Why do the members of Group 1 react by losing an electron, but the members of Group 17 react by gaining an electron?

1 Answer
Jun 23, 2018

Answer:

Because metals are reducing....

Explanation:

And non-metals are oxidizing...

Consider the electronic structure of the alkali metals. These have a SINGLE valence electron...and are readily oxidized..

#Na(s) rarr Na^+ + e^(-)#

On the other hand, non metals, i.e. dioxygen, difluorine, and dichlorine, have high unshielded nuclear charge, and certainly this is reflected by the atomic radii...WHICH DECREASE ACROSS a Period, from left to right as we face the Table.....

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And thus the halogens have high UNSHIELDED nuclear charge, and are very readily reduced .... to give FORMALLY LARGER ANIONS, i.e. #O^(2-)#, #S^(2-)#, and #X^-#...

#1/2X_2 + e^(-) rarr X^-#

And so the relative reactivities owe to atomic structure, which is certainly reflected by the Periodic Table....