Question

Why Li forms normal oxide and not superoxide or peroxide while rest of group 1 elements form superoxide or peroxides?

Answer 1

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Answer:
Because of the small size , Li⁺ has a strong +ve  field around it which attract the -ve charge so strongly that it does not permit the oxide anion , O²⁻ to combine with another oxygen atom to form peroxide ion , O₂²⁻ . On the other hand , Na⁺  because of its large size than  Li⁺  ion has comparatively weaker positive +ve field around it which cannot prevent o²⁻ ion to combines with oxygen atom to form peroxide ion  O₂²⁻ .  
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