How does the gasses in earths air differ from place to place

As molten rocks cool gases such as nitrogen water vapor and carbon dioxide are released

Gasses on and in the earth differ places to places because- 
1. depends on their weight and mass, looking at how many no. of protons, neutrons and electrons are there. 
ex. oxygen is less in mountainous area because they are heavier than other gases.
2. depends on the what extra things the atom needs to be stable, like 4 more electrons or any more.
3. depends on their radioactivity and electromagnetic waves
PS: dont write the last one not really sure abt that