Nitrogen-Occurrence, Preparation, and Properties

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Nitrogen fixation

Nitrogen fixation is a process in which nitrogen in the atmosphere is converted into ammonia. Nitrogen fixation, natural and synthetic, is essential for all forms of life because nitrogen is required to biosynthesize basic building blocks of plants, animals and other life forms, e.g., nucleotides for DNA and RNA and amino acids for proteins.

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Occurence of nitrogen family

Nitrogen makes about 78% by volume of the atmosphere. Phosphorous do not occur in free state and is very reactive. The elements arsenic, antimony and bismuth are not very abundant.

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Uses of nitrogen

Nitrogen is used to make fertilisers, nitric acid, nylon, dyes and explosives. Nitrogen gas is also used to provide an unreactive atmosphere. It is used in this way to preserve foods, and in the electronics industry during the production of transistors and diodes. 

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Methods of preparation of nitrogen

  • It is prepared from liquefaction of air and fractional distillation.
  • By thermal decomposition of ammonium nitrite: 
  • From ammonium dichromate:

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Properties of dinitrogen

  • It has two stable isotopes: and 
  • It is adsorbed by charcoal.
  • It is neutral to litmus.
  • It is neither combustible nor a supporter of combustion.

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Physical properties of dinitrogen

  • It is colourless, tasteless and non-toxic gas.
  • It is very slightly soluble in water.
  • It has low freezing point.

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Chemical properties of dinitrogen

  • It is inert and unreactive at room temperature.
  • It is neutral to litmus.
  • It combines with non-metals.
                
                
                

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Chemical properties of nitrogen family

The top two elements, nitrogen and phosphorus, are non-metals, forming -3 charged anions. Nitrogen is a diatomic gas and phosphorus is a solid. The elements arsenic, antimony, and bismuth all have some characteristics of semi-metals such as brittleness as a free element. They have 5 electrons in their valence shell.