1.
The layer of gases surrounding Earth.
2.
Made smaller by pressing together; gases can be compressed because there is space between particles.
3.
Not able to be seen, as with many gases.
4.
A level or stratum of material or substance, like layers in the atmosphere.
5.
To make the environment dirty or harmful by adding waste or toxic substances.
6.
The presence of harmful or toxic substances in the environment.
7.
Characteristics used to describe a substance, like color, smell, or ability to flow.
8.
The arrangement or organization of particles in a substance.
