||This article is written like a manual or guidebook. (January
2010)| Gas is one of the four fundamental states of matter (the
others being solid, liquid, and plasma). A pure gas may be made
up of individual atoms (e.g. a noble gas or atomic gas like
neon), elemental molecules made from one type of atom (e.g.
oxygen), or compound molecules made from a variety of atoms
(e.g. carbon dioxide). A gas mixture would contain a variety of
pure gases much like the air. What distinguishes a gas from
liquids and solids is the vast separation of the individual gas
particles. This separation usually makes a colorless gas
invisible to the human observer. The interaction of gas
particles in the presence of electric and gravitational fields
are considered negligible as indicated by the constant velocity
vectors in the image. The gaseous state of matter is found
between the liquid and plasma states, the latter of which
provides the upper temperature boundary for gases. Bounding the
lower end of the temperature scale lie degen