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  • Greek word 'Halos': sea salts and 'gen': producer.
  • Belongs to the group of the periodic table.
  • Eg:
  • Astatine is a radioactive element.
  • Fluorine is the most reactive and called super halogen.
  • Iodine occurs in petroleum oil.
  • Outermost configuration is .
  • Exists as diatomic molecules containing single covalent bonds.
  • Order of I.E = .
  • Order of Electro-negativity = .
  • Order of Electro-affinity = .
  • Order of Reactivity = .
  • Oxidizing Power= .
  • Order of Melting point= .
  • Order of Atomic Radii= .
  • Order of Bond dissociation energy=.
  • They occur in combined form.
  • State: and =Gases, =Liquid and =Solid.

=  Fluospar

=Rock salt

= Slyvine


= Cryolite


  • Oxidation state

-varies from to .- form most no. of oxides.

  • Least stable = (Super Halogen).
  • Most stable =

Preparation of Halogens:

  1. =It can only prepared by electrolytic oxidation of    but not by chemical oxidation.

i.e. By electrolysis of in presence of .

At Cathode:

At Anode:

  1. General Preparation of and .

-These are prepared by heating with Conc.H2SO4 and.


  1. Preparation of without heating :

For this is treated with .

  1. Manufacture of Bromine using Carnalite:

-Carnalite is double salt of and it contains impurities and .

  1. Manufacture of iodine using sea weeds:

-Seas weeds contain impurities and .Iodine is obtained by heating these impurities with and .

  1. Preparation of Iodine using chili salt petre.

    Chile salt petre contains impurity caliche.

Chemical Properties:

1)Reaction with hydrogen: It gives acid. Eg:

2)With Metals:

Halogens combine with metal  forming their halides.

3)With non metals:

Halogens combine with non metal forming their halides.

4)With alkali:

-Similar reaction with and as

5) Oxidising Property

a) oxidizes to .

b) is oxidized by halogen .

c) is oxidized to .

d) is oxidized to .

e) is oxidized to

f) to .

 6) Reaction of with slaked lime :


  1. To sterilize water.
  2. As a bleaching agent.
  3. Iodine to make antiseptic solution.
  4. for the preparation poisonous gases like Phoshene ,Mustard gas, Tear gas,etc.
  5. for preparation of bleaching powder and the bleaching action of is due to oxidation and is permanent.


-Carnalite is ore of Mg and is salt of Cl.

-Carnalite is used to manufacture bromine.

Hydrogen Halides


  • State: =Liquid (due to bond), =Gases.
  • Colour: Colourless in liquid state and white crystalline in solid state.
  • Highly soluble in water.
  • Order of Melting Point:
  • Order of Stability: .
  • Order of Ionic character : .
  • Order of Reactivity and reducing action : .
  • Order of Dipole Moment: .
  • Order of Bond Length: .
  • Boiling Point:


  1. Preparation of:


  1. Preparation of :


-This is also dry test for .

  1. For and

Note: - and can also be prepared by heating Phosphorous, Halogen and Water.

Chemical Properties:

1)Oxidation by air and are oxidized to and .

But is not oxidized.

2)Reducing character

    a) With acidified :

b) With acidified :

c) With :

3) Test reaction :

Silver Nitrate taste is carried out.

= no ppt                   = Pale yellow ppt

    =White ppt            = Yellow ppt



-Used to make Aqua regia.

-Used as lab reagent.


-used to prepare that are used in photography and medicine respectively.


-Used as reducing agent.

-Used to make for photography.


-Used to make itching glass

Oxyacids of Halogens:

  • Fluorine forms only one oxyacid, hypofluorous acid .
  • Other halogens forms several oxyacids of types.

Types and their oxidation number:

-Hypohalous acid =

-Halous acid =

-Halic acid =

-Perhalic acid =


  • Acidic Strength:

i) Same Halogen:

ii) Different Halogen:

(electro-negativity decreases order )

Thermal Stability of Oxyacid:

  • Oxidizing Power: