Question

Which three gases constitute most of the Earth's atmosphere?

Short answer

Nitrogen, oxygen, and argon are the three main gases in Earth's atmosphere.

Step-by-step solution

Identifying Atmospheric Gases

The Earth's atmosphere is composed of several gases, but not all are found in large quantities. The three gases that constitute the majority are nitrogen, oxygen, and argon.

Determining Proportions

Among the atmospheric gases, nitrogen makes up the largest portion at about 78% of the atmosphere. Oxygen comes next, comprising around 21% of the atmosphere, while argon, despite being the third most common gas, makes up just about 0.93%.

Conclusion

Based on the proportions, we can conclude that nitrogen, oxygen, and argon are the three most abundant gases, making up most of the Earth's atmosphere in that order.

Key concepts

Nitrogen

Nitrogen is the most abundant gas in the Earth's atmosphere. It makes up approximately 78% of the air we breathe. Nitrogen is a colorless and odorless gas, which is chemically stable under normal atmospheric conditions.
This stability is why it doesn't typically react with other elements or compounds in the atmosphere.
Nitrogen is essential for life. Plants need nitrogen for growth, but they cannot use nitrogen directly from the air. Instead, it must first be converted into a form plants can uptake through a process called nitrogen fixation.
This conversion is achieved naturally by certain bacteria and industrially through human-made processes. The nitrogen cycle is the pathway this element takes through the atmosphere, living organisms, and the Earth.

• Nitrogen is inert and generally non-reactive, making it vital in preventing inflammability in the atmosphere.
• Its abundance provides a buffer to the more reactive oxygen.
• Nitrogen compounds are crucial in various industrial applications, including agriculture and medicine.

Oxygen

Oxygen is the second most common gas in our atmosphere and comprises about 21% of the air. It is highly reactive and essential for the survival of most living organisms. Oxygen supports combustion and is critical for the respiration process, where it aids in converting food into energy.
The presence of oxygen enables life to thrive on Earth. Plants play an integral role in maintaining oxygen levels through photosynthesis. During this process, they convert carbon dioxide and water into glucose and oxygen, releasing oxygen back into the atmosphere.

• Oxygen plays a key role in biological processes such as respiration and metabolism.
• Industrial uses of oxygen include welding, metal cutting, and as a life-support component.
• The presence of oxygen in the atmosphere is also important for the formation of the ozone layer, which shields the Earth from harmful ultraviolet radiation.

Argon

Though argon constitutes only about 0.93% of the Earth's atmosphere, it is still the third most abundant gas within it. Argon is a noble gas, which means it is chemically inert under most conditions and does not easily form compounds with other elements.
This inertness is due to its full valence electron shell, which makes it stable and non-reactive. Argon's primary use is in providing an inert atmosphere in industrial processes such as arc welding and the production of lighting components.

• Argon is heavier than air, which allows it to create an effective barrier when needed.
• It is commonly used in energy-efficient homes to insulate windows, trapping heat inside during colder months.
• Argon is also utilized in advanced scientific research, including experiments that require non-reactive environments.