Grade 6 → Air and its composition ↓
The role of water vapor and other gases in air and its composition
Air is a fascinating and essential part of our world. It's the invisible mixture of gases that surrounds us, giving us the oxygen we breathe and helping to sustain life on Earth. But air isn't just made up of oxygen. It's made up of a variety of different gases, each of which plays an important role in our environment.
What is air made of?
To understand what air is, we need to look at the gases it contains. Air is made up of several major gases, each of which contributes to the different functions air performs. Let's start by listing the main gases found in air:
- Nitrogen ( N2 ) – About 78% of the air is composed of nitrogen.
- Oxygen ( O2 ) - Oxygen in the air is about 21%.
- Argon (Ar) - This noble gas makes up about 0.93% of the air.
- Carbon dioxide ( CO2 ) - contains about 0.04% in the air.
- Water Vapor (H 2 O) - The amount of water vapor can vary, typically between 0% and 4%.
- Other gases - These include neon, helium, methane, krypton, and hydrogen, which together make up less than 1% of the air.
Nitrogen and its role
Nitrogen is the most abundant gas in our atmosphere. It is an inert gas, meaning it does not react easily with other substances. Although it does not participate in chemical reactions under normal conditions, nitrogen is vital to life on Earth. Plants and animals need nitrogen to make proteins, which are essential for cells and tissues.
Visual example - nitrogen molecule
This picture shows a nitrogen molecule with two nitrogen atoms bonded together, written as N 2
.
Oxygen: Essential for life
Oxygen is the second most abundant gas in the atmosphere and is essential for life. Humans and animals need oxygen to breathe. It plays a vital role in respiration, a process that releases energy from food.
Oxygen is also important for combustion, which is the process of burning. This is why fires need oxygen to keep burning.
Visual example - oxygen molecule
This is a simplified representation of the oxygen molecule, made up of two oxygen atoms bonded together, written as O 2
.
Argon: The noble gas
Argon is the third most common gas in the atmosphere. It is a noble gas, meaning it does not react easily with other elements. Argon is often used in light bulbs and welding to provide an inert atmosphere, preventing chemical reactions that could damage the material or the bulb.
Fun facts
Did you know? Although argon makes up only 0.93% of the air, it is more abundant than carbon dioxide!
Carbon dioxide: A greenhouse gas
Carbon dioxide is a small component of air but plays a vital role in climate regulation. Plants use carbon dioxide for photosynthesis, the process through which they make food using sunlight.
Carbon dioxide is considered a greenhouse gas because it contributes to the greenhouse effect by trapping heat in Earth's atmosphere. This effect keeps our planet warm enough to sustain life.
Visual example - carbon dioxide molecule
This picture shows a carbon dioxide molecule, composed of one carbon atom and two oxygen atoms, written as CO 2
.
Water vapor: Invisible water
Water vapor is water in the gaseous state. You can't see water vapor, but it's always present in the air to some degree. It plays an important role in weather and climate.
When the air is warm, it can hold more water vapor, making it feel moist. Humidity is the amount of water vapor in the air. When the air cools, it can't hold as much water vapor, causing condensation and the formation of clouds, dew, or rain.
Visual example - water cycle
This image shows the water cycle: the sun's heat causes ocean water to evaporate, turn into clouds, and eventually return to the ocean as precipitation.
Other gases
While other gases such as neon, helium, methane, krypton, and hydrogen make up less than 1% of the atmosphere, they still have important roles. For example, helium is used in balloons because it is lighter than air, and neon lights produce bright colors for signs.
Visual example - balloon filled with helium gas
This is a view of a balloon filled with helium. Helium (He) helps the balloon float because it is lighter than the surrounding air.
Conclusion
Air is a mixture of different gases, each of which plays a unique and irreplaceable role. From providing oxygen for living creatures to enabling rain, these gases interact in a delicate balance that supports life on Earth. Understanding how these gases interact and affect our daily lives is an essential part of learning about the natural world.
In short, air isn't just the invisible oxygen we breathe or the nitrogen that makes up the biggest part of it. It's a complex mixture that affects weather patterns, climate change, and even the sound of a helium-filled balloon at a party.