What percentage of the atmosphere is nitrogen?

Approximately 78% of the Earth's atmosphere is composed of nitrogen.

Nitrogen is the most abundant gas in the Earth's atmosphere, making up about 78% of the total volume. This means that for every 100 molecules of gas in the atmosphere, 78 of them are nitrogen. The rest of the atmosphere is primarily composed of oxygen (about 21%), with small amounts of other gases such as argon, carbon dioxide, and trace gases.

Nitrogen is a colourless, odourless, and tasteless gas that is relatively inert, meaning it doesn't readily react with other elements. This makes it a stable component of the atmosphere. Nitrogen is essential for life on Earth, as it is a key component of amino acids, proteins, and DNA. However, most organisms cannot use atmospheric nitrogen directly and rely on certain bacteria to convert it into a usable form through a process called nitrogen fixation.

The high percentage of nitrogen in the atmosphere is a result of billions of years of volcanic activity, which released nitrogen and other gases from the Earth's interior. Over time, the lighter gases such as hydrogen and helium escaped into space, while heavier gases like nitrogen and oxygen remained, leading to the current composition of the atmosphere.

In summary, nitrogen is the most abundant gas in the Earth's atmosphere, making up approximately 78% of its total volume. It is a stable, inert gas that is essential for life on Earth.