

atomic no of F =9
now,
configuration of F =1s^2 ,2s^2 ,2p^5
you see Fluorine gain stable configuration when, it gain one electron,
we know,
non metal have most important character is gaining of electrons. so, group 17 are non metal .

now, group 1

Li , Na , K ,Rb Cs , Fr are the elements of group 1 .

atomic no of Li = 3
configuration of Li = 1s^2 , 2s^2 ,2p^1
you have to seen , Li gain stable configuration when , element loss one electron.

we know,
most important character of metal is lossing of electrons . so, group 1 are metal .