Nitrogen and Its Compounds (At a Glance)

 Basic Facts About Nitrogen

i. Symbol: N

ii. Atomic Number: 7

iii. Group: 15 (Group V A)

iv. Period: 2

v. Electronic Configuration: 1s² 2s² 2p³

vi. Valency: 3 or 5

vii. Nature: Non-metal

 Occurrence

* Makes up about 78% of Earth’s atmosphere as nitrogen gas (N₂) (free element)

* Found in: Proteins

 (amino acids)

* Nucleic acids (DNA & RNA)

* Fertilizers (nitrates, ammonium salts)

 Properties of Nitrogen Gas (N₂)

i. Colorless, odorless, tasteless gas

ii. Chemically inert due to strong triple bond (N≡N)

iii. Does not support combustion

iv. Slightly soluble in water

 Important Compounds of Nitrogen

1. Ammonia (NH₃)

               Prepared by: Haber Process
            

                 N2(g) + 3H2(g) → NH3(g)

      Properties Ammonia 

      i. Pungent smell

      ii. Highly soluble in water

       iii. Basic in nature

        Uses:

i.  used for Fertilizer production

ii.  As a Refrigerant

iii. For the Manufacture of nitric acid

2. Trioxonitrate V acid  (Nitric Acid) (HNO₃)

Prepared by: Ostwald Process

Properties:

i. Strong acid

ii. Oxidizing agent

Uses:

i. For manufacture of Fertilizers (ammonium nitrate)

ii. For making Explosives

iii. For Dye and drug manufacture

3. Nitrogen IV Oxide (NO₂)

i. It is a Reddish-Brown gas with choking smell

ii. It is Toxic and contributes to air pollution (one of the gases responsible for acid rain)

iii. Forms acid rain when dissolved in water

4. Dinitrogen I Oxide (Nitrous Oxide) (N₂O)

i. Commonly Known as laughing gas

ii. It is Used as anesthetic in medicine

5. Ammonium Salts (NH₄⁺ compounds)

Examples: NH₄Cl, (NH₄)₂SO₄

Uses:

i. Used as Fertilizers

ii. Used as Electrolytes in dry cells

 Nitrogen Cycle (Summary)

Nitrogen is recycled in nature through: 

Nitrogen Fixation (by bacteria or lightning)

Nitrification

Assimilation by plants

Ammonification
Denitrification

 Environmental Effects

Excess nitrogen compounds can cause: 

i. Eutrophication (water pollution)

ii. Acid rain

iii. Global warming (N₂O as greenhouse gas)

 Quick Summary

Nitrogen is essential for life but relatively inactive as N₂ gas
Its compounds (NH₃, HNO₃, nitrates) are highly reactive and useful and 
Plays a key role in agriculture and industry

Objective Questions

1. The percentage of nitrogen in the atmosphere is about
   A. 21%
   B. 50%
   C. 78%
   D. 90%

2. Nitrogen belongs to which group in the periodic table?
   A. Group 1
   B. Group 15
   C. Group 7
   D. Group 18

3. The bond between the two nitrogen atoms in N₂ is
   A. Single bond
   B. Double bond
   C. Triple bond
   D. Ionic bond

4. Nitrogen gas is relatively inert because
   A. It has low density
   B. It forms ions easily
   C. It has a strong triple bond
   D. It is a metal

5. The industrial method for producing ammonia is the
   A. Contact process
   B. Haber process
   C. Ostwald process
   D. Frasch process

6. The catalyst used in the Haber process is
   A. Platinum
   B. Iron
   C. Copper
   D. Zinc

7. Which of the following is a basic gas?
   A. CO₂
   B. NH₃
   C. SO₂
   D. NO₂

8. Ammonia is highly soluble in water because it
   A. Is non-polar
   B. Forms hydrogen bonds
   C. Is acidic
   D. Is heavy

9. The process used to manufacture nitric acid from ammonia is
   A. Haber process
   B. Contact process
   C. Ostwald process
   D. Cracking

10. Nitric acid is best described as
    A. Weak base
    B. Strong acid
    C. Neutral compound
    D. Salt

11. Which oxide of nitrogen is known as laughing gas?
    A. NO
    B. NO₂
    C. N₂O
    D. N₂O₅

12. The brown gas observed in air pollution is
    A. NO
    B. N₂O
    C. NO₂
    D. NH₃

13. Which of the following contributes to acid rain?
    A. NH₃
    B. NO₂
    C. N₂
    D. CH₄

14. Ammonium salts contain the ion
    A. NH₂⁻
    B. NH₄⁺
    C. NO₃⁻
    D. NO₂⁻

15. Which of the following is NOT a stage in the nitrogen cycle?
    A. Nitrification
    B. Assimilation
    C. Distillation
    D. Denitrification

16. Nitrogen fixation is the conversion of nitrogen into
    A. Oxygen
    B. Ammonia
    C. Carbon dioxide
    D. Hydrogen

17. Which of the following is used as a fertilizer?
    A. NH₄NO₃
    B. NaCl
    C. CO₂
    D. H₂O

18. Nitrogen does not support combustion because it
    A. Is reactive
    B. Is inert
    C. Is acidic
    D. Is alkaline

19. The oxidation state of nitrogen in NH₃ is
    A. -3
    B. +3
    C. +5
    D. 0

20. The main use of nitric acid is in the manufacture of
    A. Plastics
    B. Fertilizers
    C. Glass
    D. Cement