10.6 Compare the alkali metals and alkaline earth metals with respect to (i) ionisation enthalpy (ii) basicity of oxides and (iii) solubility of hydroxides
(i) Ionisation enthalpy
Alkali metals have low first IE as compared to alkaline earth metals because of their large atomic size, and after losing one electron, they attain noble gas configuration. In alkaline earth metals, their first IE is higher than that of alkali metals because they have high effective nuclear charge and are small in size as compared to group 1 element. However, they have low second IE as compared to alkali metals.
(ii) Basicity of oxides:
Alkali metal oxides are more basic than alkaline earth metal oxides. this is because alkali metals are highly electropositive, which makes them highly ionic, so they readily dissociate into hydroxide ions in water compared to alkaline metals.
(iii) The solubility of Hydroxide-
Alkali metal hydroxide is more soluble in water than alkaline earth metals. This is because of the high lattice energy of alkaline earth metals.