1. THE ATMOSPHERE
By Sean Noonan
By Sean Noonan

2. What is the atmosphere?
The atmosphere is the layer of gasses that blanket the Earth. The atmosphere is commonly known as air. Gravity holds the atmosphere close to the Earth surface.

3. Composition of the air
The air in our atmosphere is a mixture of gases including nitrogen, oxygen, carbon dioxide, argon, water vapour and other gases.
As air is a mixture, the percentages of the gases it is made up of can change.
For example ,humans and plants in a sealed room will change the composition of the air through respiration and photosynthesis .This is because these processes change the amounts of oxygen ,carbon dioxide and water in the air.

4. Oxygen Oxygen Uses Properties Test Respiration. Combustion.
Colourless, odourless, tasteless.
Only slightly soluble in water.
Supports combustion.
Reacts with many elements to form oxides.
Test
No effect on litmus.
Relights a glowing splint.
Uses
Respiration.
Combustion.
Medicine (ventilation and resuscitation)
Diving and mountain climbing gear.
Welding and cutting metals.
Steel manufacture.
Launching rockets.

5. Carbon dioxide Properties Test Uses Colourless ,odourless tasteless.
Only slightly soluble in water.
Slightly soluble in water.
Slightly more dense than air.
Does not support combustion.
Test
Changes limewater from colourless to milky.
Dissolves in water to from carbonic acid, which turns blue litmus red.
Uses
Photosynthesis.
Fire extinguishers.
Refrigeration and food packaging.
Carbonation (fizzy drinks)
Special effects (dry ice)