Simple Oxides

A binary compound of oxygen with another element is called an oxide. Oxides can be classified into:

a. Acidic oxides    b. Basic oxides    c. Amphoteric oxides    d. Neutral oxides

a. Acidic oxides : An oxide which dissolves in water to give an acid, or reacts with a base to give a salt, is called an acidic oxide. For example $\mathrm{SO_2}$, $\mathrm{SO_3}$, $\mathrm{CO_2}$, $\mathrm{N_2O_5}$, $\mathrm{Cl_2O_7}$ etc.

Generally, oxides of nonmetals are acidic oxides.

b. Basic oxides : An oxide which dissolves in water to give a base, or reacts with an acid to give a salt, is called a basic oxide. For example $\mathrm{Na_2O}$, CaO, BaO etc.

c. Amphoteric oxides : The oxide which reacts with a base as well as with an acid to give a salt is called an amphoteric oxide. For example, $\mathrm{Al_2O_3}$:

$\mathrm{Al_2O_{3(s)} + 6NaOH_{(aq)} + 3H_2O_{({\it l})} \longrightarrow 2Na_3[Al(OH)_6]_{(aq)}}\ \text{(Acidic behaviour)}$ …