We explain what states of aggregation are and how they are classified. We also explain their characteristics and the changes they undergo.
What are aggregation states?
They are called states of aggregation of matter (or simply states of matter) the phases or moments presented by the different known substances, according to the bonding forces existing between the particles that compose them. Traditionally, four phases of matter are known: liquid, solid, gas and plasma.
Each of these phases or moments, called “states”, has its own physical characteristicsdifferent from those presented by the same substance in other different states, even though its chemical constitution (the atomic composition of the particles that compose it) does not change at all.
It is understood, then, that all matter is in some kind of phase at a certain timebut it can be taken to another by varying the temperature and/or pressure to which it is subjected, thus giving rise to a series of physical processes called “phase change methods”: solidification, fusion, sublimation, deposition, condensation, vaporization , ionization and deionization.
See also: Metalloids
Types of states of matter
They know each other four types of states of matter: solid, liquid, gas and plasmaeach one different in variables such as hardness, resistance, malleability, fluidity, volume and cohesion, as well as in the relationship between its determined particles.
However, it is possible to bring matter to states of aggregation that do not ordinarily occur in nature but under very specific and controlled laboratory conditions: Bose-Einstein condensate, Fermi condensate, supersolid or quark-gluon plasma, the latter still hypothetical in nature.
Solid state
The solid state is recognizable because the matter has a defined body, with its own volume and constant shapedepending on the substance in question. Its atoms form tight, rigid structures, which offer resistance to external forces.
In general terms, are resistant to fragmentationhave little or no fluidity, high cohesion and a shape memory that gives them elasticity, that is, the ability to recover their shape if they are removed from their original configuration.
Examples of matter in a solid state are ice, stone, ceramic, wood, bone.
Continue in: Solid State
Liquid state
Matter in liquid state It has a much looser bond between its atoms as in the case of solids, which gives it fluidity, its main characteristic.
This means that matter does not have a specific shape but assumes that of the container in which it is contained.
In general terms, liquid matter has less cohesionmovement of kinetic energy, fluidity, diffusion, low compressibility and contraction in the presence of cold (except water).
Examples of matter in a liquid state are water, mercury, blood, milk.
Gaseous state
Matter in a gaseous state is called “gas” and It is composed, more than anything, of loosely united particlesexpanded and with a very slight force of attraction, which prevents them from having a defined shape and volume.
The release of a gas, in fact, causes it to expand freely until it fills the container in which it is contained.
The gases They have a very low densitysince its particles present a relative disorder: they move very quickly.
They also have a low response to the action of gravity, almost zero cohesion and variable volumebut a very high compression capacity.
Examples of gases are ozone, natural gas from kitchens, heliumand the gases that make up the atmosphere.
More in: Gaseous state
plasma state
When we talk about a plasma or a substance in a plasmatic state, we talk about an ionized gasthat is, whose atoms have lost their electroneutrality and form anions (-) or cations (+).
This means that the plasma state is similar to the gaseous state, but with properties quite different from those of “cold gas”such as its tendency to conduct electricity or its great response to magnetic fields.
There are two types of plasma:
- The cold plasma. It does not cause burns because its particles do not move as quickly as its electrons do.
- The hot plasma. In which the atoms are colliding with each other as they move (and losing electrons) and generate light and heat in the process.
An example of plasma matter is the fire, or even the sunor the content of plasma lamps.
Solid state changes
The solid state of aggregation can become liquid or gaseous, through processes known as:
- Fusion. Passage from solid to liquid. It generally requires an increase in temperature, which induces the particles almost at rest to mobilize and expand the distance between them, relaxing the bond and, therefore, also the joint structure. An example of this process is the heating of metals in steel factories to shape them and then let them return to solidity (when cooling).
- Sublimation. Transition from solid to gas (without passing through liquid). This usually requires specific pressure conditions, such as those reached by snow or ice on mountain peaks, where it will never reach a melting temperature, but passes directly to vapor. We can see this effect in dry ice (frozen CO2).
Changes in liquid state
The liquid state of aggregation can become solid or gaseous through processes known as:
- Solidification. The change from liquid to solid when pressure is applied to the liquid. As a result, kinetic energy (heat) is lost, causing the particles to begin to move much more slowly until they form a fixed (geometric in the case of crystallization) and constant structure. An example of this is the solidification of water.
- Freezing. Change from liquid to solid when a decrease in temperature below the freezing point of the liquid is applied.
- Vaporization. Passage from liquid to gaseous, generally due to the increase in the temperature of the liquid, which causes the separation of its already loose links between particles and, therefore, the loss of its cohesion. This is what happens when we boil water.
Changes in gaseous state
The gaseous state can become solid, liquid or plasma, according to the following processes:
- Condensation and liquefactionThese two processes involve the transition from a gaseous to a liquid state. Condensation occurs through the loss of kinetic energy (cooling), as occurs in clouds high in the atmosphere during the water cycle. Liquefaction occurs through an increase in pressure that forces the particles to come together and interact again.
- Reverse deposition or sublimation. This is the name given to the change from a gaseous state to a solid state, which can also be called crystallization. It occurs, for example, in frozen air, whose water vapor passes directly to ice crystals.
- IonizationIt occurs due to the loss of electrons from the atoms of a gas, due to an increase in the movement of its particles, which leads to the state of plasma aggregation.
Changes in plasma status
Matter in the plasma state can return to the gaseous state through a process called deionization, in which heat is removed and its particles recover the lost electronsbecoming a gas again.
Other states of aggregation
Currently, numerous different states of aggregation are being experimented with, which give rise to particular substances such as ferrofluidsairbrushes and a whole range of new materials.
References:
- General Chemistry. Eduardo J. Bottani, Hector S. Odetti, Oscar H. Pliego and Eduardo R. Villarreal. 2006. ISBN: 987-508-596-0
- Chemistry I. Introduction to the study of matter. Ana Beatriz Picado and Milton Alvarez. Editorial Universidad Estatal a Distancia. 2008. ISBN: 978-9965-31-626-2
- General Physics. 32nd edition. Santiago Burbano de Ercilla, Enrique Burbano García and Carlos Gracia Muñoz. Tebar Editorial. ISBN: 978-84-95447-82-1
- “State of Aggregation of Matter” in Wikipedia.