Final answer:
The atmosphere at sea level mainly consists of nitrogen (78%), oxygen (21%), and argon (1%). These make up 99% of the atmosphere, with other trace gases contributing to the remaining 1%. The atmospheric pressure is a sum of the partial pressures of these gases.
Step-by-step explanation:
The composition of atmospheric air at sea level is primarily made up of three main gases: nitrogen, oxygen, and argon, with the formula being written as N₂ + O₂ + Ar. These gases collectively make up 99% of the atmosphere.
Nitrogen is the most abundant gas in the atmosphere, accounting for approximately 78% of the air we breathe. Oxygen comes next, making up around 21%, which is vital for the sustenance of life on Earth through the process of respiration.
Argon, a noble gas, is the third most abundant component of air at about 1%. Besides these major components, there are trace amounts of other gases such as carbon dioxide (CO₂), water vapor (H₂O), and various others that contribute to the remaining 1% of the atmospheric composition. Even though present in small quantities, these trace gases, especially carbon dioxide and water vapor, have significant effects on climate and weather patterns.
The pressure exerted by the atmosphere, known as atmospheric pressure, is the total of the partial pressures of these individual gases. At sea level, often measured as 1 atmosphere (atm) or 101.3 kPa, this pressure is significant to various scientific calculations and understanding of weather phenomena.