What are the states of matter? Concept, Changes and Examples

What are the states of matter?

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

What are the states of matter

Solid matter has its particles very close together.

The states of matter are the different phases or states of aggregation in which known matter can be found, whether pure substances or mixtures, depending on the type and intensity of the bonding forces that exist between their particles (atoms, molecules, ions, etc.).

The states of matter commonly known are three: solid, liquid and gaseous, although there are also other less frequent such as plasma and other forms that do not occur in our environment naturally, such as fermionic condensates.

Each of these states has different physical characteristics, such as volume, fluidity, resistance, etc.

State of matter changes

Similarly, matter can be transformed from one state to another, altering the conditions of temperature and pressure at which it is found; but the chemical properties of its components will remain the same.

For example, we can boil water to make it go from a liquid to a gaseous state, but the resulting steam will still be composed of hydrogen and oxygen molecules.

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

  • Steaming or evaporation. By introducing caloric energy (heat), a liquid is converted into a gas.
  • Condensation. Removing caloric (cold) energy turns a gas into a liquid.
  • Liquefaction. By subjecting a gas to very high pressures, it becomes a liquid without changing the temperature at which it is found.
  • Solidification. By withdrawing caloric (cold) energy, a liquid can be converted into a solid.
  • Fusion. By adding heat energy (heat), a solid can be melted into liquid.
  • Sublimation. Certain solids, upon receiving caloric energy, are converted into gas without first passing through the liquid state.
  • Deposition. Certain gases, when losing caloric energy, become solids without first passing through the liquid state.

The solid state

Solids have low or no fluidity and cannot be compressed.

Matter in solid state has its particles very close together, joined by forces of attraction of great magnitude.

That is why they behave like a single body, endowed with great cohesion, constant density and form, resistance to fragmentation and form memory, that is, they tend to remain equal to themselves.

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

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

  • Crystalline. Their particles are arranged in geometrically shaped cells, so they usually have a regular shape.
  • Amorphous or vitreous. Its particles do not come together in an ordered structure, so its shape can be irregular and varied.

Examples of solids are: minerals, metals, stone, bones, wood.

The liquid state

The particles of liquids are still united by attraction forces, but much weaker and less orderly than in the case of solids. Therefore, liquids do not have a fixed and stable form, nor do they present so much cohesion and resistance.

In fact, liquids take on the shape of the container containing them, they have great fluidity (they can be introduced through small spaces) and a surface tension that makes them adhere to objects.

Liquids are uncompressible and, with the exception of water, tend to contract in the presence of cold.

Examples of liquids are: water, mercury, blood.

The gaseous state

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

In the case of gases, the particles are in such a state of dispersion and remoteness that they barely manage to stay together at all.

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 that a gas will tend to expand to occupy the entire space in which it is contained.

The gases do not have a fixed shape or fixed volume, and in many cases they are colourless and/or odourless. In comparison with other phases of matter they are chemically little reactive.

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

The Plasma State

Plasma is a particular state of aggregation, which can be understood as an ionized gas, i.e. composed of atoms from which electrons have been removed and thus have a fixed electrical charge (anions + and cations -). This makes the plasma an excellent transmitter of electricity and magnetism.

There are two types of plasmas:

  • Cold plasma. They are operated at room temperature because only electrons are charged with energy.
  • Hot plasma. Ionized atoms heat up enormously, generating light and heat.

Examples of plasma are the sun, electronic screens, or the inside of fluorescent tubes.

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