Metals and Non-metals

Introduction

Metals and non-metals are an essential part of our daily life. There are at least 118 elements known today; among these, more than 90 metals, 22 non-metals, and a few metalloids are found. Metals are usually solid in nature with rare exceptions- lead( liquid metal). Non-metals vary in their properties. Metal is a solid material which conducts heat and electricity, feels hard, shiny, malleable, fusible, and ductile. Non-metal is a substance that does not exhibit properties of metals such as hardness, lustre, malleability, ductility and the ability to conduct electricity. The non-metals are the substances with a tendency to accept electron hence they are electronegative in nature. Some of the metals are Sodium (Na), potassium (K), magnesium (Mg), aluminium(Al), calcium(Ca), Iron(Fe), Barium(Ba) . Non-metals are Oxygen(O), hydrogen(H), nitrogen(N), sulphur(S), phosphorus(P), fluorine(F), chlorine(Cl), bromine(Br), iodine(l) and many more . Some of the important metals and non-metals are explained as under.

 

Properties of metals

The easiest way to start grouping the substances is by comparing their physical properties. Metals are unique with characteristics like illustriousness, malleable, ductile, good conductors of heat and electricity. The following are some of their physical properties.

 

Chemical Properties of Metals

 Metals are electropositive elements because they can form positive ions by losing electrons. Non-metals are electronegative elements because they can form negative ions by gaining electrons. Some of their chemical characteristics are:

Reaction of Metals with Oxygen :

When metals react with oxygen they form metal oxides, but the rate and intensity of reaction vary with different metals.  For example, if the sodium metal is exposed to air it catches fire quickly hence it is stored in kerosene oil. As all the metals have different reactivity, so they combine with oxygen at different temperatures. Some of the common metals reacting with oxygen are as explained below.

Sodium metal reacts with oxygen of air at room temperature to form basic sodium oxide.

               4Na      +      O2                 (2Na2O)                            
             (Sodium )      (Oxygen)  → (Sodium oxide)

 

When you heat magnesium metal, it burns in the open air to give magnesium oxide. 

               2Mg      +      O2   → 2MgO
          (Magnesium)  (Oxygen) (Magnesium oxide)                  

Zinc metal is not very active as it burns in the air only when a strong heat is applied to form zinc oxide. 


               2Zn      +      O2   →  2ZnO
            (Zinc)      (Oxygen)     (Zinc oxide)          

  Most of the metal oxides are not soluble in water, but some metal oxides gets easily dissolved in water to form metal hydroxides (or alkali). For example, oxides of sodium and potassium dissolve in water to form sodium hydroxide and potassium hydroxide respectively as follows.

  Na2O      +           H2O →    2NaOH
  (Sodium oxide )      (Water)       (Sodium hydroxide )                                   

 K2O      +                   H2O  →    2KOH
 (Potassium oxide)   ( Water)     ( Potassium hydroxide)

 Sulphur reacts with oxygen to form acidic Sulphur dioxide.

S      +         O2 →  SO2

(Sulphur) (oxygen )    (Sulphur Dioxide)                               

 

Metals reacting with water  : 

Metals react with water to produce metal oxide (or metal hydroxide) and hydrogen gas. But, all metals do not react with water at equal intensity. The metals which are very reactive can react even with cold water while the other metals react with hot water or with steam. For example:

  1. Sodium, potassium and calcium metal can react with cold water to produce their hydroxides and hydrogen gas.
         2Na      +      2H2O  → 2NaOH    +     H2
       (Sodium)           (Water)     (Sodium hydroxide )                

      2K      +         2H2O →  2KOH +     H2
      (Potassium)  ( Water )  (Potassium hydroxide)                    

           Ca      +      2H2O → Ca (OH)2   +  H2
          (Calcium)    (Water)    (Calcium hydroxide)                        

  1. When Magnesium, zinc and iron react with hot water, they produce metal oxide and hydrogen gas.

         Mg      +      H2O  →    MgO   +     H2
    (Magnesium) (Water )   (Magnesium oxide )                                      

         Zn      +      H2O  →    ZnO     +     H2
        (Zinc)         (Water )     (Zinc oxide )                       

         3Fe    +    4H2O  →    Fe3O4+    4H2
        ( Iron)        (Water)         (Iron oxide)                   

 Reaction of Metals with Dilute Acids :

When a metal reacts with a dilute acid then a metal salt and hydrogen gas are formed. For example Sodium, magnesium and zinc react with dilute hydrochloric acid to form their salts and hydrogen gas.       

2Na      +            2HCl   →                2NaCl    +     H2
 (Sodium) (Hydrochloric acid)  (Sodium chloride )               

      Mg      +                2HCl   →          MgCl2  +     H2
  ( Magnesium)     Hydrochloric acid   (Sodium chloride )           


   Zn      +       2HCl   →  ZnCl2   +    H2
     Zinc        Hydrochloric acid  (Zinc chloride )        

Reaction of Metals with Salt Solutions: 

When a highly reactive metal is immersed in the salt solution of a less along with less reactive metal, the more reactive metal displaces the less reactive metal from its salt solution. These reactions are called displacement reaction. For example, if a piece of copper metal is placed in a colourless solution of silver nitrate for some time, the colour of the solution becomes blue and a shining white deposit of silver metal is formed on the piece of copper. Actually, in this reaction copper metal is more reactive than silver present in the silver nitrate solution. So, copper displaces silver from silver nitrate solution to form copper nitrate and silver metal.
       Cu     +     2AgNO3   →  Cu(NO3)2     +      2Ag

     Copper     Silver nitrate       Copper nitrate         Silver
                (Colourless solution)  (Blue solution)  (White deposit)

Reaction of Zinc with Copper Sulphate Solution:

   Zn     +     CuSO4  →          ZnSO4      +               Cu

 Zinc      Copper sulphate      Zinc sulfate Copper
              (Blue solution)          (colorless solution)     (red-brown)

 

Reaction of Iron with Copper Sulphate Solution:

       Fe     +       CuSO4    →           FeSO4      +     Cu      

   Iron           Copper sulphate     Iron sulphate         Copper
                   (Blue solution)     (Greenish sol)        (red-brown)

 

Reaction of Metals with Chlorine (all metals react with chlorine to form ionic metal chlorides)

    2Na       +       Cl2   →     2NaCl
   (Sodium)    (Chlorine)   (Sodium chloride)          

            
   Ca       +      Cl2    →   CaCl2
  (Calcium ) (Chlorine) (Calcium chloride)                         

  Mg       +         Cl2  →   MgCl2
(Magnesium)   (Chlorine ) (Sodium hydrides)                   

     Zn       +       Cl2      →    ZnCl2
  ( Zinc )        ( Chlorine)    (Zinc chloride)

 

Reaction of Metals with Hydrogen:

Only a few metals like Na, K, Ca and Mg react with hydrogen to form metal hydrides.

      2Na       +       H2      →  NaH
  (Sodium )     (Hydrogen)  (Sodium hydrides)                 

   Ca       +       H2      →   CaH2
    (Calcium ) (Hydrogen ) (calcium hydrides)              
                    

 

Further reading

1      

Non-metals 

2

Alkali metals and alkaline earth metals

3

Extraction of metals

4

Periodic table

 

Questions

  1. Name the liquid metal commonly found 

  2. Distinguish between metals and non-metals

  3. Explain the characteristics of metals

  4. What is malleability?

  5. Why are metals so hard?

  6. Why metals are good conductors?

  7. What is the reaction of Metals with Salt Solutions, write equation with an example.

  8. What happens When metals react with oxygen

 

 

 



img-1


img-1


img-1

Course List