Thursday, August 27, 2020


                 Some chemical elements exist in two or more different forms in the same physical state known as Allotropes of elements. In greek "allos" means another and trope means change. 

For example: Carbon exists as diamond and graphite. This phenomenon is called allotropism and the different forms of elements are called allotropes.

Allotropes of some elements:


Carbon           -- Diamond, Graphite, Amorphous carbon, Fullerenes, Graphene, Carbon nanotubes.

Oxygen          -- Dioxygen, Ozone, Octaoxygen.

Selenium        -- Red selenium, Gray selenium, Black selenium, Monoclinic selenium.

Phosphorus    -- White phosphorus, Red phosphorus, Violet phosphorus, Black phosphorus, Scarlet                                          phosphorus.

Sulphur          -- Rhombus sulphur, Monoclinic sulphur.

Metalloids :

Tellurium     -- Amorphous tellurium, Crystalline tellurium.

Boron.          -- Amorphous boron,  ⍺ - rhombohedral boron, β - rhombohedral boron, 𝛾 - orthorhombic                                boron, ⍺ - tetragonal boron, β -tetragonal boron.

Germanium  --  ⍺ - germanium, β - germanium.

Arsenic         -- Yellow arsenic, Gray arsenic, Black arsenic.

Antimony     --  Yellow antimony, Black antimony, Blue-White antomony.

Silicon.         --  Amorphous silicon, Crystalline silicon.


Tin        --  Gray tin, White tin, Rhombic tin, Sigma tin.

Iron      --  Ferrite, Austenite.

cobalt   --  ⍺ - cobalt, β - cobalt.    


Wednesday, August 26, 2020

Reduction Of Metal Oxides

          Extraction of metals from their respective ores. In this method we can get metal oxides again we adding some reducing agent and heated up. It will give pure metals.


     Smelting is a process of reduction of metal oxide to metal by carbon, carbon monoxide, or aluminum. In this metal oxide is heated above the melting point of the metal.


Oxide of ion can be reduced by carbon monoxide.

Fe2O3  +  3CO  ———>  2Fe   +   3CO2            

         Limestone ( CaO ) is a basic flux. Silica gangue present in the ore in its acidic nature. The limestone combines with silica gangue to form calcium silicate( slag ). 

  CaO    +      SiO2      ———>    CaSiO3

(Flux)       ( Gangue)                      (Slag)

             The concentrated ore ( copper pyrite ) heated in a reverberatory furnace. It will form metal sulphides FeS and Cu2S. Both are soluble and form a copper matte.

2CuFeS2  +  O2  ———>  2FeS  +  2Cu2S  +  2SO2

FeS oxidized to FeO.

FeS  +  O  ———>   FeO   +   SO2

Now the ferrous oxide ( flux ) reacted with the silica ( gangue ) to form ferrous silicate  ( slag ).

    FeO     +       SiO2       ———>      FeSiO3

  (Flux)        (  Gangue)                      (Slag)

The remaining copper sulphide is further oxidised to its oxide to form the metallic copper.

Cu2S  +  3O2  ———>  2Cu2S  +  2SO2

2Cu2O  +  Cu2S  ———>  6Cu  +  SO2

This metallic copper  has blistered appearance due to the evolution of   SO2  gas. This copper is called Blistered copper.

Reduction By Carbon:

        In this method oxide ( ZnO ) ore is mixed with coal ( Coke ) and heated strongly in a furnace. This process only applied to the metal which do not form carbides with carbon. 

Examples :

ZnO  +  C  ———>  Zn  +  CO

Mn3O4  +  4C  ———>  3Mn  +  4CO

Cr2O3  +  3C  ———>  2Cr  +  3CO

Reduction Of hydrogen;

              This process only applied to the metal which have less electro -positive character than hydrogen.

Ag2O  +  H2  ———>  2Ag  +  H2O

Fe2O4  +  4H2  ———>  3Fe  +  4H2O

Reduction By Metal:

B2O3  +  6Na  ———>  2B  +  3Na2O

Rb2O3  +  3Mg  ———>  2Rb  +  3MgO

TiO2  +  2Mg  ———>  Ti  +  2MgO

In this process metal oxides reduced by metal.

Conversion Of Ores Into Oxides

        Oxygen is more electronegative than other elements. So it is easier for oxides to accept an electron pair and get reduced.

Calcination :

        Calcination is the process of heating a substance in a limited supply of air or oxygen. During this process the water of crystallization present in the hydrated oxide escapes as moisture. Due to the thermal energy (Heat) we can change their chemical state and turn them into oxides. The hydroxides and carbonates are usually converted to oxides through this process. 

