Quick Revision: Hydrogen | Chemistry Class 11 - NEET PDF Download

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Most abundant element of the universe, which was first prepared by Cavendish by the action of acids on
certain metals. Its name hydrogen was proposed by Lavoisier because it produces water when burnt in
oxygen. Hydrogen is the lightest element which is found in nature both in free state and in combined state.
Position of hydrogen in the Periodic Table
The electronic configuration of hydrogen is 1s
1
, due to which it shows resemblance with alkali metals as well
as halogens.
Resemblance with Alkali Metals
1. Its electronic configuration is similar to alkali metals.
2. It is a good reducing agent like alkali metals.
3. It can lose one electron to form H
+
 ion like alkali metals.
4. It shows +1 oxidation state like alkali metals when bonded to non-metals.
Resemblance with Halogens
1. It is a non-metal.
2. It forms diatomic molecule.
3. It is gas like F
2
 and Cl
2
.
4. It can gain one electron to form H
–
 ion.
5. It is electronegative in nature.
6. Its ionisation energy is high like halogens.
7. It is liberated at anode when NaH is electrolysed.
8. It shows –1 oxidation state when bonded to metal.
9. It forms many covalent compounds like halogens.
On the basis of its marked resemblance with alkali metals and halogens, it is very difficult to place it either
with the elements of group-1 or those of group-17.