CBSE Class 11-science Answered

Lithium has a diagonal relationship with magnesium and both have similarities in some of their characteristics.
a) The atomic radius of both elements is close; lithium (152 pm) and magnesium (160 pm).
b) Both have almost similar electronegativities (Li = 1.0, Mg = 1.2)
c) Both Li and Mg are quite hard.
d) Both LiOH and Mg(OH)₂ are weak bases.
e) Lithium reacts with N₂ to form lithium nitride, while magnesium also reacts in a similar way. Other members of the group do not display this characteristic.
f) Both lithium and magnesium combine with oxygen to form monoxides. Other member form peroxides and superoxides.
g) On strong heating, the hydroxides of both metals decompose to form respective oxides.
h) When heated, the carbonates of both these metals evolve CO₂.
i) The nitrates of both lithium and magnesium evolve nitrogen dioxide and oxygen on heating.
j) Lithium hydroxide, fluoride, phosphate, oxalate and carbonate are comparable to those of the corresponding magnesium compounds. However, the solubilities are much less soluble than the corresponding sodium and potassium salts.