Periodic Column Reactivities

[grizzlybear24]

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Although the Alkaline Metals have similar reactivity, why are their oxide forms variable?
Ex. Lithium forms an Oxide (Li2O), whereas Sodium forms a peroxide (Na2O2), and Potassium, Rubidium, Cesium and form superoxides (MO2)?

Thanks.

 

[grizzlybear24]

Actually, I think I may have it:

Lithium's valence e- is closer to the nucleus and therefore subject to greater attraction than its other column members, and so it takes two Li for every O to make a bond?

And progressively down the column, it gets easier to lose the valence e-. And at 4s and beyond, the reactivity with O is the same because the distance of the valence e- from the nucleus is no longer that big of a factor.

Let me know what you guys think.

 

[Dasypus]

http://www.tutorsonnet.com/chemistr...lements_group_1a_assignment_help_tutoring.htm seems to agree with you.