Programmes/ Content/ Chemistry



  • 'Hydro' means Water and 'gene' means producer.
  • Symbol:
  • Electronic configuration:
  • Isotopes: Protium(), Deuterium() and Tritium ().
  • Most abundant element of universe and third most abundant element on earth.
  • Resembles both alkali metal and halogen so, its position in the periodic table is controversial.
  • Discovered by Henry Cavendish.
  • Hydrogen is a non-metal.
  • Hydrogen is lightest element in periodic table.
  • Hydrogen has a negative oxidation state in .

Preparations of Hydrogen:

1) By using non oxidizing acids:Eg:

2) Using Alkali:

Amphoteric metals such as etc can produce from alkali.

3) Using Water:

i) Alkali metal and Calcium  can produce from cold water.

ii) can produce from hot water.

iii) can produce from steam.

4) By Hydrolysis of Metal hydride:


5) Electrolysis of Water:


6) Bosch Process:

By passing steam over red hot coke or coal.

Different Form of Hydrogen

Atomic Hydrogen:

i) It is form by thermal dissociation of molecular hydrogen.

i.e By passing gas through electric arc.

ii) It is Highly unstable.

iii) It is stronger reducing agent than nascent hydrogen.

iv) Formation of molecular hydrogen from atomic hydrogen is an exothermic process.

iv) Formation of atomic hydrogen from molecular hydrogen is an endothermic process.

v) It has very short half life period.

Nascent Hydrogen( newly born):

 i) Atomic form of hydrogen produced during chemical reactions.

ii) It is also unstable but less energetic than atomic hydrogen.

iii) It is powerful reducing agent than ordinary diatomic hydrogen.

Ortho and Para Hydrogen:

Ortho hydrogen:

  1. Protinic spin is in same direction
  2. At ordinary temperature ortho form is .
  3. On lowering temp. ortho is slowly converted to para hydrogen.

Para Hydrogen:

  1. Protinic spin is in opposite direction.
  2. At ordinary temperature para form is .
  3. At ordinary temperature of ortho become maximum.

Isotopes of Hydrogen:

-Isotopes are the different atoms of same elements which have same atomic number but different mass number.

1) Protium :

  • proton= , electron=, neutron=
  • Abundance =
  • Most abundant and stable isotopes.
  • It is the ordinary hydrogen.
  • Molecular Formula:
  • Nuclear spin:

2) Deuterium :

  • proton=, electron=, neutron=
  • Abundance =
  • It is called heavy hydrogen.
  • Molecular Formula:
  • Nuclear spin:

3) Tritium:

  • proton=, electron=, neutron=
  • Abundance =
  • Radioactive hydrogen emitter.
  • Molecular Formula:
  • Nuclear spin:


-Binary compound of hydrogen with metals and non-mental.

-The general formula being . where M=Metal, H=Hydrogen, x=no. of H-atom.

a) Ionic hydrides ( Saline Hydrides):

-Hydrides of more metals than hydrogen.


Except : and ---> (Covalent)

-Thermal stability decreases with increase in size of cation.


b) Molecular or Covalent hydrides:

-Hydrides of non metals.

-Acidic nature:

Types of Oxides

 1) Acidic Oxides:

-Oxides of non metals are acidic in nature and when dissolved in water gives acid.


Note: -Some oxides of transition metals are acidic :

2) Basic Oxides:

-Oxides of metal are basic in nature.

-Eg: etc

3) Amphoteric Oxides:

-Metallic oxides which shows both acidic as well as basic properties.

-Eg: .

4) Neutral Oxides:

-Oxides which shows neither acidic nor basic properties.


5) Peroxides:

-Metallic oxides which give hydrogen peroxides with acid.

-In this oxide oxidation number of oxygen is

-Eg: etc

6) Super Oxides:

-The oxidation number of oxygen in such oxide is .

-It gives hydrogen peroxide and oxygen gas on reaction with acid.

-Eg: .

7) Compound or Mixed Oxides:

-Oxides which is the mixture of two oxides.



  • Water is the most common of all the solvents.
  • Water exists in all three physical sates.
  • Sources: Ponds, lakes, rivers, ocean, rain.
  • Geometry of water : Tetrahedrol or Angular shape
  • Hybridization :
  • Bond angle :
  • Dipole moment of water molecule :

Types Of Water:

a)Hard Water

- Water that does not produce lather with soap.

-It is hard because of presence of soluble bicarbonates, sulphates, chlorides and nitrates of calcium and magnesium in water.

b) Soft water

-It produces lather with soap.

Types of Hardness

a)Temporary Hardness  

-It is due to presence of bicarbonates of Calcium and Magnesium.


Removal of Temporary hardness:

i) By Boiling:

ii) By Clark’s process:

-Slaked lime is added.

b) Permanent Hardness

-It is caused by the presence of chlorides and sulphates of calcium and magnesium.

- Permanent Hardness is also called non carbonate hardness.

-It is removed by adding washing soda.

Removal of both type of Hardness

i)By adding Chalcogen:

- It is sodium hexametaphosphate and removes and ion of hardwater as complex ion.

     =Sod. Hexa metaphosphate

ii) By Permuit process:

-Sodium Zeolite is used. Sodium Zeolite is Sodium Aluminium Silicate.It is regenerated by passing solution Of .

-In this process, Sodium ion is exchanged with and .

iii) By the use of ion exchange resin:

a) Cation Exchanger:

-Organic polymer having acid group.Exchanges all cation  water with ion of resin.

b) Anion Exchanger:

-Organic polymer and contains (RNH3OH). Exchanges all anion of  water with ion of resin.



-Ozone is allotrope of oxygen. It dissolves in turpentine oil.

-It is prepared by subjecting silent electric discharge on pure and dry oxygen.