is a chemical element with
symbol ’O’ and atomic number ’8’.
Oxygen is an important part of the
atmosphere, and is necessary to
sustain most terrestrial life as it is
used in respiration.
Discovered in 1774.
is a colorless, odorless
gas with the molecular
formula O2, in which the two
oxygen atoms are chemically
bonded to each other.
heavier than air
soluble in water
without smell or taste
the gas is colourless, odourless
liquid O2 and solid O2 have a light
Melting point : -218.8 °C
( turns from solid to liquid )
Freezing point: Below -218.8 °C
( turns from liquid to solid )
Boiling point: -182.962 ° C
( turns from liquid to gas )
Oxygen is very reactive and capable of
combining with most other elements.
It is essential for the respiration of all
plants and animals and for almost all
This gas is used in various industrial
It is used to make acids, sulfuric acid,
nitric acid and other compounds.
Approximately 2/3 of the mass of the
human body is oxygen.
Oxygen is a combination of two Greek
words: ’oxys’, meaning ‘acid’, and ’genes’,
The atmosphere of Mars contains about
0.15 percent oxygen.
Nearly half of the mass of Earth's crust is
made up of oxygen.
The oxygen cycle describes the
movement of oxygen within its
three main reservoirs:
1. the atmosphere
mark the beginning of the
oxygen cycle. Plants are able to
make ‘oxygen’ for us by the process
known as photosynthesis.
Animals form the other half of the
oxygen cycle. We breathe in oxygen
which we process call respiration.