Question

Lithium forms normal oxide, sodium forms peroxide and rest all alkali metals form superoxides. Explain.

Answer 1

   Oxide ion ${ O }_{ 2 }$  and the Lithium have high charge densities and small ionic radii. Due to this, the smaller ions get packed together which forms a very stable lattice of Lithium Oxide ${ Li }_{ 2 }O$.

   Based on the stable lattice formed by packing of larger cations and larger anions, the formation of sodium peroxide, sodium oxide ${ Na }_{ 2 }{ 0 }_{ 2 }$ and superoxides of larger alkali metals like Potassium superoxide is explained.     That is, only because of the stabilisation of larger anions by larger cations the stability of peroxides and the superoxides of the alkali metals from lithium to caesium are increased.

Answer 2

Answer:

The atomic size of lithium is very small therefore it can form bond with one oxygen atom.As the size of atoms increases,it holding capacity also increases. Therefore sodium can form peroxide besides oxide and pottasium forms superoxides besides oxide and peroxide