states of the material

Chemistry

2022

We explain what they are and what are the states of aggregation of matter. Solid, liquid, gaseous and plasma states.

Matter in a solid state has its particles very close together.

What are the states of matter?

The states of matter are the different phases or aggregation states in which the matter known, be pure substances or mixtures. The state of aggregation of a substance depends on the type and intensity of the binding forces that exist between its substances. particles (atoms, molecules, ions, etc.). Other factors that influence the state of aggregation are temperature and pressure.

The best known states of matter are three: solid, liquid and gaseous, although there are also other less frequent states such as plasma and other forms that do not occur naturally in our environment, such as fermionic condensates. Each of these states has different physical characteristics (volume, fluency, endurance, among other).

Changes in the states of the matter

Modifying the conditions of temperature Y Pressure, the state of aggregation of a substance can be transformed but its chemical properties will remain the same. For example, we can boil Water to make it go from a liquid to a gaseous state, but the water steam The resulting product will still be made up of water molecules.

The transformation procedures of the phases of matter are usually reversible and the best known are the following:

  • Evaporation. It is the process by which, by introducing caloric energy (heat), part of the mass of a liquid (not necessarily the entire mass) is transformed into gas.
  • Boiling or vaporization. It is the process by which, supplying heat energy, the entire mass of a liquid is transformed into a gas. The phase transition occurs when the temperature rises above the boiling point (temperature at which the vapor pressure of the liquid equals the pressure surrounding the liquid, therefore it becomes vapor) of the liquid.
  • Condensation. It is the process by which, by removing heat energy, a gas is transformed into a liquid. This process is contrary to vaporization.
  • Liquefaction. It is the process by which, by greatly increasing the pressure, a gas is transformed into a liquid. In this process, the gas is also subjected to low temperatures, but what characterizes it is the high pressure to which the gas is subjected.
  • Solidification. It is the process by which, increasing the pressure, a liquid can transform into a solid.
  • Freezing. It is the process by which, by removing heat energy, a liquid turns into a solid. The phase transition occurs when the temperature takes values ​​lower than the freezing point of the liquid (temperature at which the liquid solidifies).
  • Fusion. It is the process by which, supplying heat energy (heat), a solid can be transformed into a liquid.
  • Sublimation. It is the process by which, supplying heat, a solid is transformed into a gas, without first passing through the liquid state.
  • Deposition or reverse sublimation. It is the process by which, withdrawing heat, a gas becomes a solid, without first passing through the liquid state.

Solid state

Solids have little or no fluidity and cannot be compressed.

Matter in solid state it has its particles very close together, held together by attractive forces of great magnitude. Because of this, solids have a definite shape, high cohesion, high density and great resistance to fragmentation.

At the same time, the solids have low or no fluidity, they cannot be compressed, and when they are broken or fragmented, other smaller solids are obtained from them.

There are two types of solids, according to their shape:

  • Crystalline. Its particles are arranged in cells in a geometric shape, so they are usually regular in shape.
  • Amorphous or vitreous. Its particles do not gather into one structure neat, so its shape can be irregular and varied.

Examples of solids are: minerals, metals, the stone, the bones, timber.

The liquid state

The particles of liquids are still held together by attractive forces, but much weaker and less ordered than in the case of solids. Therefore, liquids do not have a fixed and stable shape, nor do they present high cohesion and endurance. In fact, liquids take the shape of the container that contains them, they have great fluidity (they can enter through small spaces) and a surface tension that makes them adhere to objects.

Liquids are not very compressible and, with the exception of water, they tend to contract in the presence of cold.

Examples of liquids are: water, mercury (despite being a metal), blood.

The gaseous state

In many cases the gases are colorless and / or odorless.

In the case of gases, the particles are in such a state of dispersion and distance that they hardly manage to stay together. The force of attraction between them is so weak that they are in a disordered state, which responds very little to gravity and occupy a much larger volume than liquids and solids, so a gas will tend to expand until occupying the entire space in which it is contained.

Gases do not have a fixed shape or volume fixed and on many occasions they are colorless and / or odorless. Compared to other states of aggregation of matter, they are not chemically reactive.

Examples of gases are: air, the carbon dioxide, nitrogen, helium.

Plasma state

Plasma is an excellent transmitter of electricity and magnetism.

A state of aggregation of the particular matter is called plasma, which can be understood as an ionized gas, that is, composed of atoms to which they have been removed or added electrons and therefore have a fixed electrical charge (anions (-) and cations (+). This makes plasma an excellent transmitter of the electricity.

On the other hand, plasma particles interact very strongly with electromagnetic fields. Because plasma has its own characteristics (which do not correspond to solids, gases, or liquids) it is said to be the fourth state of matter.

There are two types of plasmas:

  • Cold plasma. It is the plasma in which the temperature of the electrons is higher than that of the heavier particles, such as ions.
  • Hot plasma. It is the plasma whose ionized atoms become enormously hot because they are continuously colliding and this generates light And heat.

Examples of plasma are: Sun, electronic screens, or inside fluorescent tubes.

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