| A | B |
|---|
| Air | Is a gas that is found all around us |
| Nitrogen | 80% of air is made up of this gas |
| Oxygen | 20% of air is made up of this gas |
| Atmospheric Pressure | the force that is exerted by air |
| Atmosphere | a layer of gases 450 km deep where air is found |
| carbon dioxide | only trace amounts of this gas is found in air |
| air pressure | Pressure exerted by air |
| molecules/atoms | small units that make up all substances on earth |
| contracts | when something becomes smaller or tighter |
| expand | when something becomes larger |
