Classification of Oxides

You must be knowing a compound well, which is carbon dioxide. As in the process of breathing, we breathe out carbon dioxide. Apart from this it is used in the process of photosynthesis as well. As the name suggests carbon dioxide is a type of oxide. Oxygen can react with metals and non - metals to form compounds which contain oxygen and another element of metal or non-metal. Oxides can be divided into four types. 

Many elements get oxidized in air or water naturally. This is the reason many oxides are found in nature as minerals. Most of the earth crust is composed of solid oxides. As we know oxygen is a highly electronegative element, so it forms bonds with almost all elements and thus it forms stables corresponding oxides. Although this over tendency of oxygen to form oxides is sometimes harmful as well. As it corrodes metals and makes the articles made up of metals weak. In this article we will discuss all four types of oxides with examples and uses however before that we are explaining what oxides are, in brief here. 


What are Oxides? 

An oxide is a chemical compound that contains at least one oxygen atom and one other element. Dianion of oxygen is also called oxide which is represented by O-2. All oxides compounds contain at least one dianion of oxygen. Oxides are generally binary compounds composed of oxygen and another element. 

Examples of Oxides – Al2O3 – Aluminium oxide, CO2 – Carbon dioxide, SO2 – Sulfur dioxide, CaO – Calcium oxide, MgO – Magnesium oxide, Na2O – Sodium oxide etc. 


Classification of Oxides 

(image will be updated soon)

Oxides can be divided into following types on the basis of valency of another element in oxides –

  • Simple oxides 

  • Mixed oxides  (Image will be uploaded soon)

Simple Oxides – Simple oxides are made up of one metal or semimetal and oxygen. These oxides carry only that number of oxygen atoms which is allowed by the normal valency of the element or metal. 

Examples of simple oxides – H2O, MgO, CaO, SiO2 etc. 


Mixed Oxides – Mixed oxides are produced when simple oxides combine. These two simple oxides can be of the same metal (element) or different. 

Examples of Mixed oxides – Red lead (Pb3O) is mixed oxide of lead dioxide (PbO2) and lead monoxide (PbO). Another example is ferro-ferric oxide (Fe3O4) which is a mixed oxide of two simple oxides – ferric oxide (Fe2O3) and ferrous oxide (FeO).


Oxides can be divided into following types on the basis of metallic character of another element in oxides –

  • Metallic oxides 

  • Basic oxide 

  • Amphoteric oxide 

  • Non-metallic oxide 

  • Acidic oxide 

  • Neutral oxide 

(image will be uploaded soon)

Metallic Oxides – Metallic oxides are made of metal and oxygen. These are generally found in nature as minerals. These are formed by oxidation of metals.

Examples of metallic oxide – CaO, MgO, Fe3O4, BaO, ZnO etc. 


These can be classified into following two types –

  • Basic oxide 

  • Amphoteric oxide 

Basic Oxide – If an oxide reacts with water and forms a base is called basic oxide. Thus, basic oxide on reacting with water gives base. It means if we prepare a solution of basic oxide and water and dip a red litmus paper in it then it turns blue. 

Examples of basic oxides – MgO, CaO, BaO etc.


Burning of Magnesium Ribbon - When we burn magnesium ribbon it reacts with atmospheric oxygen and forms a grey colored compound which is magnesium oxide. Now when we dissolve this grey compound in water and dip a red colored litmus paper in it, then it turns red litmus into blue as it forms magnesium hydroxide on reacting with water. Reactions involved are given below –

2Mg + O2 🡪 2MgO

MgO + H2O 🡪 Mg(OH)2


Amphoteric Oxide – An amphoteric oxide is that metallic oxide which shows dual behavior. It behaves as an acidic oxide and basic oxide both. It also reacts with both bases as well as acids. 

Examples of Amphoteric oxides – Zinc oxide (ZnO)

When zinc oxide reacts with conc. Sodium hydroxide acts as acidic oxide while when it reacts with HCl it acts as basic oxide. Reactions are given below –

ZnO + 2H2O + 2NaOH 🡪 Na3Zn[OH]4 + H2

                            Acidic zinc oxide

ZnO + 2HCl 🡪 ZnCl2 + H2O

                                  Basic zinc oxide 

Another example of amphoteric oxide is Al2O3 – aluminium oxide. When it reacts with sulfuric acid it acts as a base while when it reacts with sodium hydroxide it acts as acid. Reactions are given below –

Al2O3 + 3H2SO4 🡪 Al2(SO4)3 + 3H2O

                                             Basic

Al2O3 + 2NaOH 🡪 2NaAlO2 + H2O

Acidic  Sodium aluminate

Other examples of amphoteric oxides are BeO, SnO etc. 


Non - Metallic Oxide – Non - Metallic oxides are formed by non - metal and oxygen. These are generally found in nature as gases such as carbon dioxide. These are formed by oxidation of non - metals. 

Examples of metallic oxide – CO2, SO2, P2O5, CO etc. 

These can be classified into following two types –

  • Acidic oxide 

  • Neutral oxide 


Acidic Oxides - If an oxide reacts with water and forms an acid is called acidic oxide. Thus, acidic oxide on reacting with water gives base. It means if we prepare a solution of acidic oxide and water and dip a blue litmus paper in it then it turns red. Mostly acidic oxides are oxides of non – metals but some oxides of metals with high oxidation states also possess acidic character. Thus, few metallic oxides such as CrO3, Mn2O7 etc. are also acidic oxides. 

Examples of acidic oxides – SO2, CO2, SO3 etc. 

When sulfur trioxide reacts with water, it forms sulfuric acid. Reaction is given below –

SO3 + H2O 🡪 H2SO4


Neutral Oxide – Neutral oxides are those oxides which neither show acidic properties nor basic properties. They do not form any salt when they react with acid or base. 

Examples of neutral oxides – N2O, NO, CO etc. 

This is all about Classification of Oxides, if you are looking for solutions of NCERT problems based on oxides, then log on to Vedantu website or download Vedantu Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.