Chemistry – Oxygen – Notes For W.B.C.S. Examination.

রসায়নের নোট – অক্সিজেন – WBCS পরীক্ষার  জন্য ।

• Oxygen is the member of group 16 on the periodic table; however, most of the time, it is treated differently from its group.Continue Reading Chemistry – Oxygen – Notes For W.B.C.S. Examination.
• The symbol of oxygen is ‘O’ and atomic number is ‘8.’
• Oxygen has about nine allotropes and the most common allotrope is diatomic oxygen (i.e. O₂). Other important allotrope is Ozone i.e. O₃.
• Oxygen, first time, was noticed by Swedish pharmacist Carl Wilhelm Scheele.

Salient Features of Oxygen

• Oxygen is characteristically categorized as the member of “chalcogen” group.
• The word “chalcogen” is derived from a Greek word “khalkόs,” which means “copper” and the Latin-Greek word “Genēs,” which means born or produced.
• Oxygen is a highly reactive gas (or nonmetallic element); hence, it is an oxidizing agent that readily forms oxides with most of the elements and compounds.
• Oxygen has six valence electrons.
• The melting point of oxygen is -218.8⁰C and the boiling point is -183⁰C.

Occurrence of Oxygen

• With about 20.8 percent share (in total earth’s atmospheric constituents), oxygen is the second ranked element of the earth’s atmosphere.
• Oxygen occurs almost in sphere of the earth namely atmosphere, hydrosphere, and lithosphere.
• During the photosynthesis process, free oxygen is produced by all green plants.
• Oxygen occurs as constituent copper ores.
• A human body contains about 65 percent oxygen.
• By mass, almost half of the earth’s crust is composed of oxygen (i.e. its oxides).
• By mass, oxygen is the third-most abundant element that found in the universe; the first and second are hydrogen and helium accordingly.
• Oxygen (i.e. O₂) is a colorless and odorless diatomic gas.
• Oxygen dissolves in water very easily; however, the solubility of oxygen in the water is temperature-dependent.

Compounds of Oxygen

• Following are the major compounds of oxygen −
  • Oxide
  • Peroxide
  • Carbon dioxide – CO₂
  • Hydroxide – OH^–
  • Ozone – O₃
  • Mercury (II) oxide – HgO
  • Chlorate – ClO₃
  • Aluminum oxide – Al₂O₃
  • Carbon monoxide – CO
  • Hypochlorite – ClO^–
  • Silicon dioxide – SiO₂
  • Hypofluorous acid – HOF
  • Sodium peroxide – Na₂O₂
  • Potassium chlorate – KClO₃
  • Oxygen difluoride – OF₂
  • Sodium oxide – Na₂O

Uses of Oxygen

• Oxygen (O₂) is the most essential requirements for the respiration, without it, life cannot be imagined.
• Oxygen is used in medicine.
• Oxygen therapy is typically used to treat some diseases, such as, emphysema, pneumonia, some heart disorders, etc.
• Some of the underwater activities, such as scuba diving, submarines, etc. also use artificial oxygen.
• Aircrafts, mountaineers, etc. also use artificial oxygen.
• Oxygen is also used in some of the industries, e.g. smelting of iron ore into steel – in this process, about 55% of oxygen is used.

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