Compare and contrast the chemistry of alkali metal with that of alkaline earth metal with respect to polarising power of cations.

Options

A. Nature of oxides
B. Solubility and thermal stability of carbonates
C. Polarising power of cations
D. Reactivity and reducting power

Explanation

(a) .Nature of oxides:
Alkali metals 1. They form oxide, peroxide and superoxide, i.e. `M_(2)O,M_(2)O_(3)` and `MO_(2)` respectively.
2. Readily soluble in water to form hydroxide. They are crystalline solids.
Alkaline earth metals 1.They react slowly and form oxides and peroxides, i.e. `MO` and `MO_(2)` respectively. 2. Less soluble in water and form hydroxide. Yheir insolubility is due to their large lattice enthalpy.
(b). Solubility and thermal stability of carbonates:
Alkali metals 1. The carbonates of alkali metals are highly soluble in water. 2. The carbonates of alkali metals are highly metals are highly stable to heat.
Alkaline earth metals 1. The carbonates of alkaline earth metals are sparingly soluble in water. 2. They decompose on heating and the stability increases down the group.
(c ). Polarising power of cations:
Alkali metals
The alkali metal ions have the lowest polarising power. it is because their charge//radius ratio is very low. `Li^(o+)` has the highest polarising power among its group.
Alkaline earth metals
teh alkaline earth metal ions have high polarising power because they form bivalent ions and their charge/radius ration is higher than the alkali meats.
(d). Reactivity and reducing power:
Alkali metals 1. Alkali metals are highly reactive due to their low ionisation enthalpy and low heat of formation which decreases down the group `(darr)`. 2. The alkali metals are highly electropositive and are strong reducing agents. The `E^(Θ)` values are very high of alkali metals.
Alkaline earth metals 1. Because of their low ionisation enthalpy and high electropositive character, these metals are also very reactive but less reactive than alkali metals. 2. These metals are also strong reducing agents but less than alkali metals. They have least negative value and high enthalpy of formation.