Metal Oxides

[NarutoMD]

Hi,
I have a question about Alkali metals. Why do they form variable oxides when reacted with oxygen gas? For example, lithium would form an oxide when reacted with oxygen gas but sodium would form a peroxide. And potassium and cesium would form superoxides. Any insights would be appreciated. Thank you

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[aldol16]

It has to do with thermodynamics. Nature tends towards energy minima and that means nature will form the strongest bonds it can (this is why sand is so stable and pervasive - silicon-oxygen bonds are some of the strongest known). So for bond energy reasons, lithium oxide is the best candidate for most stable configuration of bonds after reacting lithium metal with oxygen. Same for the peroxides and superoxides. These are empirical observations and thus you won't need to understand the why for the MCAT.

 

[NarutoMD]

Thanks! What you said about thermodynamics and how nature tends toward energy minima will come in handy in WTF moments.