Fe2O3.3H2O  ———>  Fe2O3  +  3H2O

CaCO3  ———>  CaO  +  CO2

PbCO3  ———>  PbO  +  CO2

ZnCO3  ———>   ZnO  +  CO2

MgCO3.CaCO3   ———>  MgO  +  CaO  +  2CO2

Al2O3.2H2O  ———>  Al2O3  +  2H2O

Roasting :

      Roasting is the method of heating sulphide ore to a high temperature in the presence of air. In this method the concentrated ore is oxidized by heating it with excess of oxygen in a suitable furnace with in the melting point of the metal. the oxygen in the air reacts with the sulphide ores to give us oxide.

Example ;

2Zns  +  3O2  ———>  2ZnO  +  2SO2

2Cu2S  +  3O2   ———>   2Cu2O  +  2SO2 

2PbS  +  3O2  ———>  2PbO  +  2SO2

       Roasting also removes impurities such as arsenic, sulphur, phosphorus by converting them into their volatile oxides.

Examples :

4As  +  3O2  ———>  2As2O3

S8  +  8O2  ———>  8SO2

P4  +  5O2  ———>  P4O10

Extraction of Metals

                  The concentrated ores are still in their original oxides, sulphide or halides forms. To obtain pure metals from these chemicals, it is better convert the metal compounds into oxides. Oxides of metals can be reduced easily and pure metal can be obtained. Therefore the two main steps of extraction of metals are,

  1. Conversion of ores into oxides
  2. Reduction of metal oxides
Conversion of ores into oxides:

  • Roasting 
  • Calcination 
Reduction of metal oxides:
  • Smelting
  • Reduction by carbon
  • Reduction by hydrogen
  • Reduction by metal

Friday, August 14, 2020

Metals and their ores and chemical formula


Minerals and Ores


             A mineral is a solid chemical compound that occurs naturally in pure form. Which contains the metal in free state or in the form of compounds like oxides, sulphides, halides, carbonates......etc.

Ores :

         Ores are mineral from which metal are extracted conveniently and profitably. these ores contains good percentage of metal. hence all ores are minerals but all minerals are not ores.

Thursday, August 13, 2020

General characteristics of p-block elements

 General characteristics:

* Electronic configuration:

                     The general electronic configuration of p-block elements is ns2 np1-6 . The general electronic configuration of helium is  1s2 .

                        Group 13    ns2 np1                        

                        Group 14    ns2 np2                       

                        Group 15    ns2 np3                       

                        Group 16    ns2 np4                      

                        Group 17    ns2 np5                        

                        Group 18    ns2 np6    ( except helium )

* Metallic character :

  • The non-metallic character of elements decreases down the group.
  • In general nonmetals have higher ionisation energy and higher electronegativity than metal.
  • Most of them form covalent compounds.
  • Most of the elements show negative ( except some metals ) as well as positive oxidation states ( except fluorine ).

Thursday, August 6, 2020

Dancing naphthalene ball

This video describes naphthalene balls dancing.
You will need,
  • Citric juice ( lemon juice )
  • Baking soda
  • Water 
  • Beaker
  • Naphthalene balls
       Baking soda (sodium bicarbonate ) reacts with lemon juice ( citric acid ) chemical reaction takes place, carbon dioxide gas evolved. The carbon dioxide gas form on the surface of a naphthalene ball, it rises to the surface. This will provide the dancing effect.
                       3NaHCO+ C6H8O7 ———> Na3C6H5O7 + 3H2O + 3CO2

For more reaction details check my previous blog.
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Elephant toothpaste

This video describes how to make a elephant toothpaste.
You will need,
  • Soda bottle
  • 1/2 cup hydrogen peroxide ( we used 3% )
  • 1 tablespoon yeast
  • 3 tablespoon warm water
  • Liquid dish soap
  • Food color ( optional )
  • Safety goggles 
  • Do with adult help
        Elephant toothpaste is a foamy substance caused by the rapid decomposition of hydrogen peroxide using yeast and warm water. The yeast acted as a catalyst , a catalyst is used to speed up a reaction. Yeast broke down hydrogen peroxide into water and oxygen. It created lots and lots of bubbles. If you touch the bottle it will be warm because of exothermic reaction. Exothermic reaction is a chemical reaction that releases energy through heat or light.

                     2H2O2 ———> 2H2O + O2

How rapidly the reaction proceeds will depend on the concentration of hydrogen peroxide.


Hydrogen peroxide can irritate skin and eyes.And be sure to wear safety goggles. Please do with adult help.

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How to inflate balloon with baking soda and vinegar

This video describes how to inflate a balloon with baking soda and vinegar. You will need baking soda, vinegar, soda bottle, and balloon.

Reaction :
       When the vinegar ( acetic acid ) contact with the baking soda ( carbonate ) a chemical reaction takes place, creating carbon dioxide gas. This carbon dioxide gas inflate the balloon. 🎈 

                   NaHCO3 + CH3COOH ———> CH3COONa + H2O + CO2


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