The binary compound of oxygen with any other elements are called oxides. For examples: CO, CO2, SO2 ,SO3 , H2O, CaO, ZnO , BaO2 etc. The compound such as Ca(OH)2, CaCO3, NaHCO3 etc. The compounds such as CaHCO3, CaCO3 etc are not termed as oxides because oxygen is in combination with more than one elements.
Classification of oxides:
On the basis of chemical behaviour and amount of oxygen oxide may be classified into the following groups:
i) Acidic Oxides( Oxides of non - metals ): Those oxides which gives acid when dissolved in water or give salts and water with base are called acidic oxides. For examples: SO2, SO3, CO2, P2O5, CrO3, etc
iv) Neutral Oxides:
Those oxides which are neither acidic or basic are called neutral oxides. For example: H2O, NO, CO, N2O, etc.
Classification based on oxygen contental
i) Normal oxides:
Those oxides which have oxygen content as required by the valence rules are called normal oxides. for eg: CO2 , SO3, PbO, MnO, P2O5, etc
Those oxide whic have greater oxygen content then that required by the valency rules are called poly oxides. It is up two types.
Those oxides which give hydrogen peroxides with dilute acid and oxygen gas with conc. H2SO4 are called peroxides. For eg: Na2O2, BaO2, Li2O2, etc.
BaO2 + H2SO4(dil) → BaSO4 + H2O2(Hydrogen Peroxide)
2BaO2 + H2SO4(conc) → 2 BaSO4 + H2O + O2
These oxides contain (O2)-2 ion having oxidation number of oxygen as -1.
Those polyoxide which don't give hydrogen peroxide with dilute acid are called dioxides. For examples: MnO2 , PbO2 etc
MnO2 + 4HCl (conc) → MnO2 + 2H2O + Cl2
2MnO2 + 2H2SO4(Conc) → MnSO4 + 2H2O + O2
iii) Sub- Oxides:
Those oxides which have lower oxygen content that required by the valency rule are called sub - oxides. For examples: N2O , PbO2 , C3O2 etc.
iv) Mixed Oxides:
Those oxides which behaves as a mixture os two simple oxides, are callled mixed oxide. FOr eg: Fe3O4, Pb3O4, Mn3O4, etc.
For eg: red lead (pb3O4) = 2 pbo (Normal Oxide)+ pbo2(dioxide)
v) Super Oxides:
Those oxides which contain higher number of oxygen in which the oxidation number of oxygen is -1/2 are known as super oxides. For eg: KO2, RbO2, CSO2, etc.