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The p-Block Elements

Group 15 elements:

  • The valence shell electronic configuration is ns2 np3.
  • Nitrogen differs in chemical properties from other elements of the group due to its small size, high electronegativity, high ionisation enthalpy and non-availability of d-orbitals.
  • They exhibit two oxidation states, +3 and +5. Heavier elements exhibit mainly +3 oxidation state due to inert pair effect.

The main use of nitrogen is in the manufacture of ammonia


  • On a small scale, ammonia is obtained from ammonium salts, which decompose when treated with caustic soda or lime. It forms metal salt, water, and ammonia gas.
  • Ammonia can also be prepared by treating metal nitrides with warm water.
  • It has trigonal pyramidal structure with nitrogen atom at the apex.


  • Forms
    • Dry ammonia gas (gaseous ammonia)
    • Liquid ammonia (liquified ammonia)
    • Liquor ammonia fortis (saturated solution of ammonia in water)
    • Laboratory bench reagent (dilute solution of liquor ammonia)
  • ​On large scale, ammonia is obtained by Haber’s process.
    • Raw material: Mixture of hydrogen and nitrogen gases in the ra…

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