In this video we are going to investigate the properties of oxygen. Oxygen has atomic number 8 and is
found in group sixteen of the periodic table. It has the chemical symbol O.
Oxygen is of course a gas.
It has no smell, colour or taste but without it we as humans would not be able to inhabit planet earth.
When cool to very low temperatures it will form a liquid and a solid which are both
pale blue. Oxygen makes up 21 percent of the Earth's atmosphere. It has taken many
millions of years to make up this composition. Today's atmosphere seems to
now have the perfect balance. You may want to check the history of the atmosphere for
more details about this. Oxygen is used by the human body in a process called
respiration. Take a deep breath in, hold it for a few seconds. The air that entered your
body has now been held in the lungs. Some of the oxygen you breathe in
has been taken into the bloodstream and transported parts of the body where it's
needed. Respiration is taking place in the cells of your body
Oxygen combines with glucose, building up carbon dioxide and water. I'm releasing
energy. This enables cells to function and our bodies to survive. As you breathe
out air now contains roughly 4% less oxygen than when you breathed in.
This has been replaced by another gas called carbon dioxide. The oxygen in the atmosphere also affects our
lives in other ways. It reacts chemically with a number of other materials. Oxygen
will combine with reactive metals to form metal oxides. This is called
corrosion. Most metal oxides are useful as they produce a hard protective layer.
Aluminium oxide for example forms a protective layer on the surface of
aluminium. This grey coating protects the body of the metal underneath from
further corrosion. Modern aeroplanes have used this characteristic of aluminium as a
choice of construction material. Iron (III) oxide is formed when iron reacts with water and
oxygen, and this is not useful. You all know iron (III) oxide more commonly as rust. It makes the metal
flaky and weak. The corrosion will eat into the metal, which flakes off as the oxide
is built up. There are ways of protecting iron from oxidation. Putting oil on your
bike for example. It will protect it from the rust and keep it strong. Oxygen can be produced in
the lab by the chemical decomposition of hydrogen peroxide. If the earth's atmosphere
consisted of 30 percent oxygen rather than 21 percent, forest fires would start with lightning and
would never go out. Life as we know it would be impossible.