Which element constitutes the majority of Earth's atmosphere?

Nitrogen constitutes the majority of Earth's atmosphere, making up about 78% of the total volume. Its presence is crucial as it plays a fundamental role in various biological and ecological processes. Nitrogen is a key component of amino acids, proteins, and nucleic acids, which are essential for all forms of life.

The abundance of nitrogen in the atmosphere also serves several important functions. It acts as a diluent for oxygen, preventing fires and making the atmosphere more stable. Though oxygen is vital for respiration and combustion, it only comprises about 21% of the atmosphere. Other gases like carbon dioxide, which is important for plant photosynthesis, and trace gases like helium, are present in much smaller amounts, further highlighting nitrogen's dominance in the atmospheric composition.