Chemistry - Oxygen


  • Oxygen is the member of group 16 on the periodic table; however, most of the time, it is treated differently from its group.

  • 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.

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.