Matter consists of atoms held together by
electromagnetic forces. How tight these bonds are determines which
of the four states: solid, liquid, gas or plasma, matter exists as.
Plasmas are only found naturally in the coronae and cores of stars.
They can also be created experimentally in laboratories such as
JET.
As the atoms move faster, the distances between
them increases. Heating increases the motion of atoms and causes
the matter to go from solid (ice) to liquid (water) to gas
(vapor).
Heat and temperature is explained in atomic
theory as the motion of the atoms (faster = hotter).
Pressure is explained as the momentum transfer of
those moving atoms on the walls of the container (faster atoms =
higher temperature = more momentum/hits = higher pressure).
In the physical sciences, a phase is a set of
states of a macroscopic physical system that have relatively
uniform chemical composition and physical properties (i.e. density,
crystal structure, index of refraction, and so forth). The most
familiar examples of phases are solids, liquids, and gases. Less
familiar phases include: plasmas and quark-gluon plasmas;
Bose-Einstein condensates and fermionic condensates; strange
matter; liquid crystals; superfluids and supersolids; and the
paramagnetic and ferromagnetic phases of magnetic materials.
Phases are sometimes called states of matter, but
this term can lead to confusion with thermodynamic states. For
example, two gases maintained at different pressures are in
different thermodynamic states, but the same "state of
matter".
1. Matter
