Question

Compare the alkali metals and alkaline earth metals with respect to

A lonization enthalpy

B Basicity of oxides

C Solubility of hydroxides

Answer 1

$\text{Comparison between alkali metals and alkaline earth metals}$

$\text{Property}$

lonization enthalpy

$\text{Alkali Metals}$

Alkali metals have lowest ionization enthalpies in respective periods.
This is because of their large atomic sizes. Also, they lose their only valence electron easily as they attain stable noble gas configuration after losing it.

$\text{Alkaline earth metal}$

Alkaline earth metals have smaller atomic size and higher effective nuclear charge as compared to alkali metals.
This causes their first ionization enthalpies to be higher than that of alkali metals. However, their second ionization enthalpies are less than the corresponding alkali metals. This is because alkali metals, after losing one electron, acquires noble gas configuration, which is very stable

Basicity of oxides

$\text{Alkali Metals}$

The oxides of alkali metals are very basic in nature..
This happens due to the hightly electropositive nature of alkali metals, which makes these oxides highly ionic. Hence, they readily dissociate in water to give hydroxide ions.

$\text{Alkaline earth metal}$

The oxides of alkaline earth metals are quite basic but less basic compared to those of alkali metals.
This is because alkaline earth metals are less electropositive than alkali metals

Solubility of hydroxides

$\text{Alkali Metals}$

The hydroxides of alkali metals are more soluble than those of alkaline earth metals.

$\text{Alkaline earth metal}$

The hydroxides of alkaline earth metals are less soluble than those of alkali metals.
This is due to the high lattice energies of alkaline earth metals. Their higher charge densities (as compared to alkali metals) account for higher lattice energies.