Definition of Solid

What is a Solid?

Solids are one of the four common states of matter - the others are liquids, gases, and plasmas. In general, but not in all specific cases, as the temperature increases and pressure decreases substances pass through the four different states.

solid → liquid → gas → plasma

The Solid State

The solid state of matter is characterized by the following properties:

  • its volume is fixed; it will not expand to fill a container - unlike gases and plasmas
  • most solids are incompressible - their volume hardly changes when pressure changes - unlike gases and plasmas
  • solids are not fluids, so they cannot flow. Their shapes do not adapt to that of their containers - unlike liquids, gases, and plasmas
  • solids are condensed matter, so their volumes are similar to those of liquids, and much smaller than gases and plasmas

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