(i)    Pure Li₂O is prepared by thermal decomposition of Li₂O₂
          450⁰C           1
Li₂O₂   →   Li₂O + 2   O₂

(ii)    Sodium oxide (Na₂O) can be prepared by any one of the following reactions :

Na₂O₂ + 2Na    →   2 Na₂O
NaOH + Na       →   Na₂O + 1  H₂
                                          2
NaNO₂ + 3Na   →  2Na₂O  + 1  N₂
                                             2
(iii)    The normal oxides of other alkali metals (K, Rb and Cs) can be prepared by similar reactions.
Li₂O and Na2O are white, K₂O yellowish white, Rb₂O bright yellow and Cs₂O orange in colour . The compounds are stable towards heat and decompose only slightly below 500⁰C.

The oxides M₂O (Li, Na, K,Rb) have the antifluorite structure. The structure is related to CaF₂ (fluorite) strucutrebut with the sites occupied by cations and anions are interchanged.

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