JSS 2: OXYGEN

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Oxygen is one of the most abundant and important elements on Earth. It is essential for respiration in humans, animals, and many other living organisms. Oxygen also supports combustion(burning).
Chemical Symbol of oxygen: O
Atomic Number of oxygen: 8
Mass number of oxygen: 16
Molecular Formula of oxygen: O₂
                 Isotopes of oxygen 
The isotopes of oxygen are:
1. Oxygen-16 (¹⁶₈O)
2. Oxygen-17 (¹⁷₈O)
3. Oxygen-18 (¹⁸₈O)

               Occurrence of Oxygen
Oxygen occurs:
1. In the atmosphere as oxygen gas (about 21% of air).
2. In water (H₂O).
3. In rocks and minerals as oxides.
4. In living plants and animals.

     Physical Properties of Oxygen
1. It is a colourless, odourless and tasteless gas
2. It is slightly soluble in water.
3. It is denser than air.
4. It exists as a diatomic molecule (O₂).

      Chemical Properties of Oxygen
1. It supports combustion but does not burn itself.
2. It reacts with metals to form metal oxides.
                  2Mg + O₂ → 2MgO
3. It reacts with non-metals to form non-metal oxides.
                   S + O₂ → SO₂
4. It is a strong oxidising agent.

       Laboratory Preparation of Oxygen
Oxygen is prepared in the laboratory by heating potassium chlorate(V) in the presence of manganese(IV) oxide (MnO₂) as a catalyst.
                2KClO₃ → 2KCl + 3O₂

                   Test for Oxygen
When a glowing splint is placed into a container of oxygen, it relights or rekindles. This is the test used to identify oxygen gas."

                   Uses of Oxygen
1. Oxygen is used for breathing in hospitals.
2. Used by scuba divers.
3. Used in welding and metal cutting.
4. Used in the manufacture of steel.
5. Used in rocket propulsion as liquid oxygen.
6. It supports combustion in industries.

             Importance of Oxygen
1. Oxygen is essential for respiration.
2. Supports burning.
3. It helps in energy production in living cells.
4. It helps to maintain aquatic life through dissolved oxygen in water.





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