Question

The S- block elements are fcharacterissed by their larger atomic sizes lower ionisation enthalpies invariable +1 oxidation state and solubilities of their oxosalts. In the light of these features describe the nature of their oxides, halides and oxosalts.

Answer 1

Due to low ionoisation energy and large atomc size , Alkali, metls form cation readily and so their compounds are ionic.
Oxides
Due to + 1 oxidation state, alkali metls form normal oxides of general formula $M_{2}O$ Only Li forms normal $L{i}_{2}O$ when heated in air . Other form peroxide and superoxide. Oxides fo alkali metals are strongly basic and are soluble in water.
The basic character of oxide increases gradually form $L{i}_{2}OtoC{s}_{2}O$ due to increased ionic character.
Halides Except lithium haldes all other alkali metal halides are ionic . Due to high polarising poower of $L{i}^{+}$ lithium halide is covalent in nature. Due to + 1 oxidation states alkali metal halides have generrtal formula MX. low ionisation enthalpy allows formation of ionic halides.
OxO salts
All alkali metals form solid corbonates of general formula $M_{2}C{O}_3$ carbonates are stable except $L{i}_{2}C{O}_3$ due to high polarising capacity of $L{i}^{+}$
which is unstable and decomposes all the alkali metals (except Li)I form solid bicarbonates$MHC{O}_3$ All alkali metals form nitrates having formula $MN{O}_3$ They are colouriess, water soluble, electrovalent compounds.