solid, liquid and gaseous



We explain what a solid, a liquid and a gas is, the specific characteristics of each one and how it passes from one state to another.

All matter spontaneously occurs in one of the three main physical states.

What is a solid, a liquid, and a gas?

All matter that exists in the universe known is presented in a physical state determined, depending on its internal conditions of Energy (which determines the degree of cohesion of its particles) and the conditions of temperature and of Pressure of the environment that surrounds it.

These different physical states are scientifically known as states of matter aggregation and three main states are recognized: the solid state, the liquid and the gaseous, that is, solids, liquids and gases. There are other known states, such as plasma or Bose-Einstein condensate, but they are very rare in our daily lives, and some exist only in the laboratory.

Around us, all matter spontaneously presents one of these three main physical states (solid, liquid or gaseous) but, through the alteration of its physical properties such as temperature and pressure, it is possible to take it from one state to another, always through the addition or subtraction of energy to their particles. This procedure is known as the process of change phase or change of state of aggregation.

On the other hand, each state of matter has its own characteristics and physical properties, depending on the nature of the matter. substance that composes the subject under study. However, we must never confuse the physical state of matter with its chemical composition: the Water (H2O) will retain its chemical formula even if it is in liquid, solid or gaseous form (steam).

The changes between one phase and another do not alter the atomic composition of the substance at all (therefore, they are not chemical reactions), but they do serve to separate mixes, for example, using the difference in physical properties between its components.

The solids

Solids actively oppose change in shape and volume.

Solids are easily recognizable because they actively oppose change in shape and shape. volume, given that its particles are very close together and very ordered, and they present an enormous cohesion that allows them very little mobility. Therefore, we cannot easily deform most solids. Solids always tend to retain their well-defined and invariable structure.

Some characteristics of solids:

  • They have a specific shape, with well-defined boundaries, and they tend to preserve it.
  • They have a high density and a volume of its own.
  • They can float or submerge when thrown into a liquid.
  • They are more or less flexible or rigid, that is, they admit (or not) a certain margin of deformation before breaking.
  • Are ductile, malleable or brittle, depending on whether they can be molded into wires, plates or if they tend to break under continuous force.
  • They are incompressible, resistant to fragmentation and do not flow.

Solids arise as a consequence of processes of solidification o freezing of liquids, or deposition (or reverse sublimation) of gases. In addition, they can be melted into liquids or sublimate in gases through the injection of energy and suitable pressure conditions.


Liquids move on inclined surfaces.

Liquids can be understood as an intermediate state between the rigidity of solids and the volatility of gases. Its main feature is the ability to flow and the fact of not having its own shape, but of acquiring the shape of the container that contains them. This is because their atoms They present a much lower cohesion than that of solids, without completely losing the union between them.

Its main characteristics are:

  • They are fluid, that is, they can move on an inclined surface.
  • They do not have a fixed shape or structure memory, but they do have their own and constant volume. Therefore, they are not very compressible.
  • They have surface tension (initial resistance to penetration) and capillarity.
  • They generally dilate before the heat and they contract in the cold (except water).
  • Present viscosity, that is, a certain degree of adhesion between its particles and resistance to movement.

Liquids arise as a consequence of the fusion or the melting of a solid, or the condensation wave liquefaction (extreme compression) of a gas. On the contrary, to take them to the solid state it is necessary to freeze or solidify them in some way, and to turn them into a gas it is enough to subject them to evaporation (or vaporization).

The gases

Gases present the most volatile and least specific state of matter.

Finally, gases present the most volatile state of matter, in which the particles are further apart and dispersed than in the other two states, and they move much faster. The attraction between them is so low that gases tend to expand to fill the spaces that contain them, and the space between their particles is such that they can be greatly compressed.

Its fundamental characteristics are:

  • They have very low density, which allows a lot of compression.
  • They have no shape or volume of their own.
  • The gravitational forces they practically do not affect its particles, which move with immense freedom.
  • Its density undergoes important changes with temperature and pressure.
  • They are able to flow, just like liquids.

Gases are the product of different processes of sublimation of solids, or of evaporation of liquids, and can be converted to the solid state by deposition, and to the liquid by condensation (or liquefaction).

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