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2. s-Block Elements eLearn.Punjab

10. When acetylene is passed over strongly heated
lithium, it does not produce lithium acetylide, but other
alkali metals form the corresponding metallic acetylides.

2Na(s) + C2H2(g) → Na+C− ≡ C−Na+ + H2(g)

Sodium acetylide

11. Lithium has low electropositive character, thus its carbonate and
nitrate are not so stable and therefore decompose giving lithium oxide.
Carbonates of other alkali metals do not decompose. Decomposition of
lithium nitrate gives different products than the nitrates of other alkali
metals.

Li2CO3 (s) → Li2O(s) + CO2 (g)

4LiNO3 (s) → 2Li2O(s) + 4NO2 (g) + O2 (g)

2NaNO3 (s) → 2NaN O2 (s) + O2 (g)

12. Lithium hydroxide when strongly heated , forms lithium oxide
but the other alkali metal hydroxides do not show this behaviour.

2LiOH Red hot→ Li2O(s) + H2O(l)

13. Lithium reacts with nitrogen to form nitride, while the
other members of the group do not give this reaction.

6Li(s) + N2(g) → 2Li3N(s)

14. Lithium chloride has an exothermic heat of solution, whereas
chlorides of sodium and potassium have endothermic heats of solution.
15. Lithium carbide is the only alkali metal
carbide formed readily by the direct reaction.

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