11th Chemistry NCERT notes

Hydro = water, gennas = producer

Position of Hydrogen in periodic table

  • Electronic Configuration of Hydrogen 1s1
  • The position of hydrogen in the periodic table is not justified because it resembles both alkali metals (group I) as well as halogens (group 17).

Occurrence of Hydrogen

Hydrogen is the most abundant element in the universe. It is present in combined state as water, coal, animal and vegetable matter. All organic compounds contain hydrogen as an essential constituent.

Isotopes of Hydrogen

Hydrogen has three isotopes.

  • Protium, 1H1
  • Deuterium, 1H2
  • Tritium, 1H3
Isotopes of Hydrogen
Isotopes of Hydrogen
Atomic No. Mass No.
Protium 1 1
Deuterium 1 2
Tritium 1 3



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