# Gas


By [Janjik](https://paragraph.com/@janjik) · 2024-01-17

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**Gas** is one of the four fundamental [states of matter](https://en.wikipedia.org/wiki/State_of_matter). The others are [solid](https://en.wikipedia.org/wiki/Solid), [liquid](https://en.wikipedia.org/wiki/Liquid), and [plasma](https://en.wikipedia.org/wiki/Plasma_\(physics\)).[\[1\]](https://en.wikipedia.org/wiki/Gas#cite_note-1)

A pure gas may be made up of individual [atoms](https://en.wikipedia.org/wiki/Atoms) (e.g. a [noble gas](https://en.wikipedia.org/wiki/Noble_gas) like [neon](https://en.wikipedia.org/wiki/Neon)), [elemental](https://en.wikipedia.org/wiki/Chemical_element) molecules made from one type of atom (e.g. [oxygen](https://en.wikipedia.org/wiki/Oxygen)), or [compound](https://en.wikipedia.org/wiki/Chemical_compound) molecules made from a variety of atoms (e.g. [carbon dioxide](https://en.wikipedia.org/wiki/Carbon_dioxide)). A gas [mixture](https://en.wikipedia.org/wiki/Mixture), such as [air](https://en.wikipedia.org/wiki/Air), contains a variety of pure gases. What distinguishes gases from liquids and solids is the vast separation of the individual gas [particles](https://en.wikipedia.org/wiki/Particle). This separation usually makes a colorless gas invisible to the human observer.

The gaseous state of matter occurs between the liquid and plasma states,[\[2\]](https://en.wikipedia.org/wiki/Gas#cite_note-2) the latter of which provides the upper-temperature boundary for gases. Bounding the lower end of the temperature scale lie degenerative quantum gases[\[3\]](https://en.wikipedia.org/wiki/Gas#cite_note-3) which are gaining increasing attention.[\[4\]](https://en.wikipedia.org/wiki/Gas#cite_note-4) High-density atomic gases super-cooled to very low temperatures are classified by their statistical behavior as either [Bose gases](https://en.wikipedia.org/wiki/Bose_gas) or [Fermi gases](https://en.wikipedia.org/wiki/Fermi_gas). For a comprehensive listing of these exotic states of matter, see [list of states of matter](https://en.wikipedia.org/wiki/List_of_states_of_matter).

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*Originally published on [Janjik](https://paragraph.com/@janjik/gas)*