The Composition of Air
Air is a mixture of gases that makes up Earth's atmosphere. The most abundant gases in dry air are nitrogen (78%) and oxygen (21%). The remaining 1% consists of trace gases such as argon, carbon dioxide, and other gases.
Properties of Air
Air has several important properties, including:
- Weight: Despite being invisible, air has weight. The weight of the air above us is what creates atmospheric pressure.
- Expansion and Contraction: Air expands when heated and contracts when cooled. This property is the basis for many natural phenomena, such as winds and the movement of air masses in the atmosphere.
- Ability to Support Combustion: Oxygen in the air is essential for combustion. It is the reason why fires require oxygen to burn.
- Ability to Dissolve Gases: Air has the ability to dissolve gases, which is crucial for processes like respiration in living organisms.
Importance of Air
Air is essential for life on Earth. It plays a crucial role in several processes, including:
- Respiration: Animals and humans breathe in oxygen from the air for respiration.
- Photosynthesis: Plants use carbon dioxide from the air to produce oxygen through the process of photosynthesis.
- Weather and Climate: Air is responsible for the creation of weather patterns, including wind, clouds, and precipitation. It also plays a key role in regulating Earth's climate.
- Protection from Solar Radiation: The layer of air in the atmosphere acts as a shield, protecting the Earth from harmful solar radiation.
Study Guide
Here are some key points to remember about air:
- What are the two most abundant gases in dry air?
- What is the weight of the air above us responsible for?
- How does air behave when heated and cooled?
- Why is oxygen in the air important for combustion?
- What are some of the important roles of air in supporting life on Earth?
Understanding the composition and properties of air is essential for comprehending various natural phenomena and the interconnectedness of Earth's systems.
[Air] Related Worksheets and Study Guides:
.◂Science Worksheets and Study Guides Third Grade. Relationships among living things
Study Guide
Relationships among living things 
Activity Lesson
Relationships Among Living Things Worksheet/Answer key
Relationships among living things Worksheet/Answer key
Relationships among living things Worksheet/Answer key
Relationships among living things Worksheet/Answer key
Relationships among living things Vocabulary/Answer key
Relationships among living things Vocabulary/Answer key
Relationships among living things
Activity LessonWorksheet/Answer keyWorksheet/Answer keyWorksheet/Answer keyWorksheet/Answer keyVocabulary/Answer keyVocabulary/Answer keyThe resources above cover the following skills:
LIFE SCIENCE
From Molecules to Organisms: Structures and Processes
Create representations to explain the unique and diverse life cycles of organisms other than humans (e.g., flowering plants, frogs, butterflies), including commonalities such as birth, growth, reproduction, and death.
Unity and Diversity
Construct an argument from evidence to explain the likelihood of an organism’s ability to survive when compared to the resources in a certain habitat (e.g., freshwater organisms survive well, less well, or not at all in saltwater; desert organisms survive well, less well, or not at all in woodlands).
Create models that illustrate how organisms and their habitats make up a system in which the parts depend on each other.