Identify the correct statements from the following: (a) Alkali metals are strong reducing agents. (b) KO2 is a diamagnetic oxide. (c) Lithium chloride exists as LiCl. 2H2O
Alkali metals are strong reducing agents because after the removal of the only valence electron (ns1) they can gain the electronic configuration of noble gases (n−1)p6, that is more stable electronic configuration. KO2 is paramagnetic oxide due to the presence of 1 unpaired electrons. The number of electrons present is 17 where the sixteen electrons are from two oxygen atoms and one from the negative charge (O2−). Its molecular orbital configuration can be written as σ1s2σ×1s2σ2s2σ×2s2σ2pz2π2px2=π2py2π×2px2=π‌×2py1σ×2pz0. So, statement (B) is wrong. The hydration enthalpies of alkali metal ions decrease with increase in ionic sizes. Li+>Na+>K+>Rb+ Li+has maximum degree of hydration and for this reason, lithium salts are mostly hydrated, e.g. LiCl⋅2H2O.