P-Block Elements and Their Compounds-II: Classification of Oxides (For CBSE, ICSE, IAS, NET, NRA 2022)

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Classification of Oxides

  • The binary compounds of oxygen with other elements (metals or non-metals) is called oxides.
  • Depending on the acid-base Behaviour of the oxides, they can be classified into the following categories:

Acidic Oxides

  • Acidic oxides are generally formed by non-metallic elements and some metals in higher oxidation states.
  • Examples of some acidic oxides are , , , , , etc.
  • These oxides combine with water to form acids and with alkalis to form salt and water.

Basic Oxides

  • Metals combine with oxygen to form basic oxides.
  • Basic oxides react with acids to form salt and water.

Amphoteric Oxides

Some metallic oxides show the characteristics of both acidic as well as basic oxides, i.e.. they react with both acids as well as bases to form salt and water. These oxides are called amphoteric oxides.

For Example, the oxides of zinc, aluminum, lead and tin.

Neutral Oxides

  • These oxides are neither acidic nor basic.
  • For example, carbon monoxide, , nitric oxide , nitrous oxide , etc.


  • Ozone is an allotrope of oxygen.
  • Ozone is prepared industrially by Siemen՚s ozonize.

Siemens Ozonize

  • In this apparatus metal electrodes are used to produce an electric field.
  • Two coaxial glass tubes are fused together at one end.
  • The outer tube has an inlet for oxygen or air and an outlet for ozone.
  • The inner side of the inner tube and the outer side of the outer tube are coated with tinfoil (T) .
  • These are connected to the terminals of an induction coil or high voltage transformer.
Siemens Ozonize
  • Pure, dry and cold oxygen or air is passed through the inlet in a slow current.
  • Electrical energy is absorbed and about 5 to 10 percent of oxygen is converted into ozone.

Structure of Ozone

  • Ozone forms a V-shaped molecule.
  • The central O atom uses hybrid orbitals for bonding.
  • The structure of ozone can be explained as a resonance hybrid of the following two structures.
Structure of Ozone

Properties of Ozone


  • Ozone is a pale blue gas which turns into blue liquid at .
  • It freezes to a violet black solid at .
  • It is ten times as soluble in water as oxygen.


Catalytic Decomposition

At ordinary temperature , it decomposes in the presence of chlorine, bromine, nitrogen pentoxide and other acidic oxides and oxides of transition metals.

Oxidizing Properties

It oxidizes black lead Sulphide to white lead sulphate

Ozone oxidizes acidified ferrous sulphate to ferric sulphate

Ozone oxidizes moist Sulphur to sulphuric acid and phosphorus to phosphoric acid.

Ozone oxidizes stannous chloride to stannic chloride.


All unsaturated organic compounds combine with ozone to form unstable compounds called ozonide՚s, e. g.

All Unsaturated Organic Compounds

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