Question

Most basic oxidein s block element

Answer 1

Oxides

Basic Oxides

The oxide ion is a very strongly basic anion due to its very small size and high charge. Since hydroxide ion is the strongest base that can persist in water, the oxide ion reacts quantitatively with water to generate hydroxide ions. This is an example the leveling property of very strong bases.

As predicted by the generalized solubility rules, only those metal oxides of the nonacidic and feebly acidic cation dissolve in water. The dissolution is highly exothermic generating the hydroxide of the cation. These aqueous solutions are strongly basic. Metal oxides which exhibit this behavior are termed basic oxidesbecause they act as bases. The oxides of nonacidic cations are so water reactive that they are seldom seen. These oxides cannot be prepared by dehydrating the hydroxide at high temperature. 

The oxides of feebly acidic cations are more common. Lime, CaO is an example. Lime can be prepared comercially by the thermal decomposition of limestone.


The oxides of feebly acidic cations react exothermically with water producing the hydroxide.

The hydroxides of feebly acidic cations are not deliquescent.

The oxides of weakly acidic cations and moderately acidic cations are insoluble in water. These oxides do not introduce significant amounts of O2- ion into the solution so hydroxide ions are not produced. Although these oxides do not significantly alter the pH of the water, they are still bases and neutralize strong acids.

FeO + 2 H3O+(aq)  Fe2+ (aq) + 3 H2O