Hydrogen Class 11 Notes - Chapter 9

According to the CBSE Syllabus 2023-24, this chapter has been removed from NCERT Class 11 Chemistry textbook.

The lightest atom on earth is hydrogen which has a single electron. In the year 1766, Henry Cavendish was the first to discover it. The three stable isotopes of hydrogen are protium, deuterium, and tritium. The radioactive isotope among these three is tritium. Hydrogen is one of the most abundant elements found in the universe. Even though it resembles halogen and alkali metals, it has unique properties and has a separate position in the periodic table.

Water-Gas Shift Reaction

On an industrial scale level, Dihydrogen is prepared from petrochemicals by water-gas shift reaction. It is got in the form of a byproduct of the electrolysis of brine.

Also Read: Preparation Of Hydrogen And Uses

Bond Dissociation Enthalpy

Dihydrogen has the highest H-H bond dissociation enthalpy for a single bond between the two atoms. The H-H bond dissociation enthalpy equals 435.88 kJ mol–1

Read More: Bond Dissociation Enthalpy


Due to high negative dissociation enthalpy, dihydrogen is inactive at room temperature.  At suitable conditions, dihydrogen can combine with all the possible elements to form hydrides.

There are three different ways to categorize the hydride:

  • Saline or Ionic hydrides – Good reagent to prepare additional hydride compounds
  • Molecular or Covalent hydrides – Important for daily life. Example H2O
  • Non-stoichiometric or metallic hydrides – Used for ultra-purification of dihydrogen

Read More: Hydrides



Also Access 
NCERT Solutions for Class 11 Chemistry Chapter 9
NCERT Exemplar for Class 11 Chemistry Chapter 9

Important Questions

  1. How can you increase the production of dihydrogen from coal gasification?
  2. Explain the auto-protolysis of water along with its significance.
  3. Explain the amphoteric nature of water with chemical reactions.
  4. Distinguish between hydration and hydrolysis.

Explore more about this chapter and download Hydrogen Class 11 Notes PDF register with BYJU’S.

Other Important Links:

Frequently Asked Questions on CBSE Class 11 Chemistry Notes Chapter 9 Hydrogen


What is the hydrogen spectrum?

The hydrogen spectrum is an important piece of evidence to show the quantized electronic structure of an atom.


What are the uses of Hydrogen?

Hydrogen is used for fertilisers, grinding metals, and methanol to make ammonia for the manufacture of artificial materials such as plastics.


What are the main isotopes of hydrogen?

There are three isotopes of the element hydrogen: hydrogen, deuterium and tritium.


Leave a Comment

Your Mobile number and Email id will not be published.



Tuition Center
Tuition Centre
free trial
Free Trial Class
Scholarship Test
Scholarship Test
Question and Answer
Question & Answer