Objectives of the sequence:

  • to know the composition of air
  • be able to carry out simple experiments in class to show some properties of air

Part 1: The materiality and the mass of air

Materiality of air

Experiment 1

Experiment 2

Mass of air

To remember

Air is a homogeneous mixture of different gases. The largest part in its formation is nitrogen gas (78%) and oxygen gas (21%), which make up 99% of air. One percent (1%) of the rest of the air consists primarily of carbon dioxide, argon, and water vapor, and certain other gases such as methane, helium, neon, krypton, nitrogen oxides as well as dust particles

Air is invisible and odorless but it has materiality, as well as mass and weight.

Part 2: The importance and the pressure of air

The importance of air

The pressure of air

Experiment 1

Experiment 2

To remember

The importance of air

Air is a vital substance essential to living beings.

Fuel combustion is not possible without the presence of air.

The sun’s harmful rays are filtered by the ozone layer in the air.

The air pressure

Atmospheric pressure is the force exerted by air particles above the surface of the earth and other objects.

The higher one moves away from the surface of the earth (by rising in altitude), the more the atmospheric pressure decreases.

Part 3: The air expansion and contraction, and the air pollution

The air expansion and contraction

Experience 1

Experience 2

The air pollution

To remember

The air expansion and contraction

When the temperature increases, the distance between the air particles increases and the air expands.

When the temperature decreases, the particles that make up the air retract and the air contracts.

Cold air has a higher pressure than warm air, and air moves from a cold environment to a warm environment.

The air pollution

The air is often polluted, mainly due to human activities but also due to natural phenomena such as volcanoes. It means that it contains particles other than the main components that compose air naturally.

This pollution is harmful to human health and the health of other living beings as well as to the environment around them.