I'd say the most important gasses in the Earth's atmosphere are oxygen and water vapour.
Ozone gas makes one important part of the atmosphere. It protects us from the deadly UV rays.
Nitrogen is the most common gas in the earth's atmosphere (air is the name of that gas mixture).
Oxygen, now about 20% of the atmosphere, was not part of the original atmosphere of hthe Earth. It was produced by plants, after life developed.
oxygenammonia and some types of gas based carbon.
Nitrogen makes up approx. 80% of the atmosphere.
He thought that the early Earth's atmosphere contained ammonia, NH3; hydrogen gas, H2; water vapor, H2o; and compounds made of hydrogen and carbon, such as, CH4.
hydrogen
The atmosphere of the Earth is a gas, not a liquid, and although it does contain oxygen, that is just one part of the atmosphere, which is mostly nitrogen.
Oxygen
The Gas Giants have a deep gas atmosphere and earth have a not so deep atmosphere
The Gas Giants have a deep gas atmosphere and earth have a not so deep atmosphere
Water vapour. Or steam which is the gas state of water. Evaporation of water from the surfaces of rivers, lakes and mainly the oceans, an important part of the water cycle on Earth.