Lithium forms monoxide only when heated in oxygen. Sodium forms monoxide and peroxide in excess of oxygen. Other alkali metals form superoxide with oxygen i.e MO_(2). The abnormal behaviour of lithium is due to small size. The larger size of nearer alkali metals also decides the role in formation of superoxides. The three ions are related to each other as follows O^(2-) overset(1/2O_(2))rarrunderset(O_(2^(2-)))overset(O_(2))rarrunderset("superoxide ion")2O_(2) Lithium does not form stable peroxide because

Lithium forms monoxide only when heated in oxygen. Sodium forms monoxi

1.	Lithium forms monoxide only when heated in oxygen. Sodium forms monoxide and peroxide in excess of oxygen. Other alkali metals form superoxide with oxygen i.e MO_(2). The abnormal behaviour of lithium is due to small size. The larger size of nearer alkali metals also decides the role in formation of superoxides. The three ions are related to each other as follows O^(2-) overset(1/2O_(2))rarrunderset(O_(2^(2-)))overset(O_(2))rarrunderset("superoxide ion")2O_(2) Lithium does not form stable peroxide because
Answer» of its SMALL size d-orbitals are ABSENT in it it is HIGHLY REACTIVE and form superoxide in place of peroxide covalent nature of peroxide Solution :DUE to small size Li shows high polarsising powerso it does not formperoxide