Atoms, Molecules and the Atmosphere

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Breathe in a lung full of air

There are billions of molecules being inhaled by you right now!

Air is made up mostly of nitrogen and oxygen, but your breath is a mixture of other gases as well.

Nitrogen - N2

• Two atoms of the element nitrogen combine to form a molecule of gas nitrogen

• Nitrogen is 80% of the atmosphere

In a car engine, nitrogen gas reacts with oxygen to produce nitrogen dioxide (NO2), a very toxic red-brown gas.

Argon (Ar)

Argon atoms do not combine with other atoms to form molecules.

Harmless argon gas is composed of single atoms of argon which leaks from inside the earth.

Oxygen (O2 and O3)

Atoms of the element oxygen can combine to form two different molecules.

Oxygen gas makes up 21% of the air we breathe. Almost all organisms need oxygen to survive.

The less common oxygen molecule, called ozone (O3), contains three atoms of oxygen. It is formed naturally in the upper layers of the atmosphere.

Chloroflurocarbons (CFCs)

CFCs have been destroying the ozone layer at an alarming rate. Because this layer is thinning, harmful ultraviolet light is reaching the Earth’s surface.

This ultraviolet light damages the skin.

CFCs are made up of carbon, chlorine and fluorine atoms.

CFCs are widely used as:

•solvents in cleaners•coolants in refrigeration and air conditioning

•blowing agents in the production of foam

•propellants in aerosols.

Carbon Dioxide (CO2) andCarbon Monoxide (CO)

Two atmospheric gases contain only atoms of carbon and oxygen.

Carbon dioxide is necessary for life on earth.

Carbon monoxide is extremely poisonous to vertebrate animals.

Gases in Earth’s Atmosphere

Air gets thinner as you get higher above earth. 90% of all molecules in the air are located in the troposphere.

30km

20km

10km

Sea Level

Task

• Referring to pages 60 and 61, complete questions 1, 2, and 3