Nitrogen
4 Minutes
Nitrogen gas facts for students, exploring its abundance, physical states, cooling uses, and chemical reactions. A short science lesson in English.
- Why nitrogen fills the atmosphere and its discovery by Carl Scheele
- Freezing an orange with liquid nitrogen and smashing it
- Reactions forming calcium nitride, ammonia, and stopping a flame
What this lesson teaches
Nitrogen is a chemical element that makes up most of the atmosphere on Earth because it is largely unreactive compared to other atmospheric gases. Discovered in 1772 by the Swedish chemist Carl Wilhelm Scheele, it is the seventh most abundant element in the universe.
Where nitrogen is found and used
- Nitrogen makes up most of Earth's atmosphere, and it also forms about 98% of the atmosphere of Titan, Saturn's natural satellite.
- It makes up about 3% of human body weight because it is an essential component of the proteins that build our bodies.
- While other atmospheric gases reacted with elements on Earth to form compounds like silicon dioxide, calcium carbonate, methane, and water, nitrogen remained mostly uncombined.
- In everyday life, nitrogen gas is used to fill vehicle tires and to preserve food inside snack packets.
Physical properties and states
Nitrogen is naturally a gas that has no color, no smell, and no taste, with a density lower than the surrounding air. When chilled below -196 degrees Celsius, it turns into a liquid that is cold enough to be used for refrigerator cooling. If liquid nitrogen is poured over a fresh orange, the fruit freezes completely solid and shatters like powder when hit with a hammer, instead of squashing. Cooling nitrogen further below -210 degrees Celsius solidifies it into a white solid.
Chemical reactions and combustion
Nitrogen rarely reacts with other substances, but it forms chemical compounds under increased temperature and pressure. When it combines with metals, it creates metal nitrides, such as calcium nitride formed from three calcium atoms and two nitrogen atoms. It can also combine with non-metals, such as reacting six hydrogen atoms with two nitrogen atoms to yield two molecules of ammonia. Nitrogen also does not support combustion, so directing nitrogen gas onto a burning candle will put the flame out.