Oxygen notes

Oxygen has atomic number 8 and the symbol O

An oxygen atom has 8 electrons, 8 protons and 8 neutrons

Oxygen is a member of the chalcogen group on the periodic table,
a highly reactive nonmetal, and an oxidizing agent.

Oxygen's melting point is -218.79 degrees celcius
And oxygen's boiling point is - 297.332 degrees celcius.

At standard temperature and pressure, two atoms of oxygen bind to
form dioxygen, a colorless and odorless diatomic gas with the formula O2.

Dioxygen (O2) is used in cellular respiration
and many major classes of organic molecules in living organisms contain oxygen,
like proteins, nucleic acids, carbohydrates, and fats,
And the major constituent inorganic compounds of animals.

Oxygen is continuously replenished by photosynthesis here on earth,
in which for example trees, grass and algea use the energy of sunlight
to produce oxygen as a byproduct carbon dioxide and water.

Another allotrope (form) of oxygen is ozone (O3).
It strongly absorbs ultraviolet radiation. And the high altitude ozone layer
protects life here on earth for example.

Uses:
 Residential heating.
 Life support systems which have normal air oxygen in it.
 Internal combustion engines.
 Production of steel.
 Production of plastics and textiles.
 Brazing.
 Welding and cutting of steels and other metal.
 And as a rocket propellant